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MAY 2015

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PREVENTING HAMSTRING

STRAIN INJURY EDITIONBy Chris Beardsley

WelcomeWelcome to the Preventing Hamstring Strain InjuryEdition! In this edition, we report the findings of abrand new randomi ed controlled trial e ploring theeffects of the "ordic curl on the incidence of newhamstring strains# In other words, we review a veryhigh $uality study that attempted to find out whetherperforming the "ordic curl regularly would actuallystop hamstring strains from happening in the firstplace# Previous trials have shown that the "ordic curlwas very good at preventing recurrent hamstringstrains but the evidence for their use in avoiding newhamstring strains was wea%er# &his new trial shows us

that they are very valuable for both purposes# Indeed,despite the determined efforts of a small number of popular sports coaches who disli%e the e ercise, itseems that the evidence continues to grow to supportthe use of the "ordic curl to prevent hamstring strainsin a range of sports#

Preventing Hamstring Strain Injury Edition

IntroductionHamstring strains are very common in a range of different team sports# &he incidence of hamstringstrain injury has been e plored by researchers inrugby union and 'merican football and rangesbetween (#)* + #- injuries per .,((( e posure hours,depending upon the sport and on the e act definitionof e posure# /ore importantly, the proportion of totalinjuries comprised of hamstring strains in commonteam sports varies between .) + . 0 in 'ustralian1ules 2ootball, trac% and field, and soccer# Sincehamstring strains can be $uite debilitating and difficultto recover from, finding a way to stop them happeningin the first place would be very valuable#

MechanismsEccentric training has been proposed as a method of training for the hamstrings that may be useful forpreventing hamstring strains from occurring# &hereare at least two mechanisms that could e plain why

eccentric training might be effective for preventinghamstring strains# 2irstly, eccentric training seems toincrease the normali ed lengths of muscle fibers andthereby ma%es it easier for them to lengthen duringhigh3velocity, lengthening movements such as sprintrunning# Secondly, it has been suggested that sincelow eccentric hamstrings strength is a ris% factor forhamstring strains, athletes who incur these injuriesmight simply have a wea%ness in these %ey sprintingmuscles that leads to fatigue, overuse and ultimatelyinjury# 4iven that the hamstrings are much moredifficult to train with regularity than the $uadricepsusing common, multi3joint e ercises, this is not verysurprising#

Increasing normalized muscle lengths&he idea that it is possible to change the normali edlength of a muscle fiber using eccentric training is notwidely %nown or understood# &he normali ed musclelength of a muscle fiber is its resting length adjustedso that the length of each individual sarcomere isstandardi ed to )# 5m# Essentially, the normali ed

muscle length is a count of the number of sarcomeresin series# 6onger normali ed muscle lengths mean thatthere are more sarcomeres in series# Eccentric trainingincreases the number of sarcomeres in series in amuscle fiber, by a process called sarcomerogenesis#&he effects of this can be observed easily by testingstrength at different joint angles# Eccentric training of any muscle increases the optimum angle at whichtor$ue is developed# Producing pea% force at higheroptimum joint angles means that the muscles aredeveloping pea% forces at longer muscle lengths#Increasing the number of sarcomeres changes theamount of overlap between the sarcomeres such thatthe ma imum amount of overlap occurs at a longer

muscle length# Since the ma imum amount of overlapcorresponds with pea% force, increasing the number of sarcomeres means that muscles develop pea% force atlonger muscle lengths#

Preventing novel hamstring strains: the trialsWith the arrival of the new trial, there are now - trialse ploring the effects of eccentric training for thehamstrings on the incidence of novel hamstring straininjury, as follows7

Askling ( 2 ! " e plored the effects of .( wee%s of eccentric3emphasis training for %nee fle ion using aflywheel ergometer in 8) elite male soccer playersfrom ) Swedish premier3league teams# &hey found a

significant reduction in hamstring strain injury in theeccentric training group#

#a$$e ( 2 % " e plored the effects of .) wee%s of eccentric "ordic hamstring curl training for .) sets of - repetitions in * amateur 'ustralian 1ules 2ootballclubs and found no significant reduction in hamstringstrain injury in the eccentric training group but therelative ris% displayed a non3significant trend in thatdirection#

Enge$retsen ( 2 & " e plored the effects of .)wee%s of eccentric "ordic hamstring curl training for )+ 8 sets of + .( reps in .-. soccer players at high3ris% of hamstring strain injury and found no significant

reduction in hamstring strain injury in the eccentrictraining group#

Arnason ( 2 & " e plored the effects of at least *months of eccentric "ordic hamstring curl training for) + 8 sets of 9 + .) reps in elite soccer teams inIceland and "orway and found a significant benefit of the eccentric training#

Petersen ( 2 '' " e plored the effects of .( wee%s of eccentric "ordic hamstring curl training for ) + 8 setsof + .) repetitions, . + 8 times per wee% in malesoccer players in the top :anish soccer divisions andfound a significant benefit of the eccentric training#

;opyright Strength and ;onditioning 1esearch 6imited, )(.

http://www.ncbi.nlm.nih.gov/pubmed/12859607










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Preventing novel hamstring strains continued...Petersen ( 2 ' " e plored the effects of .8 wee%s of eccentric "ordic hamstring curl training . + ) timesper wee%, for ) + 8 sets of + .( repetitions inamateur male soccer players# &hey found a significantbenefit of the eccentric training#

Preventing novel hamstring strains: the reviews' previous review and meta3analysis by 4oode et al#<)(.=> included = of the above trials and reported thatwhile the trials involving eccentric hamstring trainingdid not significantly reduce the ris% of hamstringinjury, there was a non3significant trend <ris% ratio of (# ? times> and significant heterogeneity betweentrials# Importantly, the systematic review and meta3analysis performed by 4oode et al# <)(.=> found thatmost of this heterogeneity came from differences incompliance between trials# When considering onlythose subjects who were compliant with the eccentrictraining, there was actually an overall significantreduction in hamstring injury ris% <ris% ratio of (#8

times> and this effect had little heterogeneity# &he factthat compliance was the %ey factor that drovedifferences between study results implies that theeccentric training was having a very mar%ed effect onhamstring strain injury incidence#

Evidence for the Nordic hamstring curl In evidence3based practice, which values science andthe scientific process above opinion, the highest levelsof evidence are awarded to high $uality, long3termstudies that measure the e act outcome that we areloo%ing to achieve# When attempting to find evidencefor the prevention of hamstring strains, the aboveanalysis shows long3term, controlled trials that havemeasured actual numbers of hamstring strains withand without a training program of "ordic curls# &hesestudies show that when using the "ordic curl intraining, there are definitively fewer hamstring strains#&his body of literature is therefore the highest level of evidence that is possible to obtain for this area of sports science#

Criticizing the Nordic hamstring curl: training theory Several criticisms have been directed at the "ordichamstring curl# @ne type of criticism is based uponfundamental movement training theory# 2or e ample,it is often suggested that training muscles rather thanmovements, training %nee fle ion rather than hipe tension, or training the hamstrings outside of the

%inetic chain <in all cases by using a single3joint, %neefle ion e ercise li%e the "ordic curl> must necessarilybe less effective for both athletic performance and forinjury prevention than using a multi3joint e ercise#&hese suggestions are made because multi3jointe ercises are designated as more AfundamentalB thansingle3joint movements# However, the above trialsshow that while these training theories sound veryplausible, they are clearly false when it comes to thesubject of injury prevention, as the subjects in theabove trials engaged in multi3joint e ercise in bothgroups but the groups that also performed the "ordiccurl or other, similar e ercises displayed fewerinjuries#

;learly, athletes should engage in multi3joint e ercisesmost of the time, as these types of e ercise are morewell3suited to improving sports performance# However,the "ordic curl is not being proposed as an e ercisefor athlete development but for injury prevention#:eliberately omitting an e ercise on the basis that itdoes not fit a training theory for performance even

though it has been shown to be effective for injuryprevention using long3term trials that directly measureinjury incidence is not being fair to the athlete, as itris%s their future in the sport#

Criticizing the Nordic hamstring curl: biomechanics'nother type of criticism directed at the use of the"ordic curl involves discussions of the biomechanics of sprint running# &hese discussions draw attention tothe differences in biomechanics of the "ordic curl andthe biomechanics of sprint running, suggesting thatbecause the "ordic curl is performed slowly and usesdifferent joint angle movements to those used duringsprint running, it must be a useless e ercise fordeveloping sprinting speed# &his is based on the ideathat transfer to training can be deduced based uponsimilarities in the %inematics <joint angle movements>between an e ercise and a sports activity# Indeed, asnoted above, it is entirely possible that the "ordic curlmay not be a valuable e ercise for improving sprintingspeed# However, that is not the point# &he e ercise isbeing proposed as a tool for hamstring strain injuryprevention# 'nd based on the long3term trials, whichare the highest form of evidence, it seems to do its

job very well#

Conclusions&here is high $uality evidence for the use of eccentrichamstring training, particularly using the "ordic curl,for preventing hamstring strains# ;riticisms of thee ercise often appeal to inferior forms of evidence,such as training theory and biomechanics, which maynot even be relevant if they relate to performancerather than injury prevention#


http://injuryprevention.bmj.com/content/20/4/e8.short


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Strength coach notes

The effects of adding single !oint e"ercises to a multi !oint e"ercise resistance training

#rogram on u##er bodymuscle strength and size intrained men

&he researchers concluded that adding single3joint e ercises to a multi3jointresistance training program does not appear to increase further gains inmuscular strength and si e# &hey therefore suggest that for ma imal efficiencyof training, single3joint e ercises can be removed from training programs#

Effects of low versus highload resistance training onmuscle strength andhy#ertro#hy in well trainedmen

&he researchers concluded that both heavy and light relative loads increasemuscular si e similarly in trained subjects# However, they also concluded thatheavy loads are superior to light loads for increasing muscular strength#

Is re#etition failure critical forthe develo#ment of musclehy#ertro#hy and strength$

&he researchers concluded that training to muscular failure is not necessary toachieve gains in strength and si e#

%loc& versus wee&lyundulating #eriodizedresistance training #rogramsin women

&he researchers concluded that a non3linear, wee%ly undulating periodi ationmodel may be superior to a bloc% periodi ation model in a .(3wee% resistancetraining program for increasing ma imum lower body strength, si e and jumpingperformance in resistance3trained females#

Elastic bands in combinationwith free weights in strengthtraining: neuromusculareffects

&he researchers concluded that the variable and constant load e ternalresistance types led to similar increases in strength and athletic performance#

'hort term effect of crunche"ercise fre(uency onabdominal muscle endurance

&he researchers concluded there was no difference between the groups training., ), or 8 days per wee% in the increase in abdominal muscle endurance, asmeasured by the bench trun% curl test# &hey therefore suggested that a smallamount of crunch training <. day per wee%> might be sufficient for increasingabdominal muscle endurance in adolescents#

)cute effects of antagoniststatic stretching in the interset rest #eriod on re#etition

#erformance and muscleactivation

&he researchers found that passive stretching of the antagonist muscles duringthe seated row e ercise led to a significant increase in the number of repetitionsperformed as well as increased muscle activity of the latissimus dorsi and bicepsbrachii muscles#

*inematic and sEM+ analysisof the bac& s(uat at differentintensities with and without&nee wra#s

&he researchers concluded that increasing relative load with and without %neewraps during the s$uat e ercise leads to increased muscle activity in the vastuslateralis and gluteus ma imus# &hey noted that the use of %nee wraps with highrelative loads led to reduced muscle activation of the vastus lateralis but not inthe gluteus ma imus# &hey suggested that this reduction in muscle activity

might be caused by the storage of elastic energy in the %nee wraps that ma%esthe movement easier to perform#

,ower e"tremity strength andthe range of motion inrelation to s(uat de#th

&he researchers concluded that an%le dorsifle ion 1@/ with a fle ed %nee andhip fle ion are important factors for enabling deep s$uatting in males, whilean%le dorsifle ion with an e tended %nee and an%le dorsifle or strength areimportant factors for enabling deep s$uatting in in females# &his may indicatethat increasing an%le dorsifle ion 1@/, increasing hip fle ion 1@/, andincreasing an%le dorsifle or strength might lead to improved s$uat depth#


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S)orts medicine notes

The structural and mechanical #ro#erties of the )chilles tendon -years after surgical re#air

&he researchers concluded that the mechanical properties of previouslyruptured and surgically repaired tendons ) years post3repair are notaffected by the type of rehabilitation method that is conducted immediatelyafter surgery# &hey therefore suggest that early mobili ation treatment is as

appropriate as traditional rehabilitation#

uman tendon ada#tation inres#onse to mechanical loading: asystematic review and metaanalysis of e"ercise interventionstudies on healthy adults

&he researchers concluded that tendons respond to increased mechanicalloading by altering mechanical, material, and morphological properties#&hey also concluded that more effective training interventions involve highrelative loads <C*(0 of /DI;> over longer durations <C.) wee%s>#

Preventive interventions fortendino#athy: a systematic review

&he researchers concluded that there is limited evidence that a long3termintervention of soccer3specific balance training may be effective forpreventing patellar and 'chilles tendinopathy, while shoc% absorbing insolesmay also be effective for preventing 'chilles tendinopathy# &hey noted thatH1& seems to reduce the ris% of 'chilles tendinopathy in post3menopausal

women#

Immediate combined effect ofgastrocnemius stretching andsustained talocrural !ointmobilization in individuals withlimited an&le dorsifle"ion: arandomized controlled trial

&he researchers concluded a combined intervention comprising both staticstretching and talocrural joint mobili ation was more effective than staticstretching only for increasing an%le dorsifle ion and the time to heel3offduring wal%ing gait# &hey also noted that there was a non3significant trendfor greater passive dorsifle ion 1@/ following the combined treatment#

'hort term effectiveness of neuralsliders and neural tensioners as anad!unct to static stretching ofhamstrings on &nee e"tension

angle in healthy individuals: arandomized controlled trial

&he researchers found that all treatments led to significantly increasedpassive %nee e tension angle# &hey found that both combined treatmentswere significantly superior to the static stretching only intervention butthere were no significant differences between the two combined treatments#

Immediate effects ofneurodynamic sliding versusmuscle stretching on hamstringfle"ibility in sub!ects with shorthamstring syndrome

&he researchers concluded that neurodynamic sliding techni$ues appear tobe able to improve hamstring fle ibility at least as well as static stretching,if not to a greater e tent#

Effectiveness analysis of activestretching versus active stretching

#lus low fre(uency electricalstimulation in children who #laysoccer and who have the short

hamstring syndrome

&he researchers concluded that a long3term program of active stretchingplus &E"S was superior to a long3term program of active stretching only forincreasing hamstring fle ibility#

The im#act of neuromuscularelectrical stimulation on recoveryafter intensive/ muscle damaging/ma"imal s#eed training in

#rofessional team s#orts #layers

&he researchers concluded that "/ES can be used to improve )=3hourrecovery in soccer players, as measured by reference to countermovement

jump height ability, creatine %inase levels, and perceived soreness#


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Strength and C nd!" n!ng Re#ear$h

CONTENTS

HAMSTRINGS STRAIN INJURY EDITION%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

CONTENTS%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

1% STRENGTH & CONDITIONING' PO(ER AND HYPERTROPHY%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

1. The efects o adding single-joint exercises to a mul -joint exercise resistance training program on upper body muscle strength and sizein trained men, De ran!a, "ranco, #uedes $unior, #en l, %teele, and Teixeira, in &pplied 'hysiology, (utri on, and )etabolism *+ 1 /

+. 0fects o lo - 2ersus high-load resistance training on muscle strength and hypertrophy in ell-trained men, by %choen eld, 'eterson,3gborn, 4ontreras, and %onmez, in The $ournal o %trength 5 4ondi oning 6esearch *+ 1 ................ ..................................... ..............1

7. 8s repe on ailure cri cal or the de2elopment o muscle hypertrophy and strength9 "y %ampson, and #roeller, in %candina2ian $ournal o )edicine 5 %cience in %ports *+ 1 ........................................... ..................................... ...................................... ..................... 11

:. "loc; 2ersus ee;ly undula ng periodized resistance training programs in omen, by "artolomei, %tout, u;uda, <ofman, and )erni,in The $ournal o %trength 5 4ondi oning 6esearch *+ 1 ............................................... ...................................... ................................... 1+

. 0las c bands in combina on ith ree eights in strength training= neuromuscular efects, by &ndersen, imland, >olnes, and

%aeterba;;en, in The $ournal o %trength 5 4ondi oning 6esearch *+ 1 ...... ...................................... ..................................... ............... 17?. 0fects and mechanisms o tapering in maximizing muscular strength, by 'ritchard, >eogh, "arnes, and )c#uigan, in %trength 5

4ondi oning $ournal *+ 1 .........................................................................................................................................................................1:

@. %hort-term efect o crunch exercise reAuency on abdominal muscle endurance, by $uan-6ecio, BCpez- i2ancos, )oya, %arabia, andera-#arcia, in The $ournal 3 %ports )edicine &nd 'hysical itness *+ 1 ...................................... ..................................... ...................1

E. The efect o long term isometric training on coreFtorso s fness, by Bee and )c#ill, in The $ournal o %trength 5 4ondi oning 6esearch*+ 1 ....................................................... ..................................... ...................................... ...................................... ................................... 1?

/. &cute efects o antagonist sta c stretching in the inter-set rest period on repe on per ormance and muscle ac 2a on, by )iranda,)aia, 'az and 4osta, in 6esearch in %ports )edicine *+ 1 .................... ...................................... ..................................... ....................... 1@

1 . 8mpact o limited hamstring Gexibility on 2er cal jump, ;ic;ing speed, sprint, and agility in young ootball players, by #arcHa-'inillos,6uiz-&riza, )oreno Del 4as llo, and Batorre-6omIn, in $ournal o %ports %ciences *+ 1 ................ ...................................... .................. 1E

11. <al -sAuat or jump sAuat training under op mum po er load condi ons to counteract po er and speed decrements in "razilian elitesoccer players during the preseason, by Boturco, 'ereira, >obal, JaneK, #il, >itamura, and (a;amura, in $ournal o %ports %ciences

*+ 1 ....................................................... ..................................... ...................................... ...................................... ................................... 1/1+. Training or po er and speed= efects o increasing or decreasing jump-sAuat 2elocity in elite young soccer players, by Boturco,

(a;amura, >obal, #il, 4al, 4uniyochi, and 6oschel, in The $ournal o %trength 5 4ondi oning 6esearch *+ 1 ..................................... . +

17. %port-speciLc training targe ng the proximal segments and thro ing 2elocity in collegiate thro ing athletes, by 'almer, Mhl, <o ell,<e eN, iele, and )aNacola, in $ournal o &thle c Training *+ 1 ..........................................................................................................+1

1:. 'eripheral heart ac on *'<& training as a 2alid subs tute to high intensity inter2al training to impro2e res ng cardio2ascular changesand autonomic adapta on, by 'iras, 'ersiani, Damiani, 'erazzolo, and 6aO, in 0uropean $ournal o &pplied 'hysiology *+ 1 ....... ....++

2% *IOMECHANICS AND MOTOR CONTRO+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

1 . 4ontrol o propulsion and body liP during the Lrst t o stances o sprint running Q a simula on study, by Debaere, Delecluse, &erenhouts, <agman, and $on;ers, in $ournal o %ports %ciences *+ 1 ........ ..................................... ...................................... .................+:

1?. %elected determinants o accelera on in the 1 m sprint, by )aR;aSa, os a;, and >o als;i, in $ournal o <uman >ine cs *+ 1 . .... .+

1@. 'hysical principles demonstrate that the biceps emoris muscle rela 2e to the other hamstring muscles exerts the most orce Qimplica ons or hamstring muscle strain injuries, by Dolman, errall, and 6eid, in )uscles, Bigaments and Tendons $ournal *+ 1 .. .. .+?

1E. >inema c and s0)# analysis o the bac; sAuat at diferent intensi es ith and ithout ;nee raps, by #omes, "ro n, %oares, Da%il2a, De 3li2eira %il2a, %erpa, and )archeK, in The $ournal o %trength 5 4ondi oning 6esearch *+ 1 ...................................... .........+@

1/. Bo er extremity strength and the range o mo on in rela on to sAuat depth, by >im, > on, 'ar;, $eon, and eon, in $ournal o <uman>ine cs *+ 1 ..............................................................................................................................................................................................+E

+ . 0fects o an unstable load on orce and muscle ac 2a on during a parallel bac; sAuat, by Ba rence and 4arlson, in The $ournal o%trength 5 4ondi oning 6esearch *+ 1 ....................................................................................................................................................+/

+1. 0fects o isometric Auadriceps strength training at diferent muscle lengths on dynamic torAue produc on by (oor;Ui2, (osa;a, and"laze2ich, in $ournal o %ports %ciences *+ 1 ............................................................................................................................................7

++. 8nhomogeneous Auadriceps emoris hypertrophy in response to strength and po er training, by 0arp, (e ton, 4ormie, and "laze2ich,in )edicine 5 %cience in %ports 5 0xercise *+ 1 .......................................................................................................................................71


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+7. 8nGuence o bench angle on upper extremity muscular ac 2a on during bench press exercise, by Bau2er, 4ayot, and %cheuermann, in0uropean $ournal o %port %cience *+ 1 ........................ ...................................... ..................................... ...................................... .......... 7+

+:. Training-related changes in the 0)#-moment rela onship during isometric contrac ons= urther e2idence o impro2ed control omuscle ac 2a on in strength-trained men9 "y &maran ni and "ru, in $ournal o 0lectromyography and >inesiology *+ 1 .................77

+ . Dissociated me course o muscle damage reco2ery bet een single and mul -joint exercises in highly resistance trained men, by%oares, erreira-$unior, 'ereira, 4leto, 4astanheira, 4adore, and "oNaro, in The $ournal o %trength 5 4ondi oning 6esearch *+ 1 ...7:

+?. )uscle ascicle beha2ior during eccentric cycling and its rela on to muscle soreness, by 'eVailillo, "laze2ich and (osa;a, in )edicine 5%cience in %ports 5 0xercise *+ 1 ..............................................................................................................................................................7

+@. erbal instruc ons acutely afect drop 2er cal jump biomechanics Q implica ons or athle c per ormance and injury ris; assessments,by >huu, )usalem, and "each, in The $ournal o %trength 5 4ondi oning 6esearch *+ 1 . ...................................... .............................. 7?

+E. Diferences in end range o mo on 2er cal jump ;ine c and ;inema c strategies bet een trained eightliPers and elite short trac;speed s;aters, by <aug, %praWord, illiams, 4hapman, Drin; ater, <aug, Be2errier %treet, in The $ournal o %trength 5 4ondi oning6esearch *+ 1 ............................................................................................................................................................................................7@

,% ANATOMY' PHYSIO+OGY' AND NUTRITION%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

+/. 0xtracellular matrix remodeling and its contribu on to protec 2e adapta on ollo ing lengthening contrac ons in human muscle, by<yldahl, (elson, elling, #roscost, <ubal, and 'arcell, in The &%0" $ournal *+ 1 . ...................................... ..................................... .... 7/

7 . 8s it me to turn our aNen on to ard central mechanisms or post-exer onal reco2ery strategies and per ormance9 "y 6aNray, &rgus,)ar n, (orthey, and Driller, in ron ers in 'hysiology *+ 1 ................................... ..................................... ...................................... ......:

71. Does regular post-exercise cold applica on aNenuate trained muscle adapta on9 "y Xamane, 3hnishi, and )atsumoto, in8nterna onal $ournal o %ports )edicine *+ 1 ...................... ...................................... ..................................... ...................................... .. :1

7+. )ental a gue does not afect maximal anaerobic exercise per ormance, by )ar n, Thompson, >eegan, "all, and 6aNray, in 0uropean $ournal o &pplied 'hysiology *+ 1: ...................................................... ..................................... ...................................... .......................... :+

77. <igh-protein, lo - at, short-term diet results in less stress and a gue than moderate-protein, moderate- at diet during eight loss inmale eightliPers= a pilot study, by <elms, Jinn, 6o lands, (aidoo, and 4ronin, in 8nterna onal $ournal o %port nutri on and 0xercise)etabolism *+ 1: .......................................................................................................................................................................................:7

7:. 8ndependent efects o endurance training and eight loss on pea; at oxida on in moderately o2er eight men= a randomizedcontrolled trial, by (ordby, 6osen;ilde, 'loug, esth, eigh, (ielsen, and %tall;necht, in $ournal o &pplied 'hysiology *+ 1 ..............::

7 . The impact o neuromuscular electrical s mula on on reco2ery aPer intensi2e, muscle damaging, maximal speed training in pro essional team sports players, by Taylor, est, <o atson, $ones, "rac;en, Bo2e, and >ilduf, in $ournal o %cience and )edicine in%port *+ 1: ..................................................................................................................................................................................................:

7?. The impact o high-intensity inter2al training 2ersus moderate-intensity con nuous training on 2ascular unc on= a systema c re2ieand meta-analysis, by 6amos, Dallec;, Tjonna, "eetham, and 4oombes in %ports )edicine *+ 1 ..................................... .................... :?

-% PHYSICA+ THERAPY AND REHA*I+ITATION%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

7@. The pre2en 2e efect o the (ordic hamstring exercise on hamstring injuries in amateur soccer players Q a randomized controlled trial,an der <orst, %mits, 'etersen, #oedhart, and "ac;x, in 8njury 're2en on *+ 1: ........... ...................................... ................................... :E

7E. 0ccentric hamstring strength and hamstring injury ris; in &ustralian ootballers, by 3par, illiams, Timmins, <ic;ey, Duhig, and %hield,in )edicine 5 %cience in %ports 5 0xercise *+ 1: .......................................................................................................................................:/

7/. 8mmediate combined efect o gastrocnemius stretching and sustained talocrural joint mobiliza on in indi2iduals ith limited an;ledorsiGexion= a randomized controlled trial, by >ang, 3h, > on, eon, &n, and Xoo, in )anual Therapy *+ 1 ................................ ......

: . 8mmediate efects o neurodynamic sliding 2ersus muscle stretching on hamstring Gexibility in subjects ith short hamstring syndrome,by 4astellote-4aballero, alenza, 'uentedura, ernIndez-de-las-'eVas, and &lburAuerAue-%endHn, in $ournal o %ports )edicine *+ 1:...................................................................................................................................................................................................................... 1

:1. %hort term efec 2eness o neural sliders and neural tensioners as an adjunct to sta c stretching o hamstrings on ;nee extension anglein healthy indi2iduals= a randomized controlled trial, by %harma, "althillaya, 6ao, and )ani, in 'hysical Therapy in %port *+ 1 .... .... . +

:+. 0fec 2eness analysis o ac 2e stretching 2ersus ac 2e stretching plus lo - reAuency electrical s mula on in children ho play soccerand ho ha2e the short hamstring syndrome, by 'iAueras-6odrHguez, 'alazCn-"ru, and #il-#uillYn, in 4linical $ournal o %port )edicine*+ 1 ....................................................... ..................................... ...................................... ...................................... ................................... 7

:7. The structural and mechanical proper es o the &chilles tendon + years aPer surgical repair, by #eremia, "obbert, (o2a, 3N, De &guiar Bemos, De 3li2eira Bupion, and az, in 4linical "iomechanics *+ 1 ........................ ...................................... ...................................... ..... :

::. 're2en 2e inter2en ons or tendinopathy= a systema c re2ie , by 'eters, J er2er, Dierc;s, 0l erin;-#emser, an den &;;er-%chee;, in $ournal o %cience and )edicine in %port *+ 1 ................. ...................................... ..................................... ...................................... .......

: . oot posture and unc on ha2e only minor efects on ;nee unc on during bare oot al;ing in healthy indi2iduals, by "uldt, Be2inger,)urley, )enz, (ester, and Bandor , in 4linical "iomechanics *+ 1 ................ ...................................... ..................................... ............... ?

:?. %ix ee;s o core stability training impro2es landing ;ine cs among emale capoeira athletes= a pilot study, by &raujo, 4ohen, and<ayes, in $ournal o <uman >ine cs *+ 1 ................................................................................................................................................. @


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:@. 4ore strength training or pa ents ith chronic lo bac; pain, by 4hang, Bin, and Bai, in $ournal o 'hysical Therapy %cience *+ 1 . . . E

:E. 0xercise-based per ormance enhancement and injury pre2en on or LreLghters= contras ng the Ltness- and mo2ement-relatedadapta ons to t o training methodologies, by rost, "each, 4allaghan, and )c#ill, in The $ournal o %trength 5 4ondi oning 6esearch*+ 1 ....................................................... ..................................... ...................................... ...................................... ................................... /

:/. "alancing Zhands-on[ ith Zhands-of[ physical therapy inter2en ons or the treatment o central sensi za on pain in osteoarthri s,by #irbYs, )eeus, "aert, and (ijs, in )anual Therapy *+ 1: .................................. ..................................... ...................................... ....... ?

. Boss o range o mo on o the hip joint= a hypothesis or e ology o sports hernia, by 6ambani and <ac;ney, in )uscles, Bigaments and Tendons $ournal *+ 1 ............................................ ..................................... ...................................... ..................................... .................... ?1


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1% STRENGTH & CONDITIONING' PO(ER AND

HYPERTROPHY


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The effects of adding single !oint e"ercises to a multi !oint e"ercise resistance training #rogram on u##er body muscle strength and size in trained men/ 0e1ran2a/ %ranco/ +uedes 3unior/ +entil/ 'teele/ and Tei"eira/ in )##lied Physiology/ Nutrition/ and Metabolism 4 -567 8

BackgroundDery little long3term research has e plored the effectsof altering e ercise selection on gains in muscularstrength, si e or power# E ercise selection can beviewed in several different ways# @ne approach is tocompare the effects of two or more specific e ercises,such as the s$uat or deadlift# However, this is rarelydone, as it provides conclusions that are limited solelyto a single decision between those e ercises and thefindings cannot easily be e trapolated out to othersituations# &herefore, an alternative approach that ismore common is to categori e e ercises into broadtypes and compare the effects of long3term trainingprograms within those types# @ne e ample of thiscategori ation is the division of training programs intogroups performing a small number of e ercises <lowe ercise variety> and those performing a large numberof e ercises <high e ercise variety># &his is aninteresting area of research, as it reflects a commoncoaching debate most easily represented by the

ulgarian approach to weightlifting on the one hand<high speciali ation in a few e ercises> and the1ussian approach on the other <large variety of speciale ercises># Powerlifting programs often polari e in thesame way, with some programs <such as Westside>ma%ing use of many e ercises and others focusingpurely on the main lifts# &o date, very little researchhas been carried out in this area but the limitedevidence indicates that at least three multi3jointe ercises for the lower body might be superior to onemulti3joint e ercise# 'nother e ample of suchcategori ation might be the division of resistancetraining e ercises into either single3joint movementsand multi3joint movements# Previous wor% in this areahas been very limited but has typically reported nodifferences between groups training with either single3

join t or mult i3jo int resistance training e ercisestargeting the same body parts# &hus, researcherswor%ing in this field have concluded that whereefficiency is a priority, then multi3joint e ercisesshould be preferred, as this enables individuals totrain multiple muscle groups at the same time#

*B+EC,I-E. &o compare the increases in muscularstrength <as measured by elbow fle ion .1/> and si e<as measured by fle ed and un3fle ed measures of arm circumference> between resistance trainingprograms involving upper body multi3joint e ercisesand those involving both upper body multi3joint andupper body single3joint e ercises, in trained subjects#

P*P/0A,I*1. )( young, resistance3trained males,randomly allocated into either a combined multi3joint3plus3single3joint group <.( subjects, aged )*#* F -#-years> or a multi3joint only group <.( subjects, aged)?#= F =#- years>#

I1,E -E1,I*1. oth groups performed an 93wee%period of resistance training for the upper body,following a linear periodi ed program# oth groupsperformed both free weights and machine e ercisesfor the upper body, including various pressing andpulling movements# In addition, the combined groupalso performed triceps e tensions and biceps curls#Dolume was therefore greater in the combined group#

What ha))ened3

Muscular strength&he researchers reported that both training groupssignificantly increased elbow fle ion .1/ <multi3joint3only G #(0 combined G -#=0> but there was nosignificant difference between groups# &hey alsoreported that both training groups significantlyincreased elbow e tension .1/ <multi3joint3only G.(#-0 combined G ?#90> but there was again nosignificant difference between groups#

Muscular size&he researchers reported that both training groups

significantly increased fle ed arm circumference<multi3joint3only G .#90 combined G .# 0> and un3fle ed arm circumference <multi3joint3only G .#80combined G 8#)0> but there were no significantdifferences between groups#

What did the researchers conclude3&he researchers concluded that adding single3jointe ercises to a multi3joint resistance training programdoes not appear to increase further gains in muscularstrength and si e# &hey therefore suggest that forma imal efficiency of training, single3joint e ercisescan be removed from training programs#

0imitations&he study was limited in that the measurement of muscular si e was arm circumference# &his is not anoptimal measurement of hypertrophy and it is possiblethat the different e ercises produced gains inmuscular si e at different points along the biceps andtriceps muscles# 'lso, the muscles e amined were notas large as those in the lower body# :ifferent resultsmight be observed if the same study were performedwith multi3joint and single3joint e ercises for the lowerbody <e#g# s$uats plus %nee e tensions and glutebridges vs# s$uats only>#


http://www.nrcresearchpress.com/doi/abs/10.1139/apnm-2015-0109

http://www.nrcresearchpress.com/doi/abs/10.1139/apnm-2015-0109

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Effects of low versus high load resistance training onmuscle strength and hy#ertro#hy in well trained men/by 'choenfeld/ Peterson/ 9gborn/ Contreras/ and 'onmez/ in The 3ournal of 'trength Conditioning;esearch 4 -567 8

BackgroundEffect of relative load on strength gains;urrently, the evidence indicates that heavy loads aresuperior to light loads for increasing strength inuntrained individuals, where light loads are defined as

(0 of .1/# &his is on the basis of appro imately)= long3term trials comparing C) training groups, of which . reported a benefit in favor of heavy loads forat least one of the outcome measures for strengthwhile the remainder reported no differences betweengroups# &he evidence indicates that heavy loads mightalso be superior to moderate loads <where moderateloads are defined as . 1/> for increasing strength inuntrained individuals# However, this is on the basis of

around .. long3term trials comparing C) traininggroups, of which reported a benefit in favor of heavyloads for at least one of the outcome measures forstrength while the remainder reported no differencesbetween groups# ;urrently, the evidence for trainedindividuals is very limited# "o studies have yetcompared the effects of heavy and light loads onstrength gains but there are preliminary signs thatheavy loads might be superior to moderate loads forincreasing strength in that population for somee ercises or body parts at least#

/ore detail

Effect of relative load on size gains

;urrently, the evidence indicates that heavy loadsmight be superior but could also be $uite similar tolight loads for increasing muscular si e in untrainedindividuals, where light loads are defined as (0 of .1/# &his is on the basis of appro imately .8 long3term trials comparing C) training groups, of whichonly = reported a benefit in favor of heavy loads for atleast one of the outcome measures for muscular si ewhile all of the remainder reported no differencesbetween groups# &o date, there have been no studiespublished assessing the effects of heavy and lightloads in trained individuals#

/ore detail

*B+EC,I-E. &o compare the increases in muscularstrength <as measured by .1/ bac% s$uat and benchpress> and si e <as measured by ultrasound of theelbow fle ors, elbow e tensors and $uadriceps>between resistance training programs involving low<C. 1/> and high < . 1/> relative loads in trainedsubjects#

P*P/0A,I*1. .9 young, resistance3trained maleswere first matched for baseline strength levels andthen randomly assigned to either a low3load or a high3load group#

I1,E -E1,I*1. oth groups performed an 93wee%resistance3training program for the upper and lowerbody using the same 8 sets of * e ercises, 8 times perwee%# &he e ercises comprised7 the barbell benchpress, barbell military press, wide grip lat pull3down,seated cable row, barbell bac% s$uat, machine legpress, and machine %nee e tension# &he low3loadgroup performed ) + 8 repetitions per set pere ercise and the high3load group performed 9 + .)

repetitions per set#

What ha))ened3

Muscular strength&he researchers reported that the high3load groupsignificantly improved .1/ bench press <F-# 0> butthe improvement in the low3load group was notsignificant <F)#(0># However, the difference betweengroups did not reach statistical significance# &heresearchers reported that both the high3 and low3loadgroups significantly improved .1/ s$uat press<F.?#-0 and F9#90> and on this occasion the high3load group increased significantly more than the low3load group#

Muscular size&he researchers reported that both the high3 and low3load groups significantly improved elbow fle or musclethic%ness < #8 and 9#-0>, elbow e tensor musclethic%ness <-#(0 and #)0>, and $uadriceps musclethic%ness <?#80 and ?# 0> and there were nosignificant differences between groups#

What did the researchers conclude3&he researchers concluded that both heavy and lightrelative loads increase muscular si e similarly intrained subjects# However, they also concluded thatheavy loads are superior to light loads for increasing

muscular strength#

0imitations&he study was limited in that neither the volume northe volume load were e$uated between groups# &helow3load group performed appro imately 8 times thevolume of the high3load group# It is therefore unclearto what e tent the greater volume performed by thelow3load group influenced the results# It is alsounclear to what e tent the subjects felt that they hadrecovered from each wor%out in each program andwhether one program was easier to perform andrecover from than the other#


http://pdfs.journals.lww.com/nsca-jscr/9000/00000/Effects_of_Low__Versus_High_Load_Resistance.96938.pdf

http://www.strengthandconditioningresearch.com/strength/#2

http://www.strengthandconditioningresearch.com/hypertrophy/#2

http://pdfs.journals.lww.com/nsca-jscr/9000/00000/Effects_of_Low__Versus_High_Load_Resistance.96938.pdf



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Is re#etition failure critical for the develo#ment of muscle hy#ertro#hy and strength$ %y 'am#son/ and +roeller/ in 'candinavian 3ournal of Medicine 'cience in '#orts 4 -567 8

Background

Effect of muscular failure on strength gains;urrently, the evidence indicates that training at acloser pro imity to muscular failure is superior totraining further away from muscular failure forincreasing strength in untrained individuals# &his is onthe basis of = long3term trials comparing C) traininggroups, of which 8 reported a benefit in favor of training at a closer pro imity to muscular failure for atleast one of the outcome measures for strength whilethe other trial reported no differences betweengroups# &he evidence also indicates that training at acloser pro imity to muscular failure is superior totraining further away from muscular failure forincreasing strength in trained individuals# &his is on

the basis of long3term trials comparing C) traininggroups, of which 8 reported a benefit in favor of training at a closer pro imity to muscular failure for atleast one of the outcome measures for strength whilethe other ) trials reported no differences betweengroups#

/ore detail

Effect of muscular failure on size gains;urrently, the evidence indicates that training at acloser pro imity to muscular failure is superior totraining further away from muscular failure forincreasing muscular si e in untrained individuals# &hisis on the basis of ) long3term trials comparing C)

training groups, of which both reported a benefit infavor of training at a closer pro imity to muscularfailure for at least one of the outcome measures forstrength while the other trial reported no differencesbetween groups# &he evidence also indicates thattraining at a closer pro imity to muscular failure issuperior to training further away from muscular failurefor increasing strength in trained individuals# However,this is on the basis of only . long3term trial comparingC) training groups, which reported a benefit in favorof training at a closer pro imity to muscular failure forat least one of the outcome measures for strength#

/ore detail

*B+EC,I-E. &o compare the increases in muscularstrength <as measured by .1/ elbow fle ion andma imum voluntary isometric contraction </DI;>elbow fle ion tor$ue>, si e <as measured by magneticresonance imaging </1I> of the elbow fle ors>, andneural activation <as measured by electromyographyJE/4K> between three resistance training programs in

which the participants always trained to muscularfailure or predominantly not to muscular failure#

P*P/0A,I*1. )9 previously untrained males, whofirst undertoo% a =3wee% period of standardi edresistance training to muscular failure before beingdesignated as either high or low responders and thenrandomly allocated into one of 8 different groups#

I1,E -E1,I*1. 'll groups performed a .)3wee%resistance training program comprising = sets with9 0 of .1/ for the elbow fle ors, training 8 times perwee%# &he 8 groups trained using slightly differentnumbers of repetitions and pro imity to muscularfailure# &he failure group performed all sets to

muscular failure <typically - repetitions in each set>and trained using a )3second concentric and a )3second eccentric muscle action# &he fast3concentric3not3to3failure group trained without going to muscularfailure <= repetitions per set> and trained using ama imal concentric and a )3second eccentric muscleaction# 2inally, the fast3not3to3failure group trainedwithout going to muscular failure <= repetitions perset> and trained using a ma imal concentric and ama imal eccentric muscle action# oth not3to3failuregroups performed . set per wee% to failure in order toascertain the loading for the subse$uent wee%#

What ha))ened3

&he researchers reported that although all 8 groupsincreased muscular strength in both elbow fle ion .1/<pooled increase G 8.0> and /DI; elbow fle iontor$ue <pooled increase G .80>, there were nosignificant differences between groups# Similarly, theyreported that although all 8 groups increased musclesi e in the elbow fle ors <pooled increase G ..0>,there were no significant differences between groups#&he researchers also reported a significant increase inthe agonist E/4 activity during .1/ performance<pooled increase G ))0>, although there were againno significant differences between groups# ;are shouldbe ta%en in the interpretation of this result, as it doesnot reflect an increase in voluntary activation, which

would re$uire a measurement relative to involuntarystimulation#

What did the researchers conclude3&he researchers concluded that training to muscularfailure is not necessary to achieve gains in strengthand si e#

0imitationsoth not3to3failure groups performed . set per wee%

to failure each wee%# &his may have confounded theresults# 'lso, the failure group performed a greatervolume of training than the other groups#


http://onlinelibrary.wiley.com/doi/10.1111/sms.12445/full



http://onlinelibrary.wiley.com/doi/10.1111/sms.12445/full



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%loc& versus wee&ly undulating #eriodized resistancetraining #rograms in women/ by %artolomei/ 'tout/1u&uda/ offman/ and Merni/ in The 3ournal of 'trength Conditioning ;esearch 4 -567 8

Background

Effect of #eriodization on strength gains;urrently, the evidence indicates that training using aform of periodi ation is superior to training with noperiodi ation for increasing strength in untrainedindividuals# &his is on the basis of * long3term trialscomparing C) training groups, of which = reported abenefit in favor of training using a periodi ationmethod for at least one of the outcome measures forstrength, while the other trials reported no differencesbetween groups# &he evidence also indicates thattraining using a form of periodi ation is superior totraining with no periodi ation for increasing strengthin trained individuals# &his is also on the basis of *long3term trials comparing C) training groups, of

which 8 reported a benefit in favor of training at acloser pro imity to muscular failure for at least one of the outcome measures for strength while the othertrials reported no differences between groups# 2oruntrained subjects, the e act type of periodi ation foroptimi ing strength gains is unclear# "ot allperiodi ation methods have been compared# &o date,9 trials have compared non3linear and linearperiodi ation models in untrained subjects and while =have reported superior effects of non3linear, .reported a superior effect of linear, and the remainderfound no differences between groups# 2or trainedsubjects, periodi ation type for strength gains seemsto be irrelevant although not all periodi ation methods

have been compared in multiple trials# &o date, * trialshave compared non3linear and linear periodi ationmodels in trained subjects and all but . trial found nodifferences between groups#

/ore detail

Effect of #eriodization on size gains;urrently, the evidence indicates that training using aform of periodi ation might be superior to trainingwith no periodi ation for increasing muscular si e inuntrained individuals# However, this is only on thebasis of ) long3term trials comparing C) traininggroups, of which . reported a benefit in favor of training using a periodi ation method for at least oneof the outcome measures for strength, while the othertrial reported no differences between groups# @n theother hand, the evidence indicates that training usinga form of periodi ation is similar to to training with noperiodi ation for increasing muscular si e in trainedindividuals# However, is also on the basis of only )long3term trials comparing C) training groups, whichboth reported no differences between groups#

/ore detail

*B+EC,I-E. &o compare the changes in muscularstrength <as measured by .1/ s$uat, deadlift andbench press, and ma imal isometric mid3thigh pullforce>, body composition <using s%in3fold calipers>,and countermovement jump height following differentresistance training programs involving either bloc%periodi ation or non3linear <wee%ly undulating> in

resistance3trained females#

P*P /0A, I*1 . .* resistance3trained females,randomly allocated to either a bloc% periodi ationgroup <? subjects, aged )=#* L =#) years> or a non3linear periodi ation group <9 subjects, aged )8#) L)#) years>#

I1,E -E1,I*1. oth groups performed a .(3wee%resistance3training program, training 8 times per wee%with a similar volume and with the same e ercises#&he bloc% periodi ation group was subdivided into two

3wee% sections, comprising a hypertrophy section<high volume, low relative load> and a strength section<low volume, high relative load># &he non3linear

program varied these parameters from one wee% tothe ne t, training using a different scheme each wee%,in two similar 3wee% sections#

What ha))ened3

Muscular strength&he researchers found that countermovement jumpheight, .1/ s$uat, and .1/ deadlift all significantlyincreased in both groups, while .1/ bench press andmid3thigh pull isometric force did not# &hey noted that.1/ s$uat increased significantly more in the non3linear group than in the bloc% group <)*#*0 vs#. #)0>#

Muscular size&he researchers found that estimated lean body mass,arm muscle cross3sectional area, and thigh musclecross3sectional area increased significantly in bothgroups# &hey noted that thigh muscle cross3sectionalarea increased significantly more in the non3lineargroup than in the bloc% group < #90 vs# .#-0>#

What did the researchers conclude3&he researchers concluded that a non3linear, wee%lyundulating periodi ation model may be superior to abloc% periodi ation model in a .(3wee% resistancetraining program for increasing ma imum lower bodystrength, si e and jumping performance in resistance3

trained females#

0imitations&he study was limited as it only compared bloc% andwee%ly non3linear periodi ation models for a relativelyshort period of time# It is unclear whether othermodels might be superior# /oreover, it is unclearwhether these differences would be maintained after alonger duration#


http://pdfs.journals.lww.com/nsca-jscr/9000/00000/BLOCK_VERSUS_WEEKLY_UNDULATING_PERIODIZED.96954.pdf



http://pdfs.journals.lww.com/nsca-jscr/9000/00000/BLOCK_VERSUS_WEEKLY_UNDULATING_PERIODIZED.96954.pdf



8/18/2019 SCR_MAY_15_PDF


Elastic bands in combination with free weights instrength training: neuromuscular effects/ by

)ndersen/ 1imland/ *olnes/ and 'aeterba&&en/ in The 3ournal of 'trength Conditioning ;esearch 4 -567 8

Background

Elastic resistance3training using elastic resistancebands <E1 s> is commonly3used in rehabilitation#E1 s resist being lengthened and e ert a tensile forcedirected towards returning to their resting length#&ensile force at any length depends upon the elasticproperties# Elastic properties are described by astress3strain relationship, where stress is the tensileforce per unit area and strain is the ratio of totalincrease in length to starting length# &he stress3strainrelationship provides a measure of the amount of tensile force re$uired to increase the length of theband by a given distance# &he slope of the stress3strain relationship is the elastic modulus# Stress isplotted on the y3a is and strain on the 3a is, so alarger elastic modulus implies a steeper gradientwherein larger tensile forces are re$uired for the sameincreases in E1 length# &hus, stiffer E1 s have ahigher elastic modulus while less3stiff E1 s have alower elastic modulus# So using a stiffer E1 ma%es ane ercise harder# 'lso, the resistance that an E1provides at any given length increases with increasinglength# So an e ercise is harder with a pre3stretchedE1 than with an initially3slac% E1 # While E1 s areine pensive, versatile, lightweight, and unthreatening,they have disadvantages# 2irstly, when using E1 s, ane ercise will differ from a comparable e ercise usingfree weights as E1 s are a form of variable resistance#&he joint moments during elastic resistance trainingare a function of the length of the E1 , which is itself a function of joint angle in single3joint e ercises andof joint angles in multi3joint e ercises# Whethervariable resistance is more or less effective thanisoinertial resistance training for increasing strength,si e and power is unclear# Secondly, when stretchingan E1 , most e ercises involve ta%ing the E1 from ashortened state while the prime mover muscles arelengthened to a lengthened state while the primemover muscles are shortened# &hus, since the tensileforce e erted by the E1 increases with increasinglength, the difficulty of the e ercise is greatest whenthe E1 is longest and the prime mover muscles areshortened <i#e# contracted># &his is in contrast to free3weights e ercises, which tend to be most difficult

when the prime mover muscles are most lengthened#&hus, given that regional hypertrophy is %nown tooccur in response to e ercises where the muscles arestimulated most at different muscle lengths, E1 scould develop muscles in a different way from thesame e ercise performed with free3weights# &hirdly,E1 s differ from free weights in that it is not easy tomeasure how much force is being e erted in order toperform an e ercise# 2ree weight e ercises can be$uantified by reference to the load <in either poundsor %ilograms> but although E1 s are graded by color,it is not easy to %now how to progress the loading orto compare the E1 e ercise with a dumbbell e ercise#

*B+EC,I-E. &o compare the effects of variable <usingE1 s> and constant load e ternal resistance types onchanges in muscular strength <as measured by -1/bac% s$uat and %nee e tension ma imal voluntaryisometric contraction </DI;> force at -(, ?( and .)(degrees>, athletic performance <as measured bycountermovement jump height from the same 8 joint

angles> and neural activation, <as measured byelectromyography JE/4K during the /DI;s> after along3term resistance training program#

P*P/0A,I*1. 8) resistance3trained females <aged)( + == years>, randomly allocated either to a variableresistance or a constant load group#

I1,E -E1,I*1. oth groups performed a .(3wee%period of resistance training, involving the bac% s$uatand split s$uat, training ) days per wee%# &heconstant load group used standard barbell e ercisesand the variable resistance group used the samebarbell e ercises with the load split between freeweights and E1 resistance# &he contribution to the

total resistance from the bands in the top position was90 at the start of the program and 890 at the end

of the program, as load was added solely using freeweights, as the subjects increased in strength#

What ha))ened3

Muscular strength&he researchers reported that %nee e tension /DI;increased significantly in both groups at all 8 angles<-(, ?( and .)( degrees> but there was no significantdifference in respect of the increase between the )groups or between the 8 angles# Similarly, theyreported that -1/ bac% s$uat significantly increased inboth groups but there was no difference between the) groups#

Muscle activation&he researchers reported that muscle activity did notchange significantly as a result of the intervention ineither of the groups when measured during the /DI;or during the -1/ bac% s$uat#

Countermovement !um# height &he researchers reported that countermovement jumpheight increased significantly in both groups at all 8angles <-(, ?( and .)( degrees> but there was nosignificant difference in respect of the increasebetween the ) groups or between the 8 angles#

What did the researchers conclude3&he researchers concluded that the variable andconstant load e ternal resistance types led to similarincreases in strength and athletic performance#

0imitations&he study was limited in that the researchers did notmeasure change in muscle si e# &his was unfortunate,as few, if any, studies have measured differences inhypertrophy between programs involving e ercisesusing different types of e ternal load#


http://pdfs.journals.lww.com/nsca-jscr/9000/00000/ELASTIC_BANDS_IN_COMBINATION_WITH_FREE_WEIGHTS_IN.96955.pdf

http://pdfs.journals.lww.com/nsca-jscr/9000/00000/ELASTIC_BANDS_IN_COMBINATION_WITH_FREE_WEIGHTS_IN.96955.pdf

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Effects and mechanisms of ta#ering in ma"imizingmuscular strength/ by Pritchard/ *eogh/ %arnes/ and Mc+uigan/ in 'trength Conditioning 3ournal 4 -567 8

*B+EC,I-E. &o review the literature in order todiscuss the effects of tapering on ma imal strength#

,he evie4

Introduction&apering is a reduction in normal training load in orderto enhance performance at a competition or test# Itcan be performed for any sporting performance and iscommonly used in many popular team sports as wellas in trac% and field and in the main strength sports<@lympic weightlifting, strongman, and powerlifting>#

Ty#es of ta#er &he reviewers e plain that there are at least =different models of taper7 the step taper, the lineartaper, the slow e ponential decay taper, and the fast

decay e ponential taper# &he step taper involves asingle, one3off reduction in training volume at aparticular date prior to the competition# &he lineartaper involves a progressive reduction in volume froma certain date through to the competition# 2inally, thee ponential <fast and slow variations> taper involves anon3linear reduction in volume that is faster at thebeginning than towards the end of the tapering period#Mnfortunately, as the reviewers note, these = differenttapering styles have not been compared for theperformance of ma imal strength tests#

Effects of ta#ering on ma"imal strength&he reviewers assessed the limited literature anddeduced that tapering of any %ind appears to beeffective for improving ma imal strength over a shortperiod of time but the e act type of taper that isoptimal remains unclear# &hey note that there is atrend for superior results to be observed during taperswhere high relative loads are maintained while volumeis reduced in comparison with tapers in which relativeload is also reduced# &hey note that tapers that havebeen studied involved volume reductions of between8( + *(0 but whether this reduction is optimal is asyet un%nown#

Possible mechanisms of ta#ering&he reviewers noted that the literature regardingtapering is very limited# However, some indications

have emerged that provide clues regarding whatmechanisms underlie the beneficial effects thattapering has on ma imal strength# &he reviewers notestudies in which tapers were reported and whichfollowed prior phases of heavy training loads# &heynoted that elevated mar%ers of overreaching wereseen in these heavy training load phases, includingincreased cortisol3to3testosterone ratios, creatine%inase levels, glutamate levels, and glutamate3to3glutamine ratios# Such mar%ers were then reducedduring the subse$uent tapers# In addition, thereviewers note studies in which tapers were performedin which the researchers measured changes in neuralactivation# @ne study reported increased muscle

activity but did not assess voluntary activation as aproportion of involuntary activation <e#g# using aninterpolated twitch># &his study reported increasedmuscle activity in line with increased force production#In contrast, a different study that did measure truevoluntary activation found no changes as a result of the taper# It is therefore unclear whether any neural

activity changes occur as a result of tapering thatmight affect strength# &he reviewers also note that asmall number of studies have assessed potentialchanges in muscle architecture <fascicle length,pennation angle and physiological cross3sectionalarea> but these have all produced negative results#

What did the revie4ers conclude3&he reviewers concluded that tapering is effective forincreasing ma imal muscular strength temporarily fora competition# &hey conclude that all tapering formatsappear to be effective and that the literature currentlydoes not allow for the optimal tapering method to beidentified# &hey note that volume reductions of around8( + *(0 have been used with success and thatmaintaining high relative loads while reducing volumeseems to be the most beneficial strategy#

0imitations&he review was primarily limited by the small numberof studies that have been performed in this area#


http://journals.lww.com/nsca-scj/Abstract/2015/04000/Effects_and_Mechanisms_of_Tapering_in_Maximizing.3.aspx

http://journals.lww.com/nsca-scj/Abstract/2015/04000/Effects_and_Mechanisms_of_Tapering_in_Maximizing.3.aspx

8/18/2019 SCR_MAY_15_PDF


'hort term effect of crunch e"ercise fre(uency onabdominal muscle endurance/ by 3uan ;ecio/ ,<#ez=ivancos/ Moya/ 'arabia/ and =era +arcia/ in The

3ournal 9f '#orts Medicine )nd Physical 1itness4-5678

BackgroundEffect of training fre(uency on strength gains;urrently, the evidence indicates that training withdifferent volume3matched fre$uencies over the courseof a wee% has little effect on strength gains inuntrained individuals# &his is on the basis of - long3term trials comparing C) training groups, of which allbut one reported no differences between groups# @nthe other hand, the evidence indicates that trainingwith a higher volume3matched fre$uency mightpossibly be superior to training with a lower volume3matched fre$uency for increasing strength in trainedindividuals# However, this is on the basis of 8 long3term trials comparing C) training groups, of which .

reported a benefit in favor of training with a higherfre$uency for at least one of the outcome measuresfor strength while the other ) trials reported nodifferences between groups#

/ore detail

Effect of training fre(uency on size gains;urrently, the evidence indicates that training withdifferent volume3matched fre$uencies over the courseof a wee% has little effect on gains in muscular si e inuntrained individuals# &his is on the basis of = long3term trials comparing C) training groups, of which allbut one reported no differences between groups# @nthe other hand, the evidence indicates that training

with a higher volume3matched fre$uency mightpossibly be superior to training with a lower volume3matched fre$uency for increasing muscular si e intrained individuals# However, this is on the basis of 8long3term trials comparing C) training groups, of which . reported a benefit in favor of training with ahigher fre$uency for at least one of the outcomemeasures of muscular si e while the other ) trialsreported no differences between groups#

/ore detail

*B+EC,I-E. &o compare the effects of training usingthe crunch e ercise ., ) or 8 days per wee% onabdominal muscle endurance <as measured by thebench trun% curl, which involved performing thema imum number of upper trun% fle ion repetitionspossible in a ) minute period>, in untrained adolescentsubjects#

P*P/0A,I*1. ..9 untrained high3school students< ? males and ? females aged G .-#?9 L .#.*years>, randomly allocated into groups training . dayper wee%, ) days per wee%, 8 days per wee%, or anon3training control group#

I1,E -E1,I*1. Each training group performed awor%out involving the crunch and cross3crunche ercises ., ) or 8 days per wee% for a period of -wee%s# Each wor%out involved ) sets of each e ercise,with 8( seconds of rest between sets#

What ha))ened3

%ench trun& curl test #erformance&he researchers found that the ., ), and 8 day perwee% groups all improved bench trun% curl testperformance significantly but there were no significantdifferences between the groups# &he performanceincreases in each of the ., ), and 8 day per wee%groups were7 ).# 0, .8# 0, and .=#=0, respectively#

What did the researchers conclude3&he researchers concluded there was no differencebetween the groups training ., ), or 8 days per wee%in the increase in abdominal muscle endurance, asmeasured by the bench trun% curl test# &hey thereforesuggested that a small amount of crunch training <.

day per wee%> might be sufficient for increasingabdominal muscle endurance in adolescents#

0imitations&he study was limited as strength was not measuredand therefore it is unclear whether this metric wasaffected by the training program#






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The effect of long term isometric training oncore>torso stiffness/ by ,ee and Mc+ill/ in The 3ournal of 'trength Conditioning ;esearch 4 -567 8

Background;ore stability has been subject to a large amount of

research, both with a view toward improving athleticperformance and to preventing and treating low bac%pain <6 P># However, in the literature, there has beenconsiderable variety between studies in respect of what is defined by both the core and by stability#/oreover, stability re$uirements may differ underdifferent loading conditions, particularly as the corecan be subject to indirect forces applied from a varietyof different directions and also in response to forces of varying durations and magnitudes# &hus, the conceptof core stability is e tremely difficult to pin downaccurately# ;ore stability is thought to be importantfor athletes because of the transfer of force from theupper body segments to the lower body and from thelower body segments to the upper body in a processcalled se$uential %inetic lin%ing# 1esearchers havepreviously outlined how the acts of baseball pitchingand batting follow a se$uential %inetic chain# &hisphenomenon describes motions that follow a pro imal3to3distal pattern, which are initiated by larger, centralbody segments and then proceed outward to thesmaller, more distal segments, such as the arms#Where optimal pro imal3to3distal %inematic se$uencesoccur in throwing motions, the pelvis is rotated usingthe leg and hip muscles# &he pelvis initially acceleratesbut then $uic%ly decelerates as it transfers energy tothe torso# &he same pattern is repeated with the torsoand the arm and then the arm and the hand or bat#:uring this se$uence, it is thought that the activationof the core muscles acts to decelerate pelvic rotationand accelerate rotation of the upper trun%# "ot allresearchers have considered the important role of thetrun% muscles in such se$uences when attempting todefine core stability for athletes# /any genericdefinitions have been proposed defining core stabilityas the integrated functioning of the spine andsurrounding muscles to maintain intervertebral rangeof motion within a safe limit# Such definitions fall shortnot only of ta%ing the role of the trun% in athleticmovement into account but also in that they e cludethe abdominal musculature <with the %ey ones beingthe transverse abdominis, rectus abdominis, e ternalobli$ue, and internal obli$ue>, which are also thought

to have a %ey role in core stability# In possibly themost important definition of core stability, Nibler et al#<)((- > described it as OOthe ability to control theposition and motion of the trun% over the pelvis toallow optimum production, transfer and control of force and motion to the terminal segment inintegrated athletic activities#B "evertheless, it is highlyli%ely that the current failure to uncover meaningfulfindings in this area of research is at least partlycaused by the failure to define terms appropriately#

*B+EC,I-E. &o compare the long3term effects of dynamic and isometric training methods on changes inactive and passive core stiffness in untrained andtrained athletes# 'ctive stiffness was measured byreference to a $uic% release trial# &he subjects sat in asemi3seated position in a restraint jig that restrictedhip and lower limb motion but left the trun% free to

move in all directions# &he subjects were then pre3loaded with a .-%g mass, which was then removedwithout notice# &he subjects used bracing techni$uesto reduce movement upon the release of the mass#Passive stiffness was measured through sagittal,frontal, and transverse plane passive bending trials ina special apparatus in which subjects were secured atthe hips, %nees and an%les on a solid lower bodyplatform# Subjects were encouraged to rela while theapparatus performed certain limited range of motionmovements#

P*P/0A,I*1. )= healthy, males <aged )8 L 8 years>comprising .) untrained subjects and .) /uay &haiathletes#

I1,E -E1,I*1. &he subjects performed eitherisometric or dynamic e ercises for a -3wee% period#&he isometric group used bracing cues during theire ercises# &he isometric e ercises included the plan%,bird dog, side plan%, Pallof press, and inverted row#&he dynamic e ercises included the superman, sidecurl up, twisting curl up, bac% e tension, and lateraland rotational medicine ball throws#

What ha))ened3

)ctive stiffness"o significant changes in active stiffness were found ineither trained or untrained subjects following eitherthe isometric or dynamic protocols#

Passive stiffness&he researchers found that passive stiffness increasedin both groups for several measures, although thenumber of measures that increased and the si e of theincreases was smaller in the dynamic group than inthe isometric group#

What did the researchers conclude3&he researchers concluded that isometric training issuperior for increasing passive core stiffness incomparison with dynamic training, although neithertype of training appear to be able to increase active

stiffness#

0imitations&he study was limited in that it is unclear whatunderlying mechanisms are responsible for theobserved changes in core stiffness in each traininggroup and whether they are similar or different#


http://pdfs.journals.lww.com/nsca-jscr/9000/00000/The_Effect_of_Long_Term_Isometric_Training_on.96950.pdf


http://pdfs.journals.lww.com/nsca-jscr/9000/00000/The_Effect_of_Long_Term_Isometric_Training_on.96950.pdf


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)cute effects of antagonist static stretching in theinter set rest #eriod on re#etition #erformance and muscle activation/ by Miranda/ Maia/ Paz and Costa/ in;esearch in '#orts Medicine 4 -567 8

Background

2le ibility is important for both athletes and for thegeneral population# 2le ibility is defined as the abilityto move through a specific joint range of motion<1@/># Stretching is commonly used to helpindividuals achieve greater joint 1@/# 1esearchershave generally proposed two types of mechanism bywhich increases in fle ibility can be achieved# @netype of mechanism involves a mechanical change inthe behavior of the muscle tissue while the other typeinvolves a change in sensation# However, there are atleast four theories that detail ways in which some %indof mechanical change could occur7 viscoelasticdeformation, plastic deformation, increased number of sarcomeres in series, and neuromuscular rela ation#However, the evidence to support these has beenfound to be wea%# In contrast, many studies havereported that the only variable that changes followingstretching programs in tandem with fle ibility is thesensation of pain <i#e# ma imum pain and onset of pain> during the stretch# &his supports the sensationtheory of stretching# 1esearchers advocating thistheory have formulated the hypothesis that stretchingincreases fle ibility by reducing the sensation of increasing muscle length# "evertheless, irrespective of how stretching changes joint fle ibility, it is apparentthat it can achieve increases in joint 1@/ that last C .day# &here are two main types of stretching that aree plored in the literature7 static and dynamicstretching# Static stretching involves moving a joint tothe end of its 1@/ and holding this stretched positionfor a set period of time# @n the other hand, dynamicstretching involves controlled movements through theactive 1@/ for a joint# While both static and dynamicstretching have been found to improve joint 1@/,static stretching performed for C= seconds appearsto lead to meaningful acute reductions in performancetas%s, such as vertical jumping, whereas dynamicstretching performed for long durations appears tolead to either no improvement or small improvementsin the same type of actions# It is interesting to notethat reviews of the chronic effects of static stretchinghave actually found beneficial effects on both athleticperformance and strength measures# &he literature is

currently conflicting regarding whether regular staticor dynamic stretching is effective for reducing the ris%of sports injury, whether the stretching is performedimmediately prior to e ercise or at another time#'dditionally, the e act duration of stretches, the totalvolume and fre$uency of stretching per wee%, and therest periods between stretches that are optimal for themost efficient increases in joint 1@/ are currentlyun%nown#

*B+EC,I-E. &o e plore the effects of static stretchingof the antagonist muscles during the inter3set restperiod on the number of repetitions performed and onthe muscle activation of the biceps brachii, pectoralismajor and latissimus dorsi muscles <as measured byelectromyography JE/4K>, in trained subjects#

P*P/0A,I*1. .( trained male subjects <))#= L (#?years>#

I1,E -E1,I*1. &he subjects performed 8 sets of the seated row e ercise with .(1/ to muscular failurewith a )3minute inter3set rest period# In one condition,the subjects rested passively during the inter3set restperiod# In another condition, a researcher applied apassive stretch to the pectoralis major muscles for =(seconds during the inter3set rest period#

What ha))ened3

Number of re#etitions&he researchers found that passive stretching of the

antagonist muscles in the inter3set rest periods led toa significant increase in the number of repetitions thatwere performed in set . <?#? L (#8 vs# ..#. L (#?repetitions>, in set ) <?#) L (#- vs# .(#- L .#(repetitions>, and in set 8 <9 L (#- vs# ?#- L (#repetitions># &he increase in repetitions in each set ledto a greater overall training volume being performedin the condition that involved passive stretching of theantagonist muscles#

EM+ activity &he researchers found significant increases in the E/4activity of the latissimus dorsi and biceps brachii in thecondition involving passive stretching of the ant3agonist muscles compared to the control condition#

What did the researchers conclude3&he researchers found that passive stretching of theantagonist muscles during the seated row e ercise ledto a significant increase in the number of repetitionsperformed as well as increased muscle activity of thelatissimus dorsi and biceps brachii muscles#

0imitations&he study was limited in that it is unclear whether thesame effect would be observed in other muscle groupsand for other e ercises# It was also limited in that it isunclear whether the findings could be replicated byactive stretching of the trainee themselves#


http://www.tandfonline.com/doi/abs/10.1080/15438627.2014.975812


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Im#act of limited hamstring fle"ibility on vertical !um#/ &ic&ing s#eed/ s#rint/ and agility in youngfootball #layers/ by +arc?a Pinillos/ ;uiz )riza/ Moreno0el Castillo/ and ,atorre ;om@n/ in 3ournal of '#orts'ciences 4 -567 8

BackgroundSoccer or 'ssociation 2ootball is the world s mostpopular team sport and is played by more than ) (million people in over )(( separate countries# &hroughthis incredible popularity, it is %nown simply as

AfootballB in most parts of the world, despite thee istence of many other football codes, including'merican 2ootball, 'ustralian 1ules 2ootball, 4aelic2ootball, and 1ugby# Soccer is played in teams of ..players in two halves of = minutes in length with a. 3minute brea% between the two halves# Play runscontinuously within halves, such that the cloc% is notstopped while the ball is out of play# &here is usually a. 3minute half3time brea% between halves# Every fouryears, the World ;up is held, in which around )((national teams compete in $ualifying tournaments inthe hope of becoming one of the 8) national teamsthat compete in the =3wee% competition# &he mostrecent World ;up was held in ra il and was thetwentieth such competition# 4ermany beat 'rgentina.+( in the final to ta%e their fourth title# &raining forsoccer re$uires a focus on many different aspects,including physical $ualities, technical s%ills, andtactical abilities# &here are many different physical$ualities that are important for soccer, includingaerobic endurance, anaerobic endurance, strength,power and fle ibility# &raditionally, soccer teams placedthe most emphasis on aerobic endurance, noting thatplayers needed to be able to run long distances duringgames# Indeed, there is a basic agreement that soccerplayers travel around ? + .=%m in a single ?(3minutematch, although the e act distance depends on theposition played# &raining methods for improvingaerobic capacity include interval training, small3sidedgames, game simulations, soccer3specific circuits,repeated sprints, and agility drills# /ore recently,soccer teams have begun to focus more on sprintrunning ability, which appears to be crucial in allowingsoccer athletes to dominate situations during play#&his change in focus came out of the reali ation thatthe nature of the activity performed by soccer playersduring a game comprises long periods of low3intensitywal%ing or jogging, interspersed by short periods of

ma imal or near3ma imal effort, including acceleratingsprints# Some studies have found that players performmany such accelerating sprints per match, for a totaldistance of around )((m# Sprint running ability can beimproved by various training methods, includingsprinting, heavy load resistance3training, ballisticresistance3training, plyometrics, and assisted andresisted sprinting# &here is currently no strongconsensus around which type of training is best,although a recent meta3analysis concluded that noviceathletes benefit most from sprint running practice andmore advanced athletes benefit more from a variedprogram#

*B+EC,I-E. &o assess the impact of limitedhamstring fle ibility <as measured by the unilateralpassive straight3leg raise test> on sprint running speedover m, .(m and )(m, countermovement jumpheight, agility <as measured by the alsom agilitytest>, and ball speed during %ic%ing with the dominantand non3dominant legs in young soccer players#

P*P/0A,I*1. =8 male football players <aged .= +.9 years> from a semi3professional football academy,allocated into two groups based on performance in thehamstring fle ibility test7 fle ible and infle ible#

What ha))ened3

0ifferences between grou#s&he researchers reported no differences between thetwo groups in relation to age, height, body mass, andbody mass inde # However, they reported that thegroup with superior hamstring fle ibility displayedsuperior sprint running ability over m <by -#.0>,over .(m <by =#.0> and over )(m <by 8#80># &hey

noted that the fle ible group also displayed superioragility as measured by the alsom agility test <by=#.0>, greater counter3movement jump height <by.(# 0>, and greater ball speed during %ic%ing withboth the dominant <by -#?0> and non3dominant <by9#(0> legs#

What did the researchers conclude3&he researchers concluded that hamstring fle ibility isimportant for sprint running performance, jumpingability, agility, and ball speed during %ic%ing in youngsoccer players#

0imitations&he study was limited as it was cross3sectional andtherefore does not establish whether improvingfle ibility would improve sprint running, jumping,agility or ball speed during %ic%ing in soccer athletes#




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alf s(uat or !um# s(uat training under o#timum #ower load conditions to counteract #ower and s#eed decrements in %razilian elite soccer #layers during the

#reseason/ by ,oturco/ Pereira/ *obal/ Aanetti/ +il/*itamura/ and Na&amura/ in 3ournal of '#orts'ciences 4 -567 8


AfootballB in most parts of the world, despite thee istence of many other football codes, including'merican 2ootball, 'ustralian 1ules 2ootball, 4aelic2ootball, and 1ugby# 2or an introduction to soccer andthe re$uirements of this popular sport, please see thepreceding study review#

*B+EC,I-E. &o compare the effects of jump s$uatand half3s$uat training on the e pected reductions insprint running performance <as measured over m,.(m and )(m>, vertical jumping ability <as measuredby both s$uat and countermovement jump heights>,and power output during jump s$uats and half s$uatsthat tend to occur following a =3wee% pre3season

training period in soccer players#

P*P/0A,I*1. )8 elite male soccer players, randomlyallocated into two groups7 jump s$uat <aged )8#= L8#- years> and half s$uat <aged )=#. L #) years>#

I1,E -E1,I*1. &he soccer players performed .(power oriented training sessions during a =3wee%, pre3season training period# In sessions . + =, the jumps$uat and half s$uat groups both performed - sets of 9 repetitions with the jump s$uat or half s$uate ercise using the optimum load for power# Insessions + *, the groups used - sets of - repetitionswith .#( times the optimal load for power# In sessions9 + .(, the groups used .#.( times the optimal load

for power# 1est periods of ) minutes were ta%enbetween each set#

What ha))ened3

=ertical !um#ing ability oth jump s$uat and half s$uat groups increased

s$uat jump height but the increase in the jump s$uatgroup was trivial, while the increase in the half s$uatgroup was moderate <.#)0 vs# #90># &he changes inboth groups in respect of countermovement jumpheight were trivial <(#=0 vs# 3.#)0>#

Power out#ut during !um# s(uats and half s(uats&he changes in power output during jump s$uats by

the jump s$uat and half s$uat groups were minimal<(#(0 vs# (#.0># However, there were moderatedecreases in half s$uat power output in both traininggroups <.)# 0 vs# *#?0>#

'#rint running s#eed and acceleration1eductions in the jump s$uat and half s$uat groupsoccurred for all measures of sprint running speed < m,.(m and )(m>, with the largest reductions occurringin both groups over m# 1eductions in both the jumps$uat and half s$uat groups occurred for all measuresof sprint running acceleration < m, .(m and )(m>,with the largest reductions occurring in both groupsover ( + m and over + .(m compared to over .( +)(m# However, the reduction in the jump s$uat groupover ( + m was small but the reduction in the half s$uat group was moderate#

What did the researchers conclude3&he researchers concluded that the half s$uat appearsto be more beneficial for protecting s$uat jump abilitywhile the jump s$uat appears to be more beneficial forpreventing reductions in sprint running accelerationover very short distances#

0imitations&he study was limited as it was performed over a veryshort period of time <= wee%s>#




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Training for #ower and s#eed: effects of increasing or decreasing !um# s(uat velocity in elite young soccer

#layers / by ,oturco/ Na&amura/ *obal/ +il/ Cal/Cuniyochi/ and ;oschel/ in The 3ournal of 'trength Conditioning ;esearch 4 -567 8


AfootballB in most parts of the world, despite thee istence of many other football codes, including'merican 2ootball, 'ustralian 1ules 2ootball, 4aelic2ootball, and 1ugby# 2or an introduction to soccer andthe re$uirements of this popular sport, please see thepreceding but one study review#

*B+EC,I-E. &o compare the effects of two differentvelocity3based jump training programs involving eitherincreasing or decreasing the jump s$uat velocity <byincreasing or reducing the e ternal load> on counter3movement jump height, mean propulsive velocity inthe jump s$uat, .1/ leg press, sprint runningperformance <over m, .(m and )(m> and agility <as

measured by the ig3 ag change of direction <;@:>test>#

P*P/0A,I*1. )= elite under3)( soccer players,randomly assigned to an increased bar velocity groupor a reduced bar velocity group#

I1,E -E1,I*1. 'll subjects performed a -3wee%period of jump s$uat training in a Smith machine,training 8 times per wee%# &he increased bar velocitygroup trained using jump s$uats with some loadremoved using elastic bands in order to increase barspeed by )(0# &he reduced bar velocity group trainedusing added load to the Smith machine <mean e traload G =.#= L ?# %g> in order to reduce bar velocity

by )(0 from baseline# Delocities in the increased andreduced bar velocity groups were .#-8 L (#..mQs and.#(9 L (#(*mQs, respectively#

What ha))ened3

,eg #ress 6;M strength&he researchers reported that although both groupsincreased leg press .1/ strength significantly, theincrease in the increased bar velocity group wasgreater than in the reduced bar velocity group <9#80vs# #=0>#

Countermovement !um# height oth groups increased countermovement jump height

significantly but there was no difference between thetwo groups#

'#rint running s#eeds&he increased bar velocity group increased sprintrunning speeds over m, .(m and )(m but thereduced bar velocity group only increased sprintrunning speed over )(m only# ;hanges in theincreased bar velocity group were greater over m<9#)0 vs# )# 0>, .(m <-#.0 vs# .#?0> and )(m<-#(0 vs# )#)0>#

)gility oth groups increased ;@: test performance and

there was a non3significant trend for the increased bar

velocity group to increase to a greater e tent thanthe reduced bar velocity group <-#80 vs# )#?0>#

What did the researchers conclude3&he researchers concluded that increasing bar velocityduring jump s$uat training was superior for increasingsprint running and agility performance while ma imumstrength was enhanced to a greater e tent byreducing velocity#

0imitations&he study was limited as it is unclear whether thesedifferences would occur when training C- wee%s#


http://pdfs.journals.lww.com/nsca-jscr/9000/00000/TRAINING_FOR_POWER_AND_SPEED___EFFECTS_OF.96952.pdf

http://pdfs.journals.lww.com/nsca-jscr/9000/00000/TRAINING_FOR_POWER_AND_SPEED___EFFECTS_OF.96952.pdf

8/18/2019 SCR_MAY_15_PDF


'#ort s#ecific training targeting the #ro"imal segments and throwing velocity in collegiate throwingathletes/ by Palmer/ Bhl/ owell/ ewett/ =iele/ and Mattacola/ in 3ournal of )thletic Training 4 -567 8

Background

&hrowing is a %ey feature of human behavior andappears to be one of the factors differentiating usfrom other primates# Evidence for hominids ta%ingpart in throwing activities stretches bac% before thee istence of homo sapiens and these facts suggestthat throwing may have played some role in theevolution of modern humans, potentially through itsbenefit for hunting and the conse$uent provision of food or in defense against predators# In modern times,throwing is now a %ey action in many sports, including'merican 2ootball, rugby, baseball, bas%etball andcric%et# 'thletes who compete in these sports oftendevote considerable effort to being able to throw withgreater force and accuracy# 2rom the layman sperspective, throwing is an activity that almoste clusively involves the arm and shoulder# However,researchers investigating the biomechanics of suchmovements have uncovered that the act of throwinginvolves the whole body in a se$uential %inetic chain#&his phenomenon is where joint angular motionsfollow a distinctive pro imal3to3distal pattern of activity# /ovements are initiated by larger, centralbody segments and then proceed outward to thesmaller, more distal segments, such as the arms andhands# Where optimal pro imal3to3distal %inematicse$uences occur in throwing motions, the pelvis is firstrotated as a result of force produced by the leg andhip muscles# &he pelvis therefore initially acceleratesbut then $uic%ly decelerates as it transfers this %ineticenergy to the torso# &he same pattern is repeatedwith the torso and the arm, and then the arm and thehand, ultimately resulting in the object being thrown#&he e act factors that are associated with optimalthrowing ability are unclear but may include theprecise co3ordination of the se$uential %inetic chain,the strength of the %ey muscles involved, the ability tostore elastic energy in the shoulder joint during recoil,and also the ma imum and actual ranges of motion<1@/> of each of the joint angles involved#

*B+EC,I-E. &o compare the effects of a core muscleendurance3training program and a sport3specificpower3training program on the change in pea%throwing velocity <normali ed for bodyweight> as wellas on the change in chop3and3lift power output<normali ed for bodyweight>#

P*P/0A,I*1. =- healthy, "ational ;ollegiate 'thletic'ssociation :ivision III athletes <age )( L .#8 years>,comprising .* female softball athletes and )? malebaseball players, randomly allocated into either atraditional endurance3training group or a power3stability+training group#

I1,E -E1,I*1. &he subjects trained for * wee%susing different programs# &he traditional core muscleendurance3training group and the power3stability+training group# &he core muscle endurance3traininggroup training was designed to improve spinalstabili ation and involved plan% variations<prone,supine, side>, superman, curl3ups, dead bugs, andbird dogs# &he power3training program also involved

spinal stabili ation but emphasi ed multi3planar,rotational e ercises targeting the pro imal segmentsin a way that is sport3specific to throwing# E ercisesincluded seated3to3standing rotation, in3line lungeweighted3rotation, and standing weighted3rotation#

What ha))ened3

Pea& throwing velocity &he power3training group increased throwing velocityto a greater e tent than the core endurance group#&he core endurance group increased throwing velocityfrom .(9#-) L .9#-. to .(9#8( L .9#9.%mQhr whilethe power3training group increased from .(9#8( L).#=. to ..8#*. L ) .#=.%mQhr#

Cho# and lift #ower out#uts&he power3training group increased chop poweroutput to a greater e tent than the core endurancegroup# &he core endurance group increased choppower output from 8- L )() to * L .??W whilethe power3training group increased from .. L )(- to-.- L ))=W# Similarly, the power3training groupincreased lift power output to a greater e tent thanthe core endurance group# &he core endurance groupincreased lift power output from ) 9 L .)- to 8(9 L..9W while the power3training group increased from)=9 L .)9 to 8-) L .- -W#

What did the researchers conclude3&he researchers concluded that a sport3specific power3training regimen targeting the pro imal segments wassuperior to a traditional core endurance trainingroutine for improving both throwing velocity andpower output during the chop and lift test#

0imitations&he study was limited in that it is unclear to whate tent the training program was affected by theinclusion of the various e ercises involved#


http://www.natajournals.org/doi/abs/10.4085/1062-6040-50.1.05

http://www.natajournals.org/doi/abs/10.4085/1062-6040-50.1.05

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Peri#heral heart action 4P )8 training as a valid substitute to high intensity interval training toim#rove resting cardiovascular changes and autonomic ada#tation/ by Piras/ Persiani/ 0amiani/Perazzolo/ and ;affi/ in Euro#ean 3ournal of )##lied Physiology 4 -567 8

BackgroundInterval training was first developed by trac% and fieldathletes in the middle of the last century to helpimprove middle3 and long3distance runningperformance# &rac% running performance, li%eperformance in other endurance sports, is dependentupon three main physiological factors7 aerobiccapacity, lactate threshold, and wor% economy#&ogether, these variables can e plain the largemajority of the difference in endurance performancebetween individuals in both heterogenous <varied> andhomogenous <similar> groups# In contrast, each of thevariables alone is only able to e plain the majority of the difference in endurance performance between theindividuals in heterogenous groups# 'erobic capacity ismeasured using D@)3ma , which is the volume of o ygen that the body can ta%e in and use effectively ina given period of time, usually measured relative tobodyweight as mlQ%gQmin# 6actate threshold ismeasured by reference to blood lactate# :uring anincremental e ercise test, blood lactate initiallyremains close to its resting value# 't a certain e erciseintensity, however, it rises above the resting value andthis e ercise intensity is called the lactate threshold#1unning economy <strictly wor% economy if includingother e ercise modalities> is a measurement of theefficiency of the athlete# Economy is most commonlydescribed in terms of how much o ygen it ta%es to runa given distance at a given speed# &raditionally, thee clusive method for developing enduranceperformance was steady3state e ercise# Indeed,researchers have found that steady3state e ercise canimprove endurance performance in untrainedindividuals# However, improvements in already well3trained individuals are small# ;onse$uently, studiese ploring the effects of steady3state e ercise intrained subjects have often failed to find significantincreases in endurance performance or in any of theunderlying physiological factors <aerobic capacity,lactate threshold, and wor% economy># /ore recently,high3intensity interval training <HII&> has beendeveloped as a tool for increasing endurance

performance# HII& can be broadly defined as repeated bouts of short3to3moderate duration e ercise <i#e# .(seconds to minutes> at an intensity greater than theanaerobic threshold# &hese e ercise bouts are dividedby short bouts of either low3intensity wor% orinactivity that allow either a partial or a full recovery#1esearchers have found that HII& can improveendurance performance in untrained individuals# &heincreases are often larger than those following fromsteady3state interventions of similar duration#/oreover, research has often found significantincreases in endurance performance in trainedindividuals following HII& e ercise interventions#

*B+EC,I-E. &o compare the effects of PeripheralHeart 'ction &raining <PH'&> and HII& on muscularstrength <as measured by reference to .1/ in each of the pectoral machine, %nee e tension machine, latpull3down, leg curl, shoulder press, and calf raisee ercises>, ma imal aerobic capacity <as measured bya cycle ergometer3based D@)3ma test> and on

autonomic regulation <as measured by time series of beat3to3beat intervals for heart rate variability <H1D>,and barorefle sensitivity>#

P*P/0A,I*1. .9 young adults <? females and ?males>, aged )= L 8 years, randomly allocated eitherto an HI& group or to a PH'& group#

I1,E -E1,I*1. oth groups performed 8( trainingsessions over a .)3wee% period# In each session, theHII& group performed intervals of .3minute hardeffort and )3minutes of easy cycling# &he .3minute of hard effort was performed at .((0 of D@)3ma # &hePH'& group performed = circuits of - resistancetraining e ercises7 pectoral machine, %nee e tension

machine, lat pull3down, leg curl, shoulder press, andcalf raise e ercises# In each circuit, . repetitions of each e ercise were performed with minimal restbetween each e ercise# &he only rest was the timere$uired to move between machines# Each circuit wasinterspersed with . minute of rest#

What ha))ened3

Ma"imal aerobic ca#acity 4=9- ma"8'lthough both groups increased D@)3ma , theresearchers found that the HII& group increased D@)3ma to a greater e tent than the PH'& group <.9#*0vs# 9#(0>#

Muscular strength&he researchers found that both groups increasedmuscular strength in the lower body e ercises but onlythe PH'& group increased muscular strength in theupper body e ercises#

)utonomic regulation&he researchers found that barorefle sensitivityincreased in both groups but showed a greaterincrease after HII& than after PH'& <.9#)0 vs#..#(0># &he researchers noted that while there weresignificant changes in H1D in both groups, there wereno significant differences between groups# However,they noted a non3significant trend for a reduction of mar%ers of sympathetic activity in the PH'& group<normali ed units of high vs# low fre$uency domains>but an increase of the same mar%ers in the HII&group#

What did the researchers conclude3&he researchers concluded that PH'& caused increasesin muscular strength and ma imal aerobic capacitywhile having potentially beneficial health effects onautonomic regulation#

0imitations&he study was limited in that the e tent to which H1Dcan be used to assess autonomic regulation is unclear#




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2% *IOMECHANICS AND MOTOR CONTRO+


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Control of #ro#ulsion and body lift during the first twostances of s#rint running a simulation study/ by 0ebaere/ 0elecluse/ )erenhouts/ agman/ and

3on&ers/ in 3ournal of '#orts 'ciences 4 -567 8

Background

Sprint running is a %ey athletic $uality that iscontested in its own right in trac% and field, as well asbeing critical for success in many team sports, such assoccer, rugby, and both 'ustralian 1ules and 'merican2ootball# ;onse$uently, many researchers haveperformed e tensive wor% into sprint running, bothoverall and in respect of certain specific aspects,including %inematics <joint angles> %inetics <forces andmoments>, stiffness, electromyographic <E/4>activity, and the transfer of training to sprint running#'s a result, there is a large body of %nowledge inrespect of the features that are characteristic of elitesprinters and also of the training methods that maylead to best results# Sprint running performance isdetermined by the combination of stride length andstride fre$uency# @bservational research indicates thatsome athletes rely on stride length for increasedspeed while others rely more on stride fre$uency forincreased speed# 'nalysis of biomechanics suggeststhat for improving stride length, hopping, boundingand stepping drills may be able to develop differentaspects of force production during the sprint runninggait cycle# 'nalysis of e perimental trials suggeststhat sprint training, resistance training, plyometricsand resisted sprint training all produce significantimprovements in stride length# &he effectiveness of plyometrics may be related to observations that thestorage of elastic energy is important for sprintrunning performance# Indeed, researchers have foundthat this elastic energy storage becomes moreimportant with increasing sprinting speed# &hisindicates that drop jumps and other verticalplyometric e ercises might be among the mosteffective training tools# Indeed, since biomechanicalanalysis suggests that the main role of the %neee tensors is one of shoc% absorption and increased

joint stiffness upon ground contac t, this furthersupports a role for reactive plyometric training thatstresses this muscle group, such as drop jumps#1elated to this idea are the results of musculos%eletalmodeling research, which has reported that thelimiting factor for sprint running performance ismuscle contraction velocity# &his suggests that training

rate of force development for the %ey running musclesmay be the single most important factor in developingsprint running performance# &his probably re$uires ami of training involving low loads with high velocities<which can be achieved using plyometrics> and highloads with low velocities# 2or improving stridefre$uency, both e perimental trials and biomechanicalanalysis indicate that combined heavy and e plosivetraining along with overspeed running, using either adownhill slope or towing are all effective#

*B+EC,I-E. &o e plore the contribution of lower body joint moments <measured using the combined dataproduced from a motion analysis system and fromforce plates> and the contribution of individual muscleforces <estimated by musculos%eletal modeling> to thevertical and hori ontal acceleration of the body centerof mass during the first two steps of a trac% sprint in

trained trac% sprinters#

P*P/0A,I*1. * well3trained sprinters <) males and females> aged .?#* L 8#(. years# &he males had

personal best times over .((m of ..#.(s and ..#**sand the range of times in females was .)#( + .)#8-s#

What ha))ened3

Contribution of !oint moments&hrough inverse dynamics, the researchers calculatedthe joint moments and found that the an%le joint of the stance leg contributed most to center of masshori ontal propulsion, contributing -*0 in the firststance phase and ?80 in the second stance phase# In

contrast, they found that all three joints contributedmore evenly to vertical lift of the center of mass in thefirst stance phase, with the hip, %nee and an%le jointseach contributing .)0, 890 and (0, respectively#However, the second stance phase only involved %neeand an%le joint moments, with contributions being)=0 and *-0, respectively#

Contribution of muscle forces&hrough musculos%eletal modeling, the researchersestimated the muscle forces and found that each of the an%le plantar fle ors of the stance leg appeared tocontribute similarly to hori ontal propulsion, with thegastrocnemius contributing ) 0 and )?0 in first andsecond stance phases and the soleus contributing8)0 and )*0 in the first and second stance phases#Similarly, they found that the an%le plantar fle ors of the stance leg appeared to contribute similarly tovertical lift, with the gastrocnemius contributing )(0and )=0 in first and second stance phases and thesoleus contributing 8-0 and )90 in the first andsecond stance phases#

What did the researchers conclude3&he researchers concluded that the an%le plantarfle ors are %ey muscles in driving sprint athletes outof the bloc%s at the start of a race, being the primarycontributors to joint moments during the first twosteps#

0imitations&he study was limited in that it was unclear to whate tent the joint moments were affected by the processof se$uential %inetic lin%ing, in which %inetic energy isproduced by pro imal segments and then transmittedto more distal segments in order to produce a moreefficient and powerful co3ordinated action#




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'elected determinants of acceleration in the 655ms#rint/ by MaD&a a/ 1ostia&/ and *owals&i/ in 3ournal of uman *inetics 4 -567 8

BackgroundSprint running is a %ey athletic $uality that is

contested in its own right in trac% and field, as well asbeing critical for success in many team sports, such assoccer, rugby, and both 'ustralian 1ules and 'merican2ootball# 2or an introduction to sprint running and therelevant research regarding this athletic movement,please see the preceding study review#

*B+EC,I-E. &o e plore the associations betweenmuscular strength <as measured by .1/ bac% s$uatand iso%inetic trun% fle ion tor$ue> jumping ability <asmeasured by standing long jump, standing 3jumps,and standing .(3jumps> and both accelerating sprintspeed <as measured by .(m speed> and ma imalsprint speed <as measured by 8(m speed> in well3

trained trac% sprinters#

P*P/0A,I*1. )) male subjects, aged ).#* L .#(9years, including .. competitive male sprinters, with amean personal best time of .(#?- L (#8-s for .((mtrac% sprint, and .. recreationally trained students,with a mean personal best time of .)#)( L (#8?s for.((m with ..#9(s fastest time>#

What ha))ened3

Correlations with 65m and F5m s#rint s#eedsIn the trac% sprinters, the researchers reported strongcorrelations between .(m sprint speed and thefollowing performance tests7 standing long jump <r G

(#**>, standing 3jump <r G (#-->, standing .(3jump<r G (#*)>, and .1/ bac% s$uat <r G (#--># However,8(m sprint speed was only strongly correlated withthe following performance tests7 standing long jump <rG (#-9> and standing .(3jump <r G (#-)># Stridelength and stride fre$uency measured over .(m werenot correlated with .(m sprint time# However, stridefre$uency measured over 8(m was correlated with8(m sprint time <r G 3(#9)>#

Correlations with 655m s#rint s#eed In the trac% sprinters, the researchers similarlyreported strong correlations between .((m sprintspeed and the following performance tests7 standinglong jump <r G (#9)>, standing 3jump <r G (#9(>,standing .(3jump <r G (#98>, and .1/ bac% s$uat <rG (#*8># Stride length measured over .(m wascorrelated with .((m sprint time <r G 3(#-.> whilestride fre$uency measured over 8(m was correlatedwith .((m sprint time <r G 3(#-*>#

What did the researchers conclude3&he researchers concluded that in most cases, thehori ontal jumps <standing long jump, standing 3

jump, and standing .(3jump> were correlated stronglywith .(m, 8(m and .((m sprint running performance#&here was also a strong correlation between .1/ bac%s$uat and sprint running performance over all threemeasured distances#

0imitations&he study was limited in that it was cross3sectionaland therefore it is unclear whether the attributesdisplayed by the more successful sprinters werecausally related to their greater sprint running abilityor incidental#


http://www.degruyter.com/view/j/hukin.2015.45.issue-1/hukin-2015-0014/hukin-2015-0014.xml


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Physical #rinci#les demonstrate that the bice#sfemoris muscle relative to the other hamstringmuscles e"erts the most force im#lications for hamstring muscle strain in!uries/ by 0olman/ =errall/and ;eid/ in Muscles/ ,igaments and Tendons 3ournal 4 -567 8

Background6i%e the $uadriceps, the hamstrings muscle groupcomprises four individual muscles located on thethigh# However, the anatomy and muscle architectureof the hamstrings muscle group are much morecomple than those of the $uadriceps# &here are threetwo3joint hamstring muscles that cross both the hipand the %nee joints <which are the biceps femoris<long head>, semimembranosus, and semitendinosus>and one single3joint hamstring muscle that onlycrosses the %nee joint <the biceps femoris <shorthead>># &he two3joint hamstring muscles all have theirorigin on the ischial tuberosity of the pelvis# &hesingle3joint hamstring muscle has its origin on thelower half of the linea aspera and the lateral condyloidridge# &hus, three of the hamstrings perform both%nee fle ion and hip e tension and one performs only%nee fle ion# 'dditionally, the hamstrings can bedivided into lateral and medial muscles# &he lateralmuscles comprise the two heads of the biceps femoriswhile the semi3membranosus, and semitendinosus arethe medial muscles# &he lateral muscles insert on thelateral condyle of the tibia and on the head of thefibula, while the medial muscles insert on the medialsurface of the tibia and on the medial condyle# &hebiceps femoris <long head> is the largest hamstring byanatomical cross3sectional area but the semi3membranosus is the largest by weight andphysiological cross3sectional area# &he semitendinosushas the longest normali ed fiber length whencompared to the other hamstrings while thesemimembranosus has the greatest pennation angle#/uscles with more comple pennation arrangementstend to have shorter normali ed fiber lengths butlarger pennation angles and more fibers# &hesemitendinosus is the only hamstring muscle that isfusiform in shape# It has longitudinal muscle fibersthat are intersected by an intramuscular, tendinousseptum which separates the muscle into pro imal anddistal regions# In contrast, the semimembranosus ishemi3pennate# &he muscle fibers lie in a parallelarrangement, connecting the tendon at the origin on

the deep side and the tendon at the insertion on thesuperficial side of the muscle# &he biceps femoris<long head> is also hemi3pennate# &he muscle fiberslie in a parallel arrangement, connecting the tendon atthe origin on the deep side and the tendon at theinsertion on the superficial side of the muscle# &hebiceps femoris <short head> ta%es the form of atrape oid, with longer muscle fibers on the pro imalside and shorter ones on the distal side# Some groupsof researchers have suggested that the musclearchitectural arrangements of the hamstring musclesmay be important for identifying injury ris%#

*B+EC,I-E. &o calculate the relative forces of each of the two3joint hamstring muscles during a typicallengthening contraction as performed during runningmovements, by combining data from cadaver studiesregarding the muscle architecture of each muscle anddata from sprint running motion analysis studiesregarding the joint angle changes during running#

&hese data were incorporated into a single simplifiedmusculos%eletal, spring3based model for analysis#

What ha))ened3

amstrings muscle lengths&he researchers input the muscle lengths of thesemimembranosus, semitendinosus, and of the bicepsfemoris <long head> based on cadaver studies at)-#=cm, 8.#-cm, and )9#.cm, and total muscle3tendon lengths of ==#8cm, =8#?cm, and =8#9cm#

amstrings muscle elongations and forcesMsing their musculos%eletal model, the researcherscalculated that the stretch of the semimembranosus,

semitendinosus, and of the biceps femoris <long head>muscles was *#=0 <8#8cm>, 9#.0 <8#-cm>, and ?# 0<=#)cm>, respectively# &hey found that these increasesin length corresponded to muscle forces that were .#.times greater in the semitendinosus than in thesemimembranosus and .#8 times greater in the bicepsfemoris <long head> than in the semimembranosus#

What did the researchers conclude3&he researchers concluded that the additional changesin length that are re$uired of the biceps femoris <longhead> muscle during lengthening contractions asperformed during sprint running provide indirectsupport for its status as the most commonly3injured

hamstring muscle in sport#

0imitations&he study was limited as it was based upon thecreation of a simplified musculos%eletal model andmay have ignored certain assumptions or containederrors in the data used# 2or e ample, it may not bevalid to model muscles as individual, simple spring3mass systems#


http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4241430/


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*inematic and sEM+ analysis of the bac& s(uat at different intensities with and without &nee wra#s/ by +omes/ %rown/ 'oares/ 0a 'ilva/ 0e 9liveira 'ilva/'er#a/ and Marchetti/ in The 3ournal of 'trength Conditioning ;esearch 4 -567 8

Background&he bac% s$uat is an e ercise performed with a barbellresting on the upper trape ius# It is the standarde ercise for developing lower body strength and si efor both athletes and bodybuilders# ' great deal of research has been performed into the bac% s$uat#6ong3term trials have established that it is effectivefor improving lower body strength and power as wellas vertical jumping and sprint running performance#

iomechanics studies have found that there areseveral %ey e ercise techni$ue variables that ma%e adifference to the effect of the e ercise on the wor%ingmusculature# In particular, it has been found that theload has a more pronounced effect than s$uat depthon the force re$uired from the an%le plantar3fle ors,that depth is a more significant factor than load forthe force re$uired of the %nee e tensors, and thatboth depth and load are %ey for determining the forcere$uired from the hip e tensors# &hus, both s$uatdepth and load should be considered as variables inusing s$uats depending on which muscle groups are tobe strengthened and to what e tent# In terms of othertechni$ue variables, researchers have found thatstance width and foot position ma%e little difference tomost of the lower body muscles e cept the gluteusma imus# &herefore, despite the claims of somepopular strength coaches and bodybuilders, usingdifferent stance widths during s$uats are unli%ely todevelop different parts of the $uadriceps and stressingindividual $uadriceps muscles or different parts of the$uadriceps will li%ely re$uire more careful e erciseselection# However, using a wider stance does appearto increase gluteus ma imus activity during s$uats#

*B+EC,I-E. &o assess the acute effects of %neewraps on %nee and hip joint angle movements <asmeasured by a single camera system trac%ing thesagittal plane movements of 9 mar%ers placed on %eyanatomical locations> and on muscle activity of thevastus lateralis and gluteus ma imus <as measured byelectromyography JE/4K> during the bac% s$uat

e ercise at two different relative loads# E/4 activitydata were normali ed to ma imum voluntary isometriccontraction </DI;> levels#

P*P/0A,I*1. .= resistance3trained males, age )= L= years, with 8 L . years of bac% s$uat resistance3training e perience#

I1,E -E1,I*1. &he subjects performed . set of 8repetitions of the bac% s$uat to below ?( degrees of %nee joint fle ion# &here were = different conditions asthere were ) variables7 %nee wraps vs# no %nee wrapsand either low <-(0 of .1/> or high <?(0 of .1/>relative load#

What ha))ened3

Muscle activity &he researchers found that increasing the load from-(0 of .1/ to ?(0 of .1/ increased the E/4activity in both vastus lateralis and gluteus ma imusmuscles# Nnee wraps increased E/4 activity in bothmuscles at -(0 of .1/ but decreased E/4 activity inthe vastus lateralis at ?(0 of .1/ and left gluteusma imus E/4 activity unchanged at ?(0 of .1/#

3oint angle movements&he researchers found that increasing the load from-(0 of .1/ to ?(0 of .1/ led to significantlyreduced pea% hip fle ion angle in the no %nee wraps

condition and reduced pea% %nee fle ion angle in the%nee wraps condition# &hese reductions in joint anglewere accompanied by reduced vertical bar distancetraveled#

What did the researchers conclude3&he researchers concluded that increasing relativeload with and without %nee wraps during the s$uate ercise leads to increased muscle activity in thevastus lateralis and gluteus ma imus# &hey noted thatthe use of %nee wraps with high relative loads led toreduced muscle activation of the vastus lateralis butnot in the gluteus ma imus# &hey suggested that thisreduction in muscle activity might be caused by the

storage of elastic energy in the %nee wraps thatma%es the movement easier to perform#

0imitations&he study was limited in that only a single .1/measure was used <no %nee wraps> and also in thatthe researchers did not compare the level of muscleactivity between the vastus lateralis and gluteusma imus# &herefore, it is unclear whether using %neewraps caused a shift in the contribution of eachmuscle to the overall lift performance#


http://pdfs.journals.lww.com/nsca-jscr/9000/00000/KINEMATIC_AND_sEMG_ANALYSIS_OF_THE_BACK_SQUAT_AT.96969.pdf

http://pdfs.journals.lww.com/nsca-jscr/9000/00000/KINEMATIC_AND_sEMG_ANALYSIS_OF_THE_BACK_SQUAT_AT.96969.pdf

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,ower e"tremity strength and the range of motion inrelation to s(uat de#th/ by *im/ *won/ Par&/ 3eon/and Geon/ in 3ournal of uman *inetics 4 -567 8

Background&he bac% s$uat is an e ercise performed with a barbell

resting on the upper trape ius# It is the standarde ercise for developing lower body strength and si efor both athletes and bodybuilders# 2or an introductionto this e ercise, see the preceding study review#

*B+EC,I-E. &o ascertain whether fle ibility andmuscular strength are each associated with s$uatdepth <as measured using motion analysis software>#2le ibility was measured by reference to joint range of motion <1@/> of hip fle ion, hip internal rotation, hipe ternal rotation, an%le dorsifle ion with an e tendedand fle ed %nee joint, using a universal goniometer#

/uscular strength was measured by reference to two%ey stabili ing muscle groups using a hand3helddynamometer7 the hip fle ors and the an%le dorsi3fle ors# 'ssociations were calculated using Pearsonproduct moment correlations and multiple stepwiseregression analysis was performed to identify the %eyvariables associated with s$uat depth#

P*P/0A,I*1. .(. healthy, untrained subjects <-=males, aged ) #-? L #?8 years and 8* females,aged ).#? L )#.* years>#

What ha))ened3

Correlations between s(uat de#th and fle"ibility

&he researchers reported that in males there was asignificant, negative correlation between s$uat depthand hip fle ion 1@/, hip internal rotation 1@/, andan%le dorsifle ion 1@/ <with and without an e tended%nee># &he strength of the correlation ranged fromvery small to moderate <r G 3(#)= to r G 3(#-)># &heresearchers also reported that in females only an%ledorsifle ion 1@/ <with and without an e tended %nee>was significantly negatively correlated with s$uatdepth and these correlations were small <r G 3(#=? tor G 3(#=->#

Correlations between s(uat de#th and strength&he researchers reported that in males there was nocorrelation between muscle strength and s$uat depth#However, in females, they found a significant, negativecorrelation between an%le dorsifle or strength ands$uat depth <r G (#)9>#

Multi#le regression analysis&he researchers reported that their multiple regressionmodel found that an%le dorsifle ion with a fle ed %neeand hip fle ion 1@/ were significantly associated withs$uat depth in male subjects <13s$uared G (#==> andan%le dorsifle ion with an e tended %nee and an%ledorsifle or strength were significantly associated withs$uat depth in females <13s$uared G (#8)>#

What did the researchers conclude3

&he researchers concluded that an%le dorsifle ion 1@/with a fle ed %nee and hip fle ion are importantfactors for enabling deep s$uatting in males, whilean%le dorsifle ion with an e tended %nee and an%ledorsifle or strength are important factors for enablingdeep s$uatting in in females# &his may indicate thatincreasing an%le dorsifle ion 1@/, increasing hipfle ion 1@/, and increasing an%le dorsifle or strengthmight lead to improved s$uat depth#

0imitations&he study was limited as it is unclear whether anyinterventions involving the above recommendationscan actually improve s$uat depth#




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Effects of an unstable load on force and muscleactivation during a #arallel bac& s(uat/ by ,awrenceand Carlson/ in The 3ournal of 'trength Conditioning;esearch 4 -567 8

Background

Instability training has become a popular method forsimultaneously developing the core musculature aswell as certain prime movers# Indeed, researchershave found that when standard upper3 or lower3bodye ercises are performed under unstable conditions,this generally leads to increased core muscle activity,as measured by electromyography <E/4># However,acute studies e ploring the prime movers in lower3body e ercises have generally found that unstablevariations lead to lower E/4 activity than their stablee$uivalents# Similar studies investigating the primemovers during upper3body e ercises have foundslightly more conflicting results, with some studiesshowing benefits of instability training, others showingno benefit, and others showing a detrimental effect#However, ' recent long3term investigation found thatinstability training with a range of e ercises using asuspension device was able to produce similar gains instrength to a set of similar, stable e ercises for theupper3body and for the lower3body in previouslyuntrained males# &hus, it may be the case thatinstability training is similarly effective as traditionalresistance3training for the upper3 and lower3bodyprime movers in untrained subjects# Whether it iscapable of achieving similar gains in trainedindividuals, however, is uncertain#

*B+EC,I-E. &o compare the ground reaction forcesand muscle activity produced during a parallel bac%s$uat with and without an unstable load <usingweights suspended from the bar by an elastic band>,in trained subjects# 4round reaction forces weremeasured using a force plate and muscle activity of the rectus femoris, vastus lateralis, vastus medius,

biceps femoris, soleus, rectus abdominis, e ternalobli$ue, and erector spinae muscles was measuredusing E/4#

P*P/0A,I*1. . resistance3trained males, aged)=#) L 8#= years, with 9#.L =#8 years resistance3training e perience, and a .1/ parallel bac% s$uat of .8.#= L ).#=%g#

I1,E -E1,I*1. Subjects performed .( repetitionsof the bac% s$uat with -(0 of .1/ parallel bac% s$uatunder both stable and unstable conditions# S$uatdepth was standardi ed for each condition by havingsubjects touch a bo that was set to a height suchthat the crease at the hip was below the top of the

%nee#

What ha))ened3

Muscle activity &he researchers reported that the unstable conditionproduced significantly greater E/4 activity in thee ternal obli$ues, rectus abdominis, and soleusmuscles than the stable condition#

+round reaction forces&he researchers reported that the unstable conditionproduced significantly less pea% vertical groundreaction force, although this was a small absolutereduction <8#?0>#

What did the researchers conclude3&he researchers concluded that bac% s$uats performedwith an unstable load <in this case using weightssuspended from the bar by an elastic band> can beused to increase activation of the abdominal musclesand while pea% vertical ground reaction forces arereduced, the si e of the reduction is not substantial#

0imitations&he study was limited in that it is unclear how the loadused by the subjects in the unstable condition relatedto the .1/ bac% s$uat with an unstable load# &hedifferences between the unstable and stable conditionsmay therefore relate mainly to differences in relativeload#


http://pdfs.journals.lww.com/nsca-jscr/9000/00000/EFFECTS_OF_AN_UNSTABLE_LOAD_ON_FORCE_AND_MUSCLE.96947.pdf

http://pdfs.journals.lww.com/nsca-jscr/9000/00000/EFFECTS_OF_AN_UNSTABLE_LOAD_ON_FORCE_AND_MUSCLE.96947.pdf

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Effects of isometric (uadrice#s strength training at different muscle lengths on dynamic tor(ue #roductionby Noor&Hiv/ Nosa&a/ and %lazevich/ in 3ournal of '#orts 'ciences 4 -567 8

Background

/uscle architecture is the organi ation of the musclefibers within the muscle with respect to the line of pull# &he line of pull is the line drawn through theorigin and the insertion of the muscle# /usclearchitecture is one of the least well3researchedsubjects when it comes to how muscles wor%# :espitethis, most researchers regard it as the single mostimportant factor when it comes to determining amuscleRs function, force production capacity andcontraction velocity# /uscle architecture comprisesthree main aspects7 fiber or fascicle length, pennationangle, and physiological cross3sectional area <P;S'>#&ogether, these three factors can be used to describeany given muscle or muscle compartment# 2asciclelength is the average length of the muscle fascicleswithin the muscle# It is often used instead of the morecorrect measurement of muscle fiber length because itis far easier to calculate# ;hanges in fascicle lengthhave a mar%ed effect on the ability of a muscle toproduce force# &his is because longer fibers contract athigher velocities than shorter fibers# 6onger fasciclescontract more $uic%ly than shorter fascicles becauseall of the sarcomeres in a single muscle fiber contractat the same time# Since sarcomeres in a single musclefiber are arranged in series, this produces a greaterrelative reduction in si e from the same startinglength# Indeed, researchers have observed thatmuscle fascicle length tends to be longer in elite .((msprinters than long3distance runners as well as in less3well3trained sprinters# /uscle fiber length, or moreaccurately, normali ed fiber length, is the length of themuscle after correcting for the average length of thesarcomeres within it# &his normali ation process isused so that muscles can be compared even whenthey are stretched or contracted# 'n increase innormali ed fiber length therefore tells us that thenumber of sarcomeres in series has increased <by aprocess called sarcomerogenesis># Pennation angle isthe angle of the muscle fibers within the muscle withrespect to the angle of pull# /ost muscles containfibers that are at an angle of between ( + 8( degrees#Pennation angle is the aspect of muscle architecturethat changes most with training# 's the pennation

angle increases, more muscle fibers are able to fit intothe same anatomical cross3sectional area <';S'>,although the P;S' in fact increases, because this ismeasured at right angles to the line of pull# 'spennation angle decreases the force that each musclefiber can produce, increasing pennation angle istherefore a trade3off between increasing the numberof muscle fibers but reducing the mechanicaladvantage# It should therefore be clear that P;S' isnot $uite the same as ';S'# ';S' is measured atright angles to the angle of pull whereas P;S' ismeasured at right angles to the pennation angle#

*B+EC,I-E. &o compare the effects of isometrictraining at short <%nee angle between 8( to (degrees>, and long <%nee angle between *( to .((degrees> muscle lengths, on gains in muscularstrength <as measured by concentric %nee e tensionisometric and iso%inetic tor$ue at -(, ?(, .)(, .9(,)=( and 8(( degreesQs> and si e <as measured by

cross3sectional area and volume by way of magneticresonance imaging </1I> scans> and to assesswhether the changes in strength are associated withalterations in muscle fascicle length <as measuredusing 3mode ultrasound>#

P*P/0A,I*1. .- men, randomly allocated intoeither short <9 subjects> or long <9 subjects> groups#

I1,E -E1,I*1. Subjects trained 8 times per wee%for - wee%s, using a protocol of sets of ma imalvoluntary isometric contractions </DI;s> of secondsin duration per session, with a 3second inter3repetition rest and a -(3second inter3set rest#

What ha))ened3

Muscular strength/uscular strength, as measured by concentric %neee tension tor$ue at a range of iso%inetic velocities,increased significantly after training only in the longlength group <by .) + .80> and did not increase inthe short length group#

Muscular size and volume&he researchers reported that muscle si e and volumeincreased after training only in the long length groupand not in the short length group#

Muscle architecture&he researchers reported that the increase in vastuslateralis fascicle length increased in both groups < #=L =#?0> but this change was not correlated withchanges in strength <as measured by concentric %neee tension tor$ue> in either group#

What did the researchers conclude3&he researchers concluded that isometric training atlong muscle lengths caused significant increases inmuscular strength and si e whereas isometric trainingat short muscle lengths did not# However, both groupstraining at short and long muscle lengths causedsignificant increases in muscle fascicle length, whichwere not correlated with changes in strength#

0imitations&he study was limited as it was performed usingisometric muscle actions, which may not be directlycomparable to more conventional training methods,which typically involve dynamic movements#




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Inhomogeneous (uadrice#s femoris hy#ertro#hy inres#onse to strength and #ower training/ by Ear#/Newton/ Cormie/ and %lazevich/ in Medicine 'ciencein '#orts E"ercise 4 -567 8

Background

/uscular hypertrophy is the increase in cross3sectionalarea or si e of a muscle# 1egional hypertrophy wasoriginally defined as a change in the shape of a musclefor the purposes of bodybuilding# /ore recently, theterm has been used in sports and e ercise science torefer to differences in hypertrophy along the length of a muscle, where different sections may display greateror less increases in si e from one another# Suchdifferences in hypertrophy over sustained periods of time may lead to changes in the shape of a muscle#&here are two main mechanisms according to whichregional hypertrophy might occur# 2irstly, it has beensuggested that the compartmentali ation of musclescould mean that certain areas were activated toperform certain ranges of motion of a joint action orcertain movements at a joint where multiplemovements are possible <such as at the hip orshoulder># 2or e ample, a recent study of the gluteusmedius reported that, on the basis of anatomy andinnervation, the gluteus medius has potentially up to =compartments <anterior, anterior3middle, posterior3middle, and posterior># &hese compartments havedifferent nerve branches and varying pennation angles<F88#., F.8#), 3?#?, and 3)?# degrees>, whichmeans that they are best suited to slightly differenttas%s# Indeed, on the basis of the anatomy, it hasbeen proposed that the hori ontal arrangement of theposterior fascicles of the gluteus medius relative to thefemoral nec% means that they probably act primarilyto stabili e the head of the femur in the acetabulum#In contrast, the other fibers of the gluteus medius,which are arranged more vertically with respect to thefemur, are better positioned to perform hip abduction#Secondly, it has been observed that there aredifferences in muscle fiber type between one region of a muscle and another# &his could mean that differentrep ranges or muscle actions could provide differentstimuli to the varying regions# 2or e ample, someresearchers have noted that type I muscle fibers arepredominant in the deep vastus lateralis, while type IImuscle fibers are predominant in the superficial vastuslateralis# @ther researchers have noted differencesbetween regions from pro imal3to3distal as well as

between regions from deep3to3superficial# &his meansthat where different repetition ranges are used andthereby target different muscle fiber types, this couldlead to preferential growth in certain parts of amuscle# Indeed, researchers recently confirmed thatdifferences in electromyography <E/4> activity incertain parts of a muscle correlated with the increasesin muscular si e#

*B+EC,I-E. &o compare the effects of heavy3load3slow3speed with light3load3fast3speed strength trainingon regional hypertrophy within the $uadriceps <asmeasured by ultrasound, pro imally to distally>#

P*P/0A,I*1. 8- untrained males, randomlyallocated to = groups7 parallel3depth heavy s$uat

training <using loads of * + ?(0 of .1/>, parallel3depth jump s$uat training <using loads of ( + 8(0 of .1/>, volitional3depth <smaller range of motion thanparallel> jump s$uat training <using loads of ( + 8(0of .1/>, and a non3training control group#

I1,E -E1,I*1. 'll subjects trained 8 times perwee% for 9 wee%s using a non3linear, daily undulatingperiodi ation model#

What ha))ened3

Total (uadrice#s hy#ertro#hy 'll three training groups increased muscular si e of the $uadriceps summed across all regions similarly,

with the heavy, light <parallel> and light <volitional>groups increasing by around .= + . 0 in total#

;egional differences caused by relative load &he researchers found that the heavy and light<parallel> groups increased region3specific hypertrophysimilarly in the pro imal <. #= L *#*0 vs# ..# L9# 0>, middle <.8#8 L ?#*0 vs# .8#- L ?#-0> anddistal <. #= L *#=0 vs# .?# L .8#.0> regions of the$uadriceps# However, there was a non3significanttrend for the heavy group to increase the si e of thepro imal region to a greater e tent than the lightgroup, while there was a non3significant trend for thelight group to increase the si e of the distal region to agreater e tent than the heavy group# However, in

respect of the individual $uadriceps, there was asignificantly greater increase in the heavy group forthe vastus intermedius pro imally and for the vastusmedialis in the middle region compared to the lightgroup,

;egional differences caused by ;9M &he researchers found no differences in regionalhypertrophy between the two jump s$uat groupstraining with different s$uat depths#

What did the researchers conclude3&he researchers concluded that there was evidence of differences in the regional hypertrophy of the

individual $uadriceps muscles following s$uat trainingwith heavy loads and slow speeds compared to withlight loads and fast speeds# &hey proposed that thespecific changes in muscle si e at different musclelengths might be re$uired for force production atdifferent muscle lengths or at different joint anglepositions#

0imitations&he study was limited in that the findings in relation to1@/ are conflicting with the findings of previousliterature and it is unclear why this occurred#


http://europepmc.org/abstract/med/25811947


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Influence of bench angle on u##er e"tremity muscular activation during bench #ress e"ercise/ by ,auver/Cayot/ and 'cheuermann/ in Euro#ean 3ournal of '#ort 'cience 4 -567 8

Background

&he bench press is a difficult lift to progress and canbe uncomfortable for some lifters to train regularly#;onse$uently, many trainees ma%e use of differente ercises to train the same muscles, including benchpress variations <incline, decline, dumbbell, etc#> andmachines# &he research comparing the different benchpress e ercise variations is limited# However, studiesusing electromyography <E/4> have been performedsuggesting that the barbell bench press is superior tothe <Smith> machine bench press for developing theanterior and middle deltoids and these two e ercisesare similarly effective for developing the pectoralismajor and triceps brachii# 'dditionally, it has beenreported that the hori ontal bench press can be usedfor specifically targeting the lower part of thepectoralis major <i#e# the sternocostal head>, while thelower part of the pectoralis major <i#e# the sternocostalhead> can be further targeted by selecting a narrowrather than a wide grip# &he decline bench press canbe used for specifically wor%ing the very lowestportion of the pectoralis major, the lower sternocostalportion, although it does not appear to be e$uallyeffective for the upper part of the sternocostal portion#2urthermore, using a wide grip during bench pressvariations has been found to reduce the involvementof the triceps brachii, while using a narrow grip canincrease their involvement# 2inally, studies havereported that the use of unstable surfaces for benchpress variations, such as balance cushions or Swissballs, is not recommended, as it leads to reducedpotential for developing the pectoralis major andtriceps brachii although not for the anterior deltoids#In addition to the above research e ploring the E/4activity in the various muscles during different benchpress variations, researchers have also assessed thee act location of the stic%ing region# It has beenreported that the stic%ing region is very li%ely notcaused by adverse changes in the e ternal momentarms at either the shoulder or the elbow, nor bychanges in neural drive to the prime movers, asmeasured by E/4 activity# It has been speculated thatthe stic%ing region in the bench press is caused by thegradual reduction in stored elastic energy as a result

of the eccentric phase prior to the lift# However, thereis little evidence for this and it therefore re$uiresfurther investigation# It is possible that titin mayprovide very large amounts of passive elastic forcecontribution at the bottom of the lift and it is possiblethat the stic%ing region in the bench press starts atthe point where titin contribution to the concentricphase reduces significantly#

*B+EC,I-E. &o compare the muscle activity <asmeasured by E/4 with surface electrodes> of theupper and lower pectoralis major, anterior deltoid andtriceps brachii muscles during the concentric andeccentric phases of a free3weight barbell bench pressperformed at (, F8(, F= and +. degrees of benchangle# E/4 was normali ed to the levels observed

during ma imum voluntary isometric contractions</DI;s>#

P*P/0A,I*1. .= healthy, resistance3trained males,aged ).#= L (#= years#

I1,E -E1,I*1. &he subjects performed . set of -repetitions for each bench press condition at - 0 of .1/#

What ha))ened3

B##er #ectoralis&he researchers found that upper pectoralis majorE/4 activity was greater during F8( degree incline

bench <..*# L =?#)0> compared to during the +.degree bench <.()#- L )*#*0> across the wholeconcentric muscle action#

,ower #ectoralis&he researchers found that the E/4 activity of thelower pectoralis was greater during the +. degreebench <.((#= L #*0>, F8( degree bench <9-#- L=#90> and hori ontal bench <.((#. L #)0>compared to the F= degree bench <*.#? L =# 0>across the whole concentric muscle action#

)nterior deltoids&he researchers found that E/4 activity of theanterior deltoid was less during the +. degree bench< 9#8 L 8(#*0> than the hori ontal bench <*-#( L8*#(0>, F8( degree bench, <?(#? L ==#80>, and F=degree bench <?*# L 8?#80>#

Trice#s brachii &he researchers found that E/4 activity of the tricepsbrachii was greater in the F8( degree bench <..=#8 L)-#80> and F= degree bench <..*#9 L )9# 0>conditions compared to the +. degree bench <.()#)L )-# 0> condition# 'dditionally, they found that theF= degree bench <..*#9 L )9# 0> produced greaterE/4 activity compared to the hori ontal bench <.(-#(L )9#*0>#


&he researchers concluded that a hori ontal bench isoptimal for ma imi ing the muscle activity of both theupper and lower heads of the pectoralis major#

0imitations&he study was limited in that it was an acuteinvestigation and it is unclear how training for longperiods of time with each of the lifts would affect gainsin muscular strength and si e of the various differentmuscles#




8/18/2019 SCR_MAY_15_PDF


Training related changes in the EM+ moment relationshi# during isometric contractions: further evidence of im#roved control of muscle activation instrength trained men$ %y )marantini and %ru/ in

3ournal of Electromyogra#hy and *inesiology 4 -567 8

BackgroundElectromyography <E/4> is a commonly3used methodthat helps researchers understand how strongly amuscle is contracting# E/4 is performed using anelectromyograph in order to produce an output %nownas an electromyogram# 'n electromyograph detectselectrophysiological activation of a muscle during theproduction of mechanical force# E/4 is an importantmethod as it is not possible with current technology tomeasure forces inside a muscle# /usculos%eletalmodeling can provide an estimate of these forces butsuch values are based upon a variety of assumptionsand are indirect and not direct measurements#/easuring E/4 activity using an electromyographinvolves placing electrodes either on or in a muscle#Electrodes can be placed either upon the s%in <surfaceE/4> or directly into the muscle itself <fine wire E/4>#While fine wire E/4 is thought to provide a moreaccurate picture of the E/4 activity in a very specificpart of a muscle, it is invasive and so surface E/4 ismore commonly used# Signals from surface E/4electrodes are less reliable than signals from fine wireelectrodes because they can e perience interferencefrom neighboring muscles and they can slip or moveduring muscle actions, particularly where concentric oreccentric muscle actions are being performed <and notisometric muscle actions># &he electrophysiologicalsignal detected by electrodes starts when a musclefiber or group of muscle fibers is activated by thecentral nervous system <;"S> via a motor nerve# &heactivation starts with the electrophysiologicaldepolari ation cell membranes, leading to the releaseof ;a)F ions within the muscle cells, and thesubse$uent activation of actinQmyosin filaments toproduce a shortening of each sarcomere# &hus, E/4activity and mechanical force are closely related# Sincemechanical loading is thought to be the primary driverfor muscular hypertrophy, it is therefore unsurprisingthat e ercises that display high E/4 levels in certainmuscle groups are thought to be those that are mosteffective for developing those parts of the body#However, the interpretation of E/4 activity is not asimple matter and the signal re$uires processing and

normali ation before it can be properly compared withother signals# "ormali ation is most commonlyperformed relative to the signal recorded during ama imum voluntary isometric contraction in a positionthought to lead to the greatest possible E/4 activityof the muscle in $uestion# Such positions are notalways %nown for all muscles, however# 'dditionally,normali ation can also be performed relative to a non3ma imal, reference contraction# 'dditionally, thenature of the E/4 measurement ta%en can differbetween studies, depending on whether average E/4activity is ta%en across the whole of a given muscleaction, or whether the pea% E/4 activity during agiven muscle action is recorded#

*B+EC,I-E. &o investigate the effect of long3termstrength training on the relationship between muscleactivity and force production, by reference to theE/43moment relationship during both isometric %neefle ion and e tension muscle actions <measured whileseated in a chair with the feet on a force plate>, inboth resistance3trained male athletes and untrained

male participants#

P*P/0A,I*1. .( males, including untrainedsubjects <aged ).#9 L )#)9 years> and resistance3trained athletes <aged )=#- L 8#) years>#

What ha))ened3

;elationshi# between force and muscle activity &he researchers found a very strong, linear isometricE/43moment relationship for most muscles and jointactions in the strength3trained group# 2or e ample,the relationship between an%le plantar fle ion momentand gastrocnemius activity was e tremely strong <13s$uared G (#? >, as was the relationship between

%nee fle ion moment and biceps femoris activity <13s$uared G (#??># In contrast, the researchers foundthat the isometric E/43moment relationship wascurvilinear <$uadratic> for the untrained group#

)gonist antagonist co activation&he researchers found differences in the co3activationvalues between trained and untrained subjects, as wellas between the %nee e tension and %nee fle ionactions# &hey noted that co3activation was generallysignificantly greater in the untrained subjects than inthe trained subjects <-8 L 80 vs# =( L 80,respectively> and that it was significantly greater in%nee e tension than in %nee fle ion < ? L =0 vs# ==L 80, respectively#

What did the researchers conclude3&he researchers concluded that there is a linearrelationship between muscle activity <as measured byE/4> and joint moments in strength trained males butthat the E/43moment relationship was curvilinear<$uadratic> in untrained males# In addition, theyreported that co3activation values were much lower intrained subjects than in untrained subjects#

0imitations&he study was limited as it was cross3sectional andthe differences between subjects could have arisen

because of genetic factors leading the athletes tobecome athletes rather than the environmental factors<strength training over a long3term period>#


http://www.sciencedirect.com/science/article/pii/S105064111500070X

http://www.sciencedirect.com/science/article/pii/S105064111500070X

8/18/2019 SCR_MAY_15_PDF


0issociated time course of muscle damage recovery between single and multi !oint e"ercises in highly resistance trained men/ by 'oares/ 1erreira 3unior/Pereira/ Cleto/ Castanheira/ Cadore/ and %ottaro/ inThe 3ournal of 'trength Conditioning ;esearch4 -567 8

Background:elayed onset muscle soreness <:@/S> is fre$uentlye perienced by athletes and recreational traineeswhen e posed to either novel resistance3trainingwor%outs or a large volume of eccentric muscleactions# Symptoms include soreness, tenderness uponpalpation, and stiffness during movement# :@/Sappears to occur reliably between .) + )= hours post3wor%out, with soreness pea%ing around =9 hours post3wor%out# &here is a lac% of consensus regarding theunderlying mechanisms that cause :@/S# Someresearchers consider :@/S to be caused entirely bye ercise3induced muscle damage <EI/:># EI/: issimilarly characteri ed by muscle soreness, muscleswelling, an increase in intramuscular protein andpassive muscle tension, and also involves a reductionin muscular strength and range3of3motion# In thismodel, EI/: causes various disruptive changes,including sarcomere damage, calcium accumulation,protein degradation, and increased osmotic pressure#&hese changes lead to the sensiti ation of nociceptorsand other pain receptors, which leads to the sensationof :@/S being e perienced# ' number of differentinterventions have been tested for reducing both EI/:and :@/S# &here is some evidence to support the useof massage and limited evidence to support the use of self3myofascial release with a foam roller# &hemechanisms by which massage or self3massage mightbe effective for reducing :@/S are not well3understood and various possibilities are currentlybeing e plored by researchers# @ne interesting featureof :@/S is that it is dramatically reduced when themuscle has been e posed to a similar stimulus on arecent, previous occasion# &his is %nown as the

Arepeated bout effectB and indicates that centralfactors may well be involved in addition to local ones#

*B+EC,I-E. &o compare the effects of multi3 andsingle3joint e ercises on the speed of recovery frommuscle damage in resistance3trained males# 1ecoverywas measured indirectly through strength levels <byreference to ma imum voluntary isometric contraction</DI;> elbow fle ion tor$ue> and also through thesensation of :@/S by reference to a visual analog

scale, compared at baseline, .( minutes post3e erciseand after )=, =9, *) and ?- hours#

P*P/0A,I*1. .- resistance3trained males <aged)=# L # years> with C8 years of continuousstrength training e perience <mean G -#. L )#*years>#

I1,E -E1,I*1. 'll subjects performed 9 sets of .(1/ for a unilateral seated row e ercise with onearm and 9 sets of .(1/ unilateral biceps preacher curle ercise using the contralateral arm#

What ha))ened3

'trength recovery &he researchers found a significant decrease in /DI;elbow fle ion tor$ue .( minutes after both the multi3and single3joint e ercise sessions# However, thereduction decrease was significantly greater after thesingle3joint e ercise compared to after the multi3jointe ercise <)-#90 vs# . #.0># 'fter )= hours, /DI;elbow fle ion tor$ue was still lower in the single3jointcondition but returned to baseline in the multi3jointcondition#

09M' recovery &he researchers found a significant increase in :@/Sat )=, =9 and *) hours after the single3joint e ercise#:@/S returned to baseline at ?- hours# However, for

multi3joint e ercise, :@/S was significant increasedat )= and =9 hours and returned to baseline at *)hours# In addition, the severity of :@/S was greaterafter single3joint e ercise than after multi3jointe ercise at )=, =9 and *) hours post3e ercise#

What did the researchers conclude3&he researchers concluded that strength and musclesoreness recovery is dissimilar between single3jointand multi3joint e ercises in resistance3trained males#Strength and muscle soreness ta%e longer to recoverafter single3joint e ercises than after multi3jointe ercises#

0imitations&he study was limited as it is unclear whether thesame results would be observed with other muscles ore ercises#




8/18/2019 SCR_MAY_15_PDF


Muscle fascicle behavior during eccentric cycling and its relation to muscle soreness/ by Pe ailillo/ %lazevichand Nosa&a/ in Medicine 'cience in '#orts E"ercise 4 -567 8

Background

:elayed onset muscle soreness <:@/S> is fre$uentlye perienced by athletes and recreational traineeswhen e posed to either novel resistance3trainingwor%outs or a large volume of eccentric muscleactions# 2or an introduction to :@/S, see thepreceding study review#

*B+EC,I-E. &o compare the effects of unaccustomedand accustomed eccentric cycling on :@/S <byreference to the visual analog scale> and on strengthrecovery <as measured by reference to ma imalvoluntary isometric contraction </DI;> %nee e tensiontor$ue> in the =9 hours post3e ercise, and to e plorewhether any differences were associated with the

changes in muscle activity <as measured by electro3myography JE/4K> or changes in vastus lateralisfascicle length during e ercise <as measured usingultrasonography># E/4 activity was normali ed to/DI; levels#

P*P/0A,I*1. .. untrained males, aged )*#. L *#(years#

I1,E -E1,I*1. 'll subjects performed ) bouts of eccentric cycling <the first being unaccustomed andthe second being accustomed> separated by ) wee%s#Each bout of cycling was performed for .( min at - 0of ma imal concentric wor%load#

What ha))ened3

0ifferences in 09M' and strength recovery &he researchers found that :@/S was greater afterthe second <accustomed> bout of eccentric cycling#However, they noted that there were no differences instrength recovery between groups#

0ifferences in muscle activity &he researchers noted that muscle activity during thetwo bouts was not significantly different between thefirst <) #- L . # 0> and second bouts <)=#= L *#?0>#&his may suggest that the Arepeated bout effectB,which describes how one bout of eccentric e erciseprotects against soreness in a subse$uent bout, is not

caused by neural adaptations#

0ifferences in muscle fascicle length changes&he researchers noted that fascicle elongation was.-0 less in the first bout <unaccustomed> than in thesecond bout <-#* L 8#) vs# 9#( L )#-cm># &his maysuggest that the Arepeated bout effectB is caused byan alteration in fascicle strain# Since no change inoptimum length for tor$ue was observed <suggestingthat sarcomerogenesis did not occur>, this may implythat remodeling of muscle e tracellular matri too%place, increasing muscle stiffness#


&he researchers concluded that the Arepeated bouteffectB is not caused by neural adaptations but rathermight be caused by an alteration in fascicle strainsubse$uent to remodeling of the muscle e tracellularmatri , which in turn increases muscle stiffness#

0imitations&he study was limited in that the researchers did notdirectly assess whether any remodeling of thee tracellular matri in fact occurred between the twobouts of eccentric cycling#




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=erbal instructions acutely affect dro# vertical !um#biomechanics im#lications for athletic #erformanceand in!ury ris& assessments/ by *huu/ Musalem/ and %each/ in The 3ournal of 'trength Conditioning;esearch 4 -567 8

Background;oaching instructions can direct the focus of attentione ternally or internally# 'n e ternal focus is one thatdirects the athleteRs attention away from their bodyand towards the effects of their movement on theenvironment# @n the other hand, an internal focusdirects the athleteRs attention to their own bodymovements# Previous research into the area of attentional focus has found that an e ternal focus of attention is superior to either no focus of attention oran internal focus of attention for improving theobjective performance of the movement <i#e# greater

jumping distance or height, greater power output,etc#># &herefore, e ternal cues are thought to bebeneficial for improving athletic performance bothacutely and during a long3term training program,because of the greater loads or speeds involved# Incontrast, an internal focus has been found to lead toreductions in objective performance compared toeither an e ternal focus or no attentional focus butthey may simultaneously cause an increase in therecruitment of specific muscles# In this conte t, it isinteresting to note that bodybuilders have been usinginternal cues and internal focus with the Amind3muscleconnectionB for many years in order to enhancemuscular hypertrophy, which is believed to follow fromgreater muscle activity during a specific e ercise#

*B+EC,I-E. &o compare the effects of differentverbal instructions on vertical jump height, joint anglemovements, and ground reaction forces and poweroutputs during drop jumps#

P*P/0A,I*1. )( recreational athletes <.( males,aged )(#9 L .#= years .( females, aged )(#9 L )#(

years> from local volleyball, bas%etball, figure s%ating,and trac% and field teams#

I1,E -E1,I*1. &he athletes performed drop jumpsunder various conditions, which differed by the type of instruction that was given# &he 8 different instructionscomprised7 minimi e ground contact time, ma imi e

jump height, and synchronously e tend the lowere tremity joints#

What ha))ened3

0ifferences between verbal instructions&he researchers found that almost all measuredvariables were significantly between conditions, when

measured as a main effect# However, when comparingvariables between pairs of conditions, it was foundthat there were no differences between the latter twoconditions <ma imi e jump height vs# synchronouslye tend the lower e tremity joints>, which indicatedthat it was the first instruction <minimi e groundcontact time> that was responsible for causing thedifferences#

Effect of minimizing ground contact timeSpecifically analy ing the effects of the instruction

Aminimi e ground contact timeB, the researchers foundthat they landed more AstifflyB <i#e# performed lesssagittal plane trun%, hip, %nee, and an%le motion> andachieved lower ma imum jump heights#

What did the researchers conclude3&he researchers concluded that the precise nature of verbal instructions does affect joint angle movementsand performance during drop jumps# Specifically,instructing athletes to minimi e ground contact timeleads to stiffer landings and lower jump heights# Sincereduced sagittal plane joint angle ranges of motionduring jump landings have been lin%ed to increasedinjury ris%, this may imply that using this cue couldlead to adverse movement patterns being developedin athletes#

0imitations&he study was limited in that it was an acuteinvestigation and it is unclear what the long3termimplications of training with each of the various cuesmight be#


http://journals.lww.com/nsca-jscr/Abstract/publishahead/Verbal_Instructions_Acutely_Affect_Drop_Vertical.96972.aspx

http://journals.lww.com/nsca-jscr/Abstract/publishahead/Verbal_Instructions_Acutely_Affect_Drop_Vertical.96972.aspx

8/18/2019 SCR_MAY_15_PDF


0ifferences in end range of motion vertical !um#&inetic and &inematic strategies between trained weightlifters and elite short trac& s#eed s&aters/ by

aug/ '#ratford/ Gilliams/ Cha#man/ 0rin&water/aug/ ,everrier 'treet/ in The 3ournal of 'trength

Conditioning ;esearch 4 -567 8

BackgroundDertical jumping ability is a %ey athletic $uality# &hus,researchers have assessed both the biomechanics of vertical jumping and also the transfer of training tovertical jumping performance from several types of commonly3used training methods# Studies havereported beneficial effects on vertical jump heightfrom several training methods, including unilateralplyometrics, bilateral plyometrics, loaded jumps,unilateral conventional strength training, conventionalstrength andQor power training, isometric strengthtraining, @lympic lifting programs, %ettlebell training,comple and contrast training, assisted and resisted

jumps, and multiple combined methods# Studiese ploring the biomechanics of vertical jumping haveattempted to identify the %ey factors that contribute toincreased jumping performance# In this respect,previous studies have identified that co3ordination,strength, rate of force development and elastic energystorage through the stretch3shortening cycle can allinfluence vertical jump performance to some degree#Since vertical jumping ability is a %ey athletic $ualityli%e hori ontal jumping ability, sprint running abilityand agility, a number of studies have assessed thecorrelations between each of these different $ualities,with varying results, although generally with positivecorrelations in all cases#

*B+EC,I-E. &o identify whether there are anydifferences in jumping movement patterns <asmeasured by the joint angle movements trac%edthrough a . camera motion analysis system lin%ed toa force plate> between resistance3trained and vertical

jump3trained athletes and controls#

P*P/0A,I*1. . subjects, including = weightlifters<aged )*#) L =#- years>, short trac% speed s%aters<aged .?#( L )#= years>, and - untrained controls<aged ) #( L )#. years>#

I1,E -E1,I*1. Subjects performed - s$uat jumpsand - countermovement jumps with no e ternal load#

What ha))ened3

'(uat !um#2or the s$uat jump, the researchers found a largedifference between the weightlifters and the shorttrac% speed s%aters in respect of the time before toe3off of pea% vertical velocity# &hey also found a large

difference between the same groups for the decreasebetween pea% and toe3off vertical velocity#

Countermovement !um#2or the countermovement jump, the researchersfound a large difference between the weightlifters andthe short trac% speed s%aters in respect of the timebefore toe3off of pea% vertical velocity and for thedecrease between pea% and toe3off vertical velocity#

What did the researchers conclude3&he researchers concluded that @lympic weightliftersdisplay different jumping movement patterns fromshort trac% speed s%aters even though both groupsare resistance3trained#

0imitations&he study was limited in that it is not completely clearwhether the strategies adopted by the weightlifterswere superior to those adopted by the short trac%speed s%aters or whether they were a function of thetypes of movements that the athletes had performedin the past#


http://pdfs.journals.lww.com/nsca-jscr/9000/00000/Differences_in_End_Range_of_Motion_Vertical_Jump.97010.pdf

http://pdfs.journals.lww.com/nsca-jscr/9000/00000/Differences_in_End_Range_of_Motion_Vertical_Jump.97010.pdf

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,% ANATOMY' PHYSIO+OGY' AND NUTRITION


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E"tracellular matri" remodeling and its contribution to #rote c t iv e ada#t at io n fol lowing lengt hen ingcontractions in human muscle/ by yldahl/ Nelson/Gelling/ +roscost/ ubal/ and Parcell/ in The 1)'E%

3ournal 4 -567 8

BackgroundWhile the focus of research into muscle adaptationsfollowing resistance training has been primarily onincreases in muscle si e <hypertrophy> and secondlyon changes in muscle architecture, such as increasesin fiber length or pennation angle, other adaptations inmuscles do occur# Indeed, although changes in specifictension are thought to account for a large proportionof the difference between gains in strength and si efollowing a long3term resistance training program, theunderlying causes for these increases in specifictension are not well3understood# It is thought thatincreases in specific tension are partly caused byincreases in myofibrillar pac%ing density <which isindicated by the ratio of strength3to3si e in a single invitro muscle fiber> and partly by shifts in the degree towhich e tracellular lateral force transmission occurs,which is believed to occur through sarcomeresattaching to the e tracellular matri # &he e tracellularmatri is the structure that connects individual musclefibers to allow force transmission within the wholemuscle# Signaling within the &423 superfamilypathway appears to be important for activating theproteolytic systems within muscle fibers and forregulating the synthesis and remodeling of thee tracellular matri after it has been damaged,particularly subse$uent to eccentric e ercise# Whenthe e tracellular matri is damaged, this allows aninflu of calcium ions, which activates proteases thatproteolyse titin and dismantle the damaged chains of sarcomeres# &his process also liberates myostatinbound at the sarcomere, which conse$uently becomesfree to participate in signaling cascades# /yostatinmay then bind to its receptors and bring aboutnecessary proteolysis within muscle fibers, which isimportant for recycling e isting damaged proteinsfollowing damage caused during resistance traininge ercise#

*B+EC,I-E. &o assess whether e tracellular matriremodeling contributes to the repeated bout effectduring eccentric training by ta%ing muscle biopsies 8hours, ) days, and )* days after an initial bout of eccentric training and ) days after a repeated bout, inorder to assess differences in the elevation of e tracellular matri structural, matricellular and

molecular signaling transcripts#

P*P/0A,I*1. .= healthy, untrained adult subjects<* males, aged )8#8 L )#. years * females, aged) #- L )# years>#

I1,E -E1,I*1. 'll subjects performed ) bouts of eccentric training for the %nee e tensors, separated by)9 days# Each bout comprised 8( sets of .( ma imaliso%inetic eccentric %nee e tension muscle actionsthrough a range of motion between 8( + ..( degreesof %nee angle at .)( degreesQs, with . minute restbetween sets#

What ha))ened3

)cute measures of e"tracellular matri" remodeling&he researchers found that in an acute e ploration of the molecular responses to eccentric training, thehighest responding transcripts in the networ% werethose that encoded for proteins with %nown functionsof de3adhesion <including tenascin ; <&";>, whichincreased ..#- times> and transcriptional regulationand signaling, including connective tissue growthfactor <;&42>, which increased *#- times, andtransforming growth factor3 ) <&423 )>, whichincreased *#9 times#

;e#eated bout effect &he researchers found that &"; activity increased

significantly after the first bout but not after thesecond bout# 'lso, the activity of this mar%er of e tracellular remodeling was positively correlated withthe reduction in strength post3e ercise <13s$uared G(#= ># &"; facilitates cell de3adhesion, which reducesthe strength of the connections between the e tra3cellular matri and the integrins that connect it to thecell membrane, which permits remodeling#

What did the researchers conclude3&he researchers concluded that e tracellular matriremodeling does appear to be associated with therepeated bout effect#

0imitations&he study was limited in that it is unclear preciselywhat remodeling of the e tracellular matri is beingunderta%en and what the implications of this processare for long3term strength gains#


http://www.fasebj.org/content/early/2015/03/25/fj.14-266668.abstract

http://www.fasebj.org/content/early/2015/03/25/fj.14-266668.abstract

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Is it time to turn our attention toward central mechanisms for #ost e"ertional recovery strategiesand #erformance$ %y ;attray/ )rgus/ Martin/ Northey/and 0riller/ in 1rontiers in Physiology 4 -567 8

*B+EC,I-E. &o discuss how certain recovery

strategies might be used to reduce mental fatigue andthereby offer an opportunity for improving repeatedperformance#

,he evie4

Introduction&he reviewers observe that traditionally, discussion of post3e ercise recovery has almost e clusively focusedon combatting peripheral fatigue# However, researchhas demonstrated that central fatigue also occurs#&herefore, it is possible that strategies might beadopted to address central fatigue specifically andthereby enhance overall performance recovery#/oreover, they observe that it is possible that many of the strategies that have been devised in order toassist with peripheral recovery may also e ert theireffects via central mechanisms#

Nutritional strategies&he reviewers note that it has long been well3%nownthat carbohydrate is effective for enhancing recoverywhen consumed post3e ercise# However, it has onlymore recently been observed that mouth3rinsing withcarbohydrate also has a beneficial <and immediate>effect on reducing fatigue# Interestingly, they alsonote that this occurs before the elevation of bloodglucose# &o e plain this phenomenon, it has beensuggested that carbohydrate acts by influencing

neurotransmitter precursors <such as tryptophan> thatcross the blood3brain barrier and elevate levels of neurotransmitters <such as serotonin># It has in factbeen observed that carbohydrate reduces the amountof tryptophan crossing the blood3brain barrier duringe ercise, which could feasibly therefore alter serotoninlevels, which have been found to impact on mood andsleepiness# In addition to carbohydrate, the reviewersnote that it is also well3%nown that the ingestion of protein post3e ercise is beneficial for recovery# 'gain,they note that there are reasons to believe that theremay be some central mechanisms involved in thisprocess of recovery# Specifically, since branched chainamino acids are carried by the same system astryptophan, the consumption of protein is thought tobe able to modulate levels of this %ey neuro3transmitter precursor and thereby act in order to alterserotonin levels#

Mental fatigue&he reviewers note that the concept of enhancingrecovery from mental fatigue has rarely been e ploredin either research or practice# /ental fatigue can occuras a result of any cognitive tas% and results in achange in psychological state that impacts on theability to perform in future tas%s and causes adversechanges in mood and feelings of tiredness# @f greatimportance are recent studies showing that mentalfatigue generated through the performance of purely

cognitive tas%s can lead to reduced performance inphysical endurance tas%s, such as %m running timetrials# Such trials typically report that the rating of perceived e ertion <1PE> is greater following thecondition performed after the mentally3fatiguing tas%#Investigations in this area have suggested thatalterations in the anterior cingulate corte may occur

subse$uent to cognitive effort# &he anterior cingulatecorte is an area of the prefrontal corte that is highlyactivated by cognitive effort# 1esearchers wor%ing inthis new field have suggested a model in which fatigueduring endurance performance is affected by thebalance of two competing psychological factors7perceived e ertion and potential motivation# &hus,factors that either increase the rating of perceivede ertion or increase the benefits associated withsuccess might be e pected to reduce or increase theeffects of fatigue, respectively# Indeed, motivationalself3tal% and the presence of an attractive audienceduring testing have both been found to increaseendurance performance#

What did the revie4ers conclude3&he reviewers concluded that many post3e ercisestrategies that are intended to enhance peripheralrecovery may also improve central recovery throughdifferent mechanisms# However, they note that theremay also be other interventions that could beperformed in order to enhance central recovery thathave not yet been e plored# 2urther research shouldbe performed in this area#

0imitations&he narrative review was performed by one group of researchers who may not share the opinions of all of the researchers wor%ing in this field# In addition, therehas been limited research performed assessing thecentral mechanisms of recovery from strenuous andfatiguing e ercise#




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0oes regular #ost e"ercise cold a##lication attenuatetrained muscle ada#tation$ %y Jamane/ 9hnishi/ and Matsumoto/ in International 3ournal of '#ortsMedicine 4 -567 8

Background

1ecovery from training and competition is veryimportant for athletes# Mntil they are fully recovered,athletes cannot function again at their previous highlevel of performance# However, recovery is difficult todefine precisely# It is often defined as the rate atwhich the fatigue induced by a prior training bout orcompetition is dispersed, relative to the magnitude of that fatigue# ut since fatigue is also difficult to pindown and measure precisely, even this broaddefinition is problematic# 'dditionally, recovery is oftenmeasured over multiple different time periods# Ingeneral, there are three main types of recoveryreferred to in the literature7 immediate recovery,short3term recovery, and training recovery# Immediaterecovery refers to the recovery that is allowed duringperformance, between muscular contractions# 2ore ample, a certain amount of recovery for the legmuscles occurs during the flight phase of runningbetween ground contact phases# Short3term recoveryoccurs between sets of intervals or between multiplesets of resistance3training e ercises# &raining recoveryrefers to the period of adaptation between se$uentialwor%outs or between competitions# &he definition of the time periods still does not address the problem of what is being measured, however# &herefore, in orderto bring some measure of precision to the study of recovery, researchers have settled on various indirectmeasures of recovery, including glycogen re3synthesis,electrolyte replacement and rehydration, performancemeasures <e#g# ma imal strength, repetition strength,muscular power or anaerobic power output>,biomar%ers of muscle damage such as creatine %inase<;N>, changes in heart rate variability <H1D>, and self3perception of delayed onset muscle soreness <:@/S>#&he individual performance measures are clearly ableto provide a concrete understanding of how muchfatigue has affected the athlete and how long suchperformance too% to return# However, the e act speedat which performance returns is affected by anysuper3compensation that might occur in response tothe training bout# &he biomar%ers of muscle damagecan appear to be slightly more AscientificB measures tosome people, as can H1D measurements# However,

the e tent to which these measures <and others> aregood measures of overall fatigue is open to debate# 'number of different interventions have been tested forreducing improving recovery and reducing :@/S#&here is some evidence to support the use of massageand limited evidence to support the use of self3myofascial release with a foam roller for reducing:@/S, in particular# However, the mechanisms bywhich such modalities might be effective for reducing:@/S are not well3understood#

*B+EC,I-E. &o assess the effects of regular post3e ercise cold application on gains in muscular si e <byreference to wrist3fle or thic%ness using 3modeultrasound> and strength <by reference to ma imalisometric wrist fle ion force> as a result of a long3termresistance training program#

P*P/0A,I*1. .= recreationally active male subjectsaged )(#) L (#? years, randomly allocated into eithera cold application group <* subjects> or a controlgroup <* subjects>#

I1,E -E1,I*1. 'll subjects participated in aresistance training program of sets of 9 machine3based wrist3fle ion e ercises at *(+9(0 of .1/, 8times a wee% for - wee%s# &he cold application groupimmersed their forearms in cold water <.( L .degrees ;> using constant temperature water bathunit for )( minutes post3e ercise# &he control groupdid not e perience cold application post3e ercise#

What ha))ened3

Muscular strength&he researchers found that ma imal isometric wrist3fle ion force increased significantly only in the controlgroup and not in the cold application group#

Muscular size&he researchers found that wrist3fle ion thic%nessincreased significantly in both groups but the controlgroup increased significantly more than the non3cooled group#

What did the researchers conclude3&he researchers concluded that performing regularpost3e ercise cold application to e ercised musclesappears to attenuate adaptations to long3termresistance training#

0imitations&he study was limited in that only one small musclegroup was tested and in that it was performed only inuntrained subjects# :ifferent results might beobserved in other populations or in other muscles#




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Mental fatigue does not affect ma"imal anaerobic e"ercise #erformance/ by Martin/ Thom#son/ *eegan/%all/ and ;attray/ in Euro#ean 3ournal of )##lied Physiology 4 -56K 8

Background

;onventionally, muscular fatigue is subdivided intotwo aspects, central and peripheral# ;entral fatiguerefers to processes that occur pro imally to theneuromuscular junction, while peripheral fatigue refersto processes that occur distally to the neuromuscular

junction# It is most straightforward to thin% of centralfatigue as occurring spinally or supra3spinally andperipheral fatigue as occurring within the muscle itself#In order to investigate these two different types of fatigue, researchers have developed a range of tools#;entral fatigue is commonly e plored using the twitchinterpolation techni$ue, which involves evo%ingmuscular twitches through electrical stimulation duringma imal voluntary contractions </D;s># However,there are various other methods that can be used toe plore both central and peripheral fatigue#&ranscranial magnetic stimulation <&/S> is a methodthat is often used, and allows researchers to measurecorticospinal e citability with motor evo%ed potentials</EPs> and also the superimposed twitch responses#In general, previous studies have found that the si eof /EPs increases as a result of e ercise3inducedmuscle fatigue# However, not all studies have foundthis same result# &he central activation ratio <;'1>and evo%ed pea% twitch force <P&2> can also separateout the central fatigue <i#e# motor neuron firing> andperipheral fatigue <e#g# e citation3contractioncoupling> elements of overall fatigue# P&2 is typicallycalculated as the pea% change in force duringpassively stimulated muscular contractions <i#e# themuscle is rela ed prior to the electrical stimulus> fromthe pre3stimulated values recorded in a dynamometer#;'1 is typically calculated in a similar way but isdifferent in two %ey respects# 2irstly, the electricalstimulation of the muscle is performed while themuscle is contracting and not rela ed# Secondly, it iscalculated as the ratio of pea% voluntary force <prior tothe stimulation> to the pea% electrically stimulatedforce and not as the change# &hese measurements areuseful in this conte t, as it is possible that heavy,moderate and light loads lifted with ma imal velocitycould lead to different components of overall fatigueand therefore give rise to differing responses#

*B+EC,I-E. &o assess the effects of mental fatigueon tests of athletic performance <by reference tocountermovement jump height assessed by a linearposition transducer>, muscular strength <by referenceto ma imum isometric %nee e tension tor$ue> andanaerobic capacity <by reference to a 83minute all3outcycling test># In addition, psychological variables were

assessed, including mood <by reference to the P@/Sinventory> and rating of perceived e ertion <1PE>#

P*P/0A,I*1. .) athletically3trained subjects <*males and females>, aged )8 L 8 years#

I1,E -E1,I*1. 'll subjects were tested after eithera mentally fatiguing tas%, comprising ?( minutes of the computer3based ;ontinuous Performance &as% orafter a control treatment involving ?( minutes of watching emotionally neutral documentaries#

What ha))ened3

Performance variables

&he researchers found no difference between the twoconditions in respect of athletic performance, muscularstrength or anaerobic capacity tests#

Psychological variables'lthough there was no difference in any of theperformance variables, the researchers did note that1PE was non3significantly higher in the mentallyfatigued condition compared to the control <.? L . vs#.9 L .># &hey also noted that intrinsic motivation wasnon3significantly lower in the mentally fatiguedcondition <.. L = vs# .8 L -># Whether these findingsare meaningful is unclear as the results were notsignificant#

What did the researchers conclude3&he researchers concluded that since there were noeffects of mental fatigue on any of the athleticperformance, muscular strength or anaerobic capacitytests, this implies that peripheral mechanisms areprimarily responsible for the regulation of ma imalanaerobic e ercise#

0imitations&he study was limited in that it is unclear whethersimilar results would be observed in subjects whowere trained to perform jumping activities or whowere accustomed to high3intensity short3durationefforts in a competitive environment, such as trac%cycling#


http://link.springer.com/article/10.1007/s00421-014-3052-1

http://link.springer.com/article/10.1007/s00421-014-3052-1

8/18/2019 SCR_MAY_15_PDF


igh #rotein/ low fat/ short term diet results in lessstress and fatigue than moderate #rotein/ moderatefat diet during weight loss in male weightlifters: a #ilot study/ by elms/ Ainn/ ;owlands/ Naidoo/ and Cronin/in International 3ournal of '#ort nutrition and E"erciseMetabolism 4 -56K 8

Background&he global consumer mar%et for dietary supplementsin )(.. was estimated at TU8( billion# Proteinsupplements are among the most popular itemspurchased# Protein supplements are available in bothli$uid and solid forms, although the li$uid form is themost common# 'dditionally, while various types of protein are available, whey is the most commonlyused in commercially3available supplement formulas#Protein supplements are primarily intended to increasemuscular strength and si e when consumed incombination with periods of resistance3training,largely by increasing total daily protein inta%e#1esearch indicates that consuming a proteinsupplement may increase total protein inta%e butother dietary factors may be modifying factors,including whether individuals are engaged in caloricrestriction or not# "evertheless, a substantial body of acute research has found that dietary proteinconsumption immediately post3resistance3traininge ercise leads to an increase in muscle proteinsynthesis and a reduction in muscle proteinbrea%down# Increases or decreases in muscular si e<hypertrophy or atrophy> are thought to occur througha sustained imbalance between muscle proteinsynthesis and muscle protein brea%down# Sinceincreases in muscle protein synthesis are believed tobe important contributors to long3term gains in musclemass, this is often ta%en as evidence that proteinsupplementation can be used to enhance gains inmuscular strength and si e# However, not all long3term trials have supported this claim and we shouldbe cautious about drawing strong inferences abouthypertrophy from the behavior of muscle proteinsynthesis and the balance between muscle proteinsynthesis and muscle protein brea%down in acutetrials, as some studies have found no correlationbetween these acute responses and long3term gains inmuscle mass# It is fortunate that meta3analyses of trials of resistance3training programs of C- wee%shave reported that protein supplementation does leadto superior gains in strength and si e in both young

and old adult subjects# Protein supplementation maybe provided from several different sources and someresearchers have suggested that the use of eitherwhey, casein or essential amino acids may lead todifferent effects, most li%ely by altering the rate of muscle protein synthesis or muscle protein brea%downpost3e ercise# Indeed, essential amino acids such asthe branched3chain amino acids < ;''> can increasemuscle protein synthesis and reduce muscle proteinbrea%down# 'dditionally, the essential amino acidleucine could be an important modulator insofar as itseems to lead to an increase in the activity of important signaling proteins#

*B+EC,I-E. &o compare the effects of two differentcarbohydrate3matched diets <high3protein and low3fatvs# moderate3protein and moderate3fat> on changes inanthropometrics and muscular strength <by referenceto isometric mid3thigh pull># 'lso, the researchersmeasured changes in mood <by reference to theProfile of /ood States <P@/S> inventory and stress

<by reference to &he :aily 'nalysis of 6ife :emands of 'thletes <:'6:'> score>#

P*P/0A,I*1. .= resistance3trained males, aged )(+ =8 years, randomly allocated into either a high3protein and low3fat group or a moderate3protein andmoderate3fat group# &he groups were tested in arandomi ed, cross3over design#

I1,E -E1,I*1. 'll subjects performed resistance3training for ) days per wee% during the ) wee%s of thestudy# Each group followed a carbohydrate3matcheddiet# &he high3protein low3fat group consumed )#9gper %g of bodyweight of protein per day <with fataccounting for . #=0 of total calories> while the

moderate3protein moderate3fat group consumed just.#-g per %g of bodyweight of protein per day <with fataccounting for 8-# 0 of calories># &he groups wereblinded by providing meal plans and ma%ing up thedifference in macronutrient re$uirements through theuse of protein supplement powders#

What ha))ened3

Muscular strength and anthro#ometrics&he researchers reported that changes in muscularstrength anthropometrics were li%ely trivial#

Psychological variables&he researchers reported that there were li%ely larger,

adverse changes on the :'6:' test items for themoderate3protein moderate3fat group than for thehigh3protein low3fat group# &he :'6:' predominantlyassesses elements of stress# Similarly, they reportedli%ely or possibly larger adverse changes on the P@/Stest items for the moderate3protein moderate3fatgroup than for the high3protein low3fat group# &heP@/S predominantly assesses elements of fatigue andmood disturbance#

What did the researchers conclude3&he researchers concluded that measures of stressand fatigue were higher during a moderate3proteinmoderate3fat diet than during a high3protein low3fat

diet#

0imitations&he study was limited by the short duration of thediets and different results might be observed if thediets had been conducted for longer periods of time#




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Inde#endent effects of endurance training and weight loss on #ea& fat o"idation in moderately overweight men: a randomized controlled trial/ by Nordby/;osen&ilde/ Ploug/ Gesth/ 1eigh/ Nielsen/ and 'tall&necht/ in 3ournal of )##lied Physiology 4 -567 8

Background@besity and overweight are rapidly rising phenomenaworldwide and are both important contributors tomortality and ill health# Weight loss is the primarytechni$ue for addressing both of these conditions#Weight loss is essentially achieved by means of altering the balance between the amount of caloriesconsumed and e pended# 't its most basic, therefore,weight loss can be achieved either by reducingcalories consumed, increasing calories e pended, or acombination of both# However, there are many ways inwhich calorie inta%e can be increased and in whichcalorie e penditure can be increased# ;alorie inta%ecan be reduced directly by conscious dietarymodifications or indirectly by bariatric surgery,pharmacology, and even psychological protocols#;onscious dietary modifications can themselves befurther subdivided into either <.> a reduction in foodvolume without changes in macronutrient ratios orfood choices or <)> a change in dietary patterns toalter either macronutrient ratios or food choices#;alorie e penditure can be increased either byphysical activity or by specific e ercise protocols# &hemajority of individuals in the general populationappear to instinctively identify diet as the primary wayto lose weight although many also include e ercise asan adjunct# However, there are widely varyingopinions regarding the optimal ways to lose weightand e perts have made recommendations regardingthe optimal macronutrient ratios, food choices,e ercise protocols <i#e# aerobic steady state vs#anaerobic intervals vs# resistance training, etc#> andtarget rate of weight loss to achieve over a set periodof time# &he e tent to which these recommendationshave been supported by long3term trials, however, isunclear# In addition, the e tent to which differenttypes of weight loss intervention lead to differentresults in males and females is also currentlyun%nown#

*B+EC,I-E. &o compare the effects of endurancetraining <with or without weight loss> with diet3inducedweight loss on pea% fat o idation <as measured bystandard stoichiometric e$uations for respiratorygaseous e change during sub3ma imal e ercise tests>and s%eletal muscle mitochondrial proteins involved infat o idation <by ta%ing muscle biopsies from the

vastus lateralis>#

P*P/0A,I*1. -( moderately overweight, sedentarymales, randomly allocated to either endurance trainingwith weight loss, endurance training without weightloss <through increased caloric inta%e>, diet, or non3training or diet control groups#

I1,E -E1,I*1. 'll subjects performed .) wee%s of endurance training, diet, or no activity, depending ontheir group#

What ha))ened3

Geight loss

&he researchers observed a similar weight loss in theendurance training with weight loss <3 #? L (#*%g>and diet <3 #) L (#9%g> groups while endurancetraining without weight loss <3.#( L (# %g> and control<F(#. L (#-%g> groups did not lose weight#

Pea& fat o"idation&he researchers found pea% fat o idation increased toa similar e tent in the endurance without weight lossgroup and the endurance with weight loss groups<=.0 vs# =)0> compared to the control group#However, pea% fat o idation did not increase in thediet group#

What did the researchers conclude3&he researchers concluded that endurance trainingincreases pea% fat o idation in moderately overweightmales, irrespective of weight loss# Since a high level of pea% fat o idation during e ercise is associated with ametabolically healthy phenotype, this may underpinsome of the health benefits of e ercise over and aboveweight loss for the treatment of obesity#

0imitations&he study was limited in that it is unclear whetheraltering pea% fat o idation levels in sedentary maleshas any specific long3term health benefits#


http://jap.physiology.org/content/early/2015/01/20/japplphysiol.00715.2014.abstract

http://jap.physiology.org/content/early/2015/01/20/japplphysiol.00715.2014.abstract

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The im#act of neuromuscular electrical stimulation onrecovery after intensive/ muscle damaging/ ma"imal s#eed training in #rofessional team s#orts #layers/ by Taylor/ Gest/ owatson/ 3ones/ %rac&en/ ,ove/ and *ilduff/ in 3ournal of 'cience and Medicine in '#ort 4 -56K 8

Background"euromuscular electrical stimulation <"/ES> traininghas previously been proposed as a tool to help reducelosses in muscle mass during periods of limbimmobili ation# "/ES involves the invo%ing of involuntary, isometric contractions of specific musclegroups at a relatively low intensity# &his techni$ue canbe used even in the injured limb under certaincircumstances# 1esearchers have found that by usinga relatively high fre$uency <.((H > and pulse width<=((5s> the otherwise significant muscle atrophy thatoccurs in the first days of limb immobili ation can beavoided or at least reduced by means of using twice3daily, 8(3minute sessions of "/ES# 'dditionally,studies have reported that muscular strength can beimproved using "/ES during periods of rehabilitationeven where limbs are not immobili ed, such asfollowing surgery for an injury# While "/ES isgenerally performed in conjunction with isometricmuscle actions, it is also possible to use it incombination with either concentric or eccentric muscleactions, which may be more beneficial for improvingfull joint range3of3motion strength measures#

*B+EC,I-E. &o assess the effects of "/ES on )=3hour recovery <as measured by countermovement

jump height, perceived muscle soreness, blood lactateand creatine %inase levels, and salivary testosteroneand cortisol levels> post3e ercise in professional soccerand rugby players#

P*P/0A,I*1. )9 male professional rugby and socceracademy players, aged )( L = years#

I1,E -E1,I*1. 'll subjects completed - V (mma imal sprints, with minutes rest between sprints#'fter one sprint session, the subjects wore a "/ESdevice for 9 hours post3e ercise over the peronealnerve behind the %nee, delivering an electrical currentof )*m' at a fre$uency of .H , with a pulse width of .=( 5s# &he researchers noted that this settingproduced visible contractions in the calf muscle but didnot cause discomfort#

What ha))ened3&he researchers found that countermovement jumpheight was reduced by significantly less in the "/EScondition than in the control condition <X8#) L 8#) vs#X*#) L 8#*0>, creatine %inase concentrations wereelevated by significantly less in the "/ES conditionthan in the control condition, perceived soreness waselevated by significantly less in the "/ES conditionthan in the control condition, and there was nodifference between conditions in respect of eitherblood lactate or salivary testosterone and cortisolresponses#

What did the researchers conclude3&he researchers concluded that "/ES can be used toimprove )=3hour recovery in soccer players, asmeasured by reference to countermovement jumpheight ability, creatine %inase levels, and perceivedsoreness#

0imitations&he study was limited as it is unclear by whatmechanism the improved recovery was effected#2uture research might benefit from using some meansof sham treatment to assess whether there is aplacebo effect in operation#




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The im#act of high intensity interval training versusmoderate intensity continuous training on vascular function: a systematic review and meta analysis/ by ;amos/ 0allec&/ T!onna/ %eetham/ and Coombes in'#orts Medicine 4 -567 8

BackgroundInterval training was first developed by trac% and fieldathletes in the middle of the last century to helpimprove middle3 and long3distance runningperformance# &rac% running performance, li%eperformance in other endurance sports, is dependentupon three main physiological factors7 aerobiccapacity, lactate threshold, and wor% economy#&ogether, these variables can e plain the largemajority of the difference in endurance performancebetween individuals in both heterogenous <varied> andhomogenous <similar> groups# In contrast, each of thevariables alone is only able to e plain the majority of the difference in endurance performance between theindividuals in heterogenous groups# 'erobic capacity ismeasured using D@)3ma , which is the volume of o ygen that the body can ta%e in and use effectively ina given period of time, usually measured relative tobodyweight as mlQ%gQmin# 6actate threshold ismeasured by reference to blood lactate# :uring anincremental e ercise test, blood lactate initiallyremains close to its resting value# 't a certain e erciseintensity, however, it rises above the resting value andthis e ercise intensity is called the lactate threshold#1unning economy <strictly wor% economy if includingother e ercise modalities> is a measurement of theefficiency of the athlete# Economy is most commonlydescribed in terms of how much o ygen it ta%es to runa given distance at a given speed# &raditionally, thee clusive method for developing enduranceperformance was steady3state e ercise# Indeed,researchers have found that steady3state e ercise canimprove endurance performance in untrainedindividuals# However, improvements in already well3trained individuals are small# ;onse$uently, studiese ploring the effects of steady3state e ercise intrained subjects have often failed to find significantincreases in endurance performance or in any of theunderlying physiological factors <aerobic capacity,lactate threshold, and wor% economy># /ore recently,high3intensity interval training <HII&> has beendeveloped as a tool for increasing enduranceperformance# HII& can be broadly defined as repeated

bouts of short3to3moderate duration e ercise <i#e# .(seconds to minutes> at an intensity greater than theanaerobic threshold# &hese e ercise bouts are dividedby short bouts of either low3intensity wor% orinactivity that allow either a partial or a full recovery#1esearchers have found that HII& can improveendurance performance in untrained individuals# &heincreases are often larger than those following fromsteady3state interventions of similar duration#/oreover, research has often found significantincreases in endurance performance in trainedindividuals following HII& e ercise interventions#

*B+EC,I-E. &o perform a systematic review andmeta3analysis of the literature comparing the effectsof HII& with moderate3intensity continuous training</I;&> on vascular adaptations <as measured byreference to brachial artery flow3mediated dilation>#'rtery flow3mediated dilation is a pro y measure for atrue vascular function measure, which is the ability of

the endothelial and smooth muscle cells to rela inresponse to a stimulus#

S,/56 SE0EC,I*1. 'll randomi ed trials <controlledor not controlled> comparing the effect of HII& and/I;& e ercise protocols on vascular function, asmeasured by brachial artery flow3mediated dilation,with program durations of C) wee%s#

What ha))ened3

'tudy selection&he researchers identified * randomi ed trials, whichinvolved a total of .9) patients#

=ascular function&he researchers reported that their meta3analysisfound brachial artery flow3mediated dilation improvedsignificantly by =#80 and )#)0 after HII& and /I;&,respectively# &he HII& programs were significantlymore beneficial than the /I;& programs# &o e plainthese differences, the reviewers proposed that sinceHII& includes rest periods, this might reduce some of the adverse effects on the vasculature that may occurfollowing continuous e ercise training while retainingthe beneficial effects of the e ercise#

What did the researchers conclude3&he researchers concluded that HII& is more effective

than /I;& for improving vascular function, asmeasured by brachial artery flow3mediated dilation#

0imitations&he study was limited in that it is unclear whetherreducing measures of brachial artery flow3mediateddilation lead to meaningful changes in health statusover long3term periods of time#


http://link.springer.com/article/10.1007/s40279-015-0321-z

http://link.springer.com/article/10.1007/s40279-015-0321-z

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-% PHYSICA+ THERAPY AND REHA*I+ITATION


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The #reventive effect of the Nordic hamstring e"erciseon hamstring in!uries in amateur soccer #layers arandomized controlled trial/ =an der orst/ 'mits/Petersen/ +oedhart/ and %ac&"/ in In!ury Prevention4 -56K 8

BackgroundHamstring strains are a common injury in manypopular team sports and they lead to the loss of manyhours of training and competition, as well as a veryhigh re3injury rate# Hamstring strains account for .) +.-0 of all injuries in athletes across a range of popular team sports, including rugby, soccer, 'merican2ootball, and 'ustralian 1ules 2ootball# &he re3injuryrate for hamstring strains ranges from .- + 8=0,depending upon the sport# 1unning activities accountfor most hamstring strains, with * + -90 of strainsoccurring during running# &he traditional model forhamstring strain injury is that there are variousfactors that could cause an injury to occur, including7fle ibility, strength, fatigue, core stability, musclearchitecture, and damage resulting from previousinjury# ' modern, more sophisticated approach hassuggested that while these factors could individuallylead to an injury, it is more li%ely that they interactwith each other in order to create multi3factorialscenarios that raise injury ris%# Some researchershave suggested that there are at least two differenttypes of hamstring strain injury7 those caused bystretching activities and those caused by high3speedrunning movements# &he hamstring strain injurycaused by high3speed running is thought to occurmost normally in the long head of biceps femoris,typically involves the pro imal muscle3tendon

junction, displays a greater reduction in strengthfollowing injury than those following stretchingmovements, and leads to a relatively long recoverytime to reach pre3injury levels of performance <e#g#around ( wee%s># &he biceps femoris <long head> isgenerally thought to be the most commonly3injuredhamstring muscle, although some researchers havesuggested that this perception might be incorrectbecause of inherent errors in common diagnosticapproaches# iomechanically, however, there are goodreasons for assuming that the biceps femoris might bemost at ris%# 2irstly, this muscle increases in length bymore than the other hamstring muscles duringsprinting# Secondly, the moment arm lengths of thebiceps femoris in the sagittal plane increase in the late

swing position compared to the anatomical position#Previous research has identified that hamstring strainsoccur most fre$uently either in the late swing or earlystance phases of gait# 6ate swing involves the greateststrain in the muscle, while early stance involves thelargest joint moments# &here is good evidence tosuggest that hamstring strain injuries can be reducedby eccentric hamstring training but not by fle ibilitytraining alone# &his has encouraged many strengthcoaches to incorporate the "ordic hamstring curl intohamstring strain prevention programs# However, thereis only limited evidence to suggest that hamstringwea%ness predicts strain injury ris%#

*B+EC,I-E. &o assess whether the "ordic hamstringcurl can reduce the incidence and severity of hamstring injuries in male amateur soccer players#

P*P/0A,I*1. /ale amateur soccer players, aged)=# L 8#9 years, from =( teams, randomly allocatedinto either a "ordic hamstring curl group <)( teams,

)?) players> or a non3training control group <)(teams, )9* players>#

I1,E -E1,I*1. &he "ordic hamstring curl groupperformed ) sessions of a wor%out involving the"ordic hamstring curl e ercise over a .83wee% period#&he e ercise, which is an eccentric hamstring curl,was performed as part of a wor%out . + ) times perwee%, for ) + 8 sets of + .( repetitions#

What ha))ened3

amstring strain in!ury incidence&he researchers reported that overall injury incidencerate was (#* per .,((( player hours# &his differed

between training <(#88 per .,((( player hours> andcompetition <.#) per .,((( player hours># In addition,it differed between groups, with the "ordic hamstringcurl group e periencing (#) injuries per .,((( playerhours and the non3training group e periencing (#9(injuries per .,((( player hours#

9dds ratios&he researchers found that the ris% of hamstring straininjuries <as calculated by the odds ratio> wassignificantly lower in the "ordic hamstring curl groupcompared with the non3training group <(#)9 times>#

Com#liance&he researchers found that the compliance with the"ordic hamstring curl protocol was ?.0, indicatingthat the soccer players were capable of underta%ingthis additional training without difficulty# &he instancesof failed compliance occurred partly as a result of players complaining of delayed onset muscle sorenessfrom the e ercise#

What did the researchers conclude3&he researchers concluded that regularly performingthe "ordic hamstring curl e ercise during trainingsignificantly reduces hamstring injury incidence inamateur soccer players#

0imitations

&he study was limited in that it was performed inamateur soccer players and it is unclear whether thesame results would be observed in other populations#




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Eccentric hamstring strength and hamstring in!ury ris& in )ustralian 1ootballers/ by 9#ar/ Gilliams/ Timmins/

ic&ey/ 0uhig/ and 'hield/ in Medicine 'cience in'#orts E"ercise 4 -56K 8

Background

Hamstring strains are a common injury in manypopular team sports and they lead to the loss of manyhours of training and competition, as well as a veryhigh re3injury rate# 2or a detailed introduction tohamstring strains, see the preceding study review#

*B+EC,I-E. &o assess prospectively whether lowhamstring strength and between3limb imbalances ineccentric strength, as measured by reference to the"ordic hamstring curl, are ris% factors for hamstringstrain injury in elite 'ustralian 2ootball athletes#

P*P/0A,I*1. ).( elite 'ustralian 2ootballers, aged

)8#8 L 8#* years, from different teams#

What ha))ened3

amstring strain in!ury incidence&he researchers reported that )9 hamstring strainsoccurred# &hey noted that *?0 were observed in thebiceps femoris long head, .90 occurred in thesemimembranosus, and just 80 were observed in thesemitendinosus# &hey found that high3speed runningwas the most common mechanism of injury <-.0>followed by %ic%ing <.90> and finally running whilebent over to collect the ball <*0>#

Effect of hamstring strength

&he researchers noted that low eccentric hamstringstrength, as defined by %nee fle ion force of ) -" atthe start of the preseason during the "ordic hamstringcurl, was associated with a )#* times greater ris% of hamstring strain in the season, as assessed by therelative ris%# Similarly, having low eccentric hamstringstrength, as defined by %nee fle ion force of )*?" atthe end of preseason was associated with a =#8 timesgreater ris% of hamstring strain in the season, asassessed by the relative ris%#

What did the researchers conclude3&he researchers concluded that having low levels of eccentric hamstring strength as measured during the

"ordic hamstring curl was associated with anincreased ris% of future hamstring strain injury#

0imitations&he study was limited by the cross3sectional design#6ongitudinal studies are re$uired to demonstrate thebeneficial effects of eccentric hamstring training onthe incidence of hamstring strain injury#




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Immediate effects of neurodynamic sliding versusmuscle stretching on hamstring fle"ibility in sub!ectswith short hamstring syndrome/ by CastelloteCaballero/ =alenza/ Puentedura/ 1ern@ndez de lasPe as/ and )lbur(uer(ue 'end?n/ in 3ournal of '#ortsMedicine 4 -56K 8

Background/anual therapies are widely used in order to increasefle ibility# However, the means by which thesetechni$ues increase joint range of motion is veryunclear# 2or a detailed introduction to this area, seethe preceding study review#

*B+EC,I-E. &o compare the effects of an isolatedneurodynamic sciatic sliding techni$ue with staticstretching and with a placebo on hamstring fle ibility<as measured by reference to passive straight legraise test> in otherwise asymptomatic individuals withlimited hamstring fle ibility <also %nown as shorthamstring syndrome>#

P*P/0A,I*1. .)( subjects <-( males and -(females>, aged 88#= L *#= years, with short hamstringsyndrome <as defined by a range of motion <1@/> of

9( degrees on the passive straight leg raise test>,randomly allocated to . of 8 groups7 neurodynamicsliding, static stretching, and placebo#

I1,E -E1,I*1. Subjects in the static stretchinggroup received an acute intervention involving passivestraight leg raise in the supine position performed byan e aminer for - sets of 8( seconds each# &heneurodynamic sliding comprised the same volume of concurrent hip fle ion and %nee fle ion movements,alternating dynamically with concurrent hip e tension

and %nee e tension movements, also in the supineposition# 2inally, the placebo group received passivemobili ation of the intrinsic foot joints in the supineposition, for the same volume of time#

What ha))ened3

amstring fle"ibility &he researchers reported that passive straight legraise test 1@/ increased to a greater e tent in theneurodynamic and static stretching groups comparedto the placebo group# However, they also found thatthe neurodynamic group increased passive straight legraise test 1@/ to a greater e tent than the staticstretching group#

What did the researchers conclude3&he researchers concluded that neurodynamic slidingtechni$ues appear to be able to improve hamstringfle ibility at least as well as static stretching, if not toa greater e tent#

0imitations&he study was limited in that it was an acuteinvestigation and it is unclear whether long3termbenefits of neurodynamic sliding would be similar tothose observed following long3term programs of staticstretching#


http://www.hindawi.com/journals/jsm/2014/127471/abs/

http://www.hindawi.com/journals/jsm/2014/127471/abs/

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'hort term effectiveness of neural sliders and neural tensioners as an ad!unct to static stretching of hamstrings on &nee e"tension angle in healthy individuals: a randomized controlled trial/ by 'harma/%althillaya/ ;ao/ and Mani/ in Physical Thera#y in'#ort 4 -567 8

Background/anual therapies are widely used in order to increasefle ibility# However, the means by which thesetechni$ues increase joint range of motion is veryunclear# 2or a detailed introduction to this area, seethe preceding but one study review#

*B+EC,I-E. &o compare the effects of two differentcombined neural and static stretching treatments withstatic stretching only on changes in hamstringfle ibility <as measured by passive %nee e tensionangle> in individuals with low hamstring fle ibility#

P*P/0A,I*1. -( healthy subjects, aged )) L )#=

years with low hamstring fle ibility, randomly allocatedto 8 groups, receiving a combined treatment of staticstretching and neurodynamic sliders, a combinedtreatment of static stretching and a neurodynamictensioner, or static stretching only#

I1,E -E1,I*1. 'll groups received a treatment of static stretching, comprising a 8(3second holdperformed by an e aminer with the subject supine andstarting in ?( degrees of hip and %nee fle ion with thefoot in plantar fle ion before performing assistedpassive %nee e tension# &he neurodynamic slider is atype of neural mobili ation in which the subject beginsseated, with the hands placed behind the bac%# &hecervical spine was e tended passively by an e aminer

while the subjects actively e tended both %nees whileperforming ma imum an%le dorsifle ion# &hen thecervical spine was fle ed passively by the e aminerwhile the subjects fle ed both the %nees# &heneurodynamic tensioner was performed in a similarway to the neurodynamic slider but tension wasapplied to the an%le by the e aminer during themovement#

What ha))ened3&he researchers found that all treatments led tosignificantly increased passive %nee e tension angle#&hey found that both combined treatments weresignificantly superior to the static stretching only

intervention but there were no significant differencesbetween the two combined treatments#

What did the researchers conclude3&he researchers concluded that both neural sliders andneural tensioners are more effective for increasinghamstring fle ibility compared with static stretchingalone# However, they also concluded that neitherneural mobili ation techni$ue was superior to theother#

0imitations&he study was limited in that it was unclear whetherthere was no difference between the two neuralmobili ation techni$ues because they produced similareffects through different mechanisms or because theyproduced similar effects by the same mechanism#


http://www.sciencedirect.com/science/article/pii/S1466853X15000140

http://www.sciencedirect.com/science/article/pii/S1466853X15000140

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Effectiveness analysis of active stretching versusactive stretching #lus low fre(uency electrical stimulation in children who #lay soccer and who havethe short hamstring syndrome/ by Pi(ueras;odr?guez/ Palaz<n %ru/ and +il +uillLn/ in Clinical

3ournal of '#ort Medicine 4 -567 8

BackgroundPain management is a %ey feature of many casespresenting to physical therapists and sports medicinephysicians# &raditionally, analgesic medication hasbeen the primary treatment for most types of pain#However, some medications have side effects that areundesirable, such as non3steroidal anti3inflammatorydrugs <"S'I:s>, which are thought to interfere withadaptations to e ercise# &ranscutaneous electricalnerve stimulation <&E"S> is a non3invasive method forpain relief# &E"S units can be purchased by individualswithout prescription in many countries around theworld# &he &E"S unit transmits pulsed electricalsignals across the surface of the s%in via self3adhesiveelectrodes# Pulse durations tend to be around ( +) (Ys, while fre$uencies tend to range from . + )((pulses per second# 1esearch into the potentialmechanisms underlying the analgesic effects of &E"Sunits suggests that they may reduce ongoingnociceptive cell activity and sensiti ation in the centralnervous system for ) hours, when applied acutely#1esearch into the pain3relieving effects compared to aplacebo have reported some degree of effectiveness,even when compared with a directly comparable shamtreatment# However, the e tent to which thesefindings are clinically meaningful is uncertain#

*B+EC,I-E. &o compare the effects of staticstretching with a combined treatment of activestretching plus &E"S on hamstring fle ibility <asmeasured by reference to passive straight leg raisetest, passive %nee e tension test, and toe3touch test>in young athletes with limited hamstring fle ibility#

P*P/0A,I*1. . young soccer players <aged .( +.- years> with limited hamstring fle ibility <asmeasured by reference to *( degrees in the passivestraight leg raise test or C. degrees in the passive%nee e tension test>, otherwise %nown as shorthamstring syndrome, randomly allocated to either anactive stretching group, an active stretching plus &E"Sgroup, or a normal activity group#

I1,E -E1,I*1. &he subjects too% part in 9treatment sessions over an 93wee% program of staticstretching or active stretching plus &E"S or a controlgroup who continued normal activities, which includedsome stretching# &he active stretching programcomprised ) sets of - repetitions of each of 8

commonly3used hamstring static stretching e ercisesperformed to the ma imum tolerable range of motionwithout pain for . seconds, with . seconds of restbetween stretches#

What ha))ened3

Combined static stretching #lus TEN'&he researchers found that the combined groupimproved passive straight leg raise test by .)#8degrees on the right and .(#( degrees on the leftcompared to the control# &hey reported that passive%nee e tension test improved by .)#? degrees on theright and 9#- degrees on the left compared to thecontrol# 2inally, they found that the combined groupimproved toe touch distance by 9#9cm compared tothe control group#

'tatic stretching only &he researchers found that the stretching3only groupimproved passive straight leg raise test by -#9 degreeson the right and #9 degrees on the left compared tothe control# &hey reported that passive %nee e tensiontest did not improve compared to the control# 2inally,they found that the stretching3only group improvedtoe touch distance by -#*cm compared to the controlgroup#


&he researchers concluded that a long3term programof active stretching plus &E"S was superior to a long3term program of active stretching only for increasinghamstring fle ibility#

0imitations&he study was limited in the control group alsoperformed some stretching activities as part of theirnormal soccer training#


http://pdfs.journals.lww.com/cjsportsmed/9000/00000/Effectiveness_Analysis_of_Active_Stretching_Versus.99659.pdf

http://pdfs.journals.lww.com/cjsportsmed/9000/00000/Effectiveness_Analysis_of_Active_Stretching_Versus.99659.pdf

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The structural and mechanical #ro#erties of the )chilles tendon - years after surgical re#air/ by +eremia/ %obbert/ Nova/ 9tt/ 0e )guiar ,emos/ 0e9liveira ,u#ion/ and =az/ in Clinical %iomechanics4 -567 8

Background&endons are connective tissue structures that connectmuscle to bone and permit the transference of tensileforce from the muscle to its associated joint# However,tendons are not simply inactive structures thattransmit muscle force# &hey have specific mechanicalcharacteristics that affect movement and function#:espite being non3contractile tissues, they perform arole in human movement by means of energyconservation and material deformation# /orespecifically, they have viscoelastic properties, whichmeans that they display both elastic and viscouscharacteristics, depending on the amount of loadapplied and on time for which this load is applied# &heelastic properties of tendons have been of particularinterest to researchers wor%ing in sport science# 2ore ample, it has been noted that the 'chilles tendonfunctions as a biological spring during locomotion#:uring the early stance phase of gait, these tendonshave been found to store elastic energy andsubse$uently release it in the late phase, therebyenhancing efficiency of movement# Increasing theability of tendons to store and release energy duringmovements would be highly valuable to athletes, as atendon that stored and released a greater amount of energy per foot stride would lead to greater propulsionfor the same amount of muscular force# 'natomically,tendons are comprised in a hierarchical format of individual collagen structures# Similar to the structureof muscles, tendons are comprised of single strands of fibrils, made of collagen, which are bundled togetherma%ing increasingly larger structures7 many fibrilsbecome fibers, many fibers become fascicles, whichultimately become the constituents of the wholetendon comple # Each bundle is tightly pac%ed andsurrounded by a connective sheath, %nown as anendotendon# &endons are mostly made from type Icollagen material, which is considered to beresponsible for the strength of the material againstdeformation, although tendons do also contain othertypes of collagen, most obviously type III collagen,which has been implicated in the healing process of tendon, but also seems to wea%en the tendon

structure if too much is present# 'dditionally, thee act components of a tendon depend upon its preciselocation in the body# &endons seem to respond tocertain mechanical loading protocols by increasingtheir si e, measured as cross3sectional area# 2ore ample, some researchers have observed changes intendon cross3sectional area following long3termprograms of resistance training# However, the e actimplications of such changes are not entirely clear#

*B+EC,I-E. &o compare the effects of early andtraditional immobili ation rehabilitation programs onthe mechanical properties of injured and surgicallyrepaired 'chilles tendons, ) years post3repair# &hemechanical properties investigated were assessed bymeasuring tendon cross3sectional area, tendon restinglength, and tendon elongation as a function of tor$ue

in ma imal voluntary isometric contraction </DI;>plantar3fle ion by ultrasound# &hese measurementsallowed the calculation of length3tension and stress3strain relationships#

P*P/0A,I*1. .9 males who had suffered previous'chilles tendon rupture, including ? subjects who hadreceived early mobili ation treatment and ? subjectswho had received traditional immobili ation with aplaster cast#

What ha))ened3

,ength tension relationshi#&he length3tension relationship of tendons describes

how much they elongate in response to applied force#&he researchers found that the previously injuredtendons displayed lower force for the same elongationby T).0 <effect si e G .#=># However, they found nodifferences between rehabilitation treatment methods#

'tress strain relationshi#&he stress3strain relationship of tendons is similar tothe length3tension relationship and also describes howmuch they elongate in response to applied force butcontrols for the cross3sectional area <stress ratherthan force> and the resting length <strain rather thanlength># &he researchers found that the previouslyinjured tendons displayed lower stress for the samestrain by T)(0 <effect si e G .#.># However, theyfound no differences between rehabilitation treatmentmethods#

What did the researchers conclude3&he researchers concluded that the mechanicalproperties of previously ruptured and surgicallyrepaired tendons ) years post3repair are not affectedby the type of rehabilitation method that is conductedimmediately after surgery# &hey therefore suggestthat early mobili ation treatment is as appropriate astraditional rehabilitation#

0imitations

&he study was limited in that it is unclear whetherthere is a rehabilitation approach that can beperformed that will indeed allow tendons to revertbac% to their original state of mechanical function#


http://www.sciencedirect.com/science/article/pii/S0268003315000704


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uman tendon ada#tation in res#onse to mechanical loading: a systematic review and meta analysis of e"ercise intervention studies on healthy adults/ by %ohm/ Mersmann and )ram#atzis/ in '#orts Medicine

9#en 4 -567 8

Background&endons are connective tissue structures that connectmuscle to bone and permit the transference of tensileforce from the muscle to its associated joint# However,tendons are not simply inactive structures thattransmit muscle force# &hey have specific mechanicalcharacteristics that affect movement and function# 2ora detailed bac%ground to tendons, see the previousstudy review#

*B+EC,I-E. &o perform a systematic review andseveral meta3analyses of the literature in relation tothe effects of long3term mechanical loading onasymptomatic human tendons#

S,/56 SE0EC,I*1. Studies were included thatdescribed the effects of long3term e ercise programs

<Z9 wee%s> in healthy humans aged .9 + ( years onthe mechanical, material or morphological propertiesof tendons# /echanical properties were predominantlyreported in relation to tendon stiffness materialproperties were predominantly reported in relation tothe stress3strain relationship and the morphologicalproperties were predominantly reported in relation totendon cross3sectional area#

What ha))ened3

'tudy selection&he reviewers identified )* studies with 8* separateinterventions on either the 'chilles or patellar tendon,including a total of )-= subjects#

Effects of mechanical loading on tendons&he researchers observed that mechanical loading hassignificant effects on tendon stiffness <effect si e G(#*(>, the stress3strain relationship <effect si e G(#-?> and on tendon cross3sectional area <effect si eG (#)=># &hey noted that there was significantheterogeneity between study protocols for tendonstiffness and for the stress3strain relationship but notfor tendon cross3sectional area#

)nalysis of #rogram characteristics&he researchers assessed which e ercise programcharacteristics were driving the heterogeneity of theresults found in the main meta3analyses for tendon

stiffness and for the stress3strain relationship# &heyfound that tendon stiffness was mar%edly affected byrelative load, with loads C*(0 of ma imum voluntaryisometric contraction </DI;> being superior to loads

*(0 of /DI;# However, there was no effect of contraction type <e#g# isometric vs# dynamic># &heyalso found that tendon stiffness was mar%edly affectedby the duration of the intervention, with durations of C.) wee%s being superior to durations of .) wee%s#

What did the researchers conclude3&he researchers concluded that tendons respond toincreased mechanical loading by altering mechanical,material, and morphological properties# &hey also

concluded that more effective training interventionsinvolve high relative loads <C*(0 of /DI;> overlonger durations <C.) wee%s>#

0imitations&he meta3analysis was limited in that it is unclear towhat e tent changing the mechanical, material, andmorphological properties of tendons in the waysobserved in the included studies is beneficial for sportsperformance or general health#


http://www.sportsmedicine-open.com/content/1/1/7#abs

http://www.sportsmedicine-open.com/content/1/1/7#abs

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Preventive interventions for tendino#athy: asystematic review/ by Peters/ Awerver/ 0ierc&s/Elferin& +emser/ =an den )&&er 'chee&/ in 3ournal of 'cience and Medicine in '#ort 4 -567 8

Background

&endinopathy is usually ta%en as a generic termdescribing any abnormal tendon condition, althoughthere is some disagreement about the e act usage of the nomenclature# Some researchers and cliniciansconsider that the term tendinopathy encompassesboth tendinitis and tendinosis# However, othersconsider that only long3term structural changes can beconsidered tendinopathy and where tendinitis involvesonly transitory inflammation, this would not beclassified as tendinopathy# 1esearchers holding to thisdefinition suggest that the structural changesassociated with tendinopathy include increasedcellularity, increased vascularity, a tendency for cellsto become more rounded rather than elongated,greater glycosaminoglycan deposition, calcificationand lipid deposition# &endinitis is usually definedpurely as the inflammation of a tendon and is thoughtto arise from micro3tears following from acuteoverloading of the muscle3tendon unit by anune pected or e cessively large tensile force# @n theother hand, the term tendinosis describes thedegeneration of tendon collagen in response to chronicoveruse# It is thought that tendinosis arises wherechronic damage occurs without the tendon havingtime to heal <as occurs in the case of repetitive straininjury># In any event, tendinopathy, however it isdefined, involves activity3related pain, tenderness,locali ed swelling and disability# It is thought toaccount for up to half of all sports injuries and ishighly prevalent in athletes who participate inactivities involving repetitive movements# ;ommonly3occurring tendinopathies seen by sports medicinephysicians and physiotherapists include patellar,'chilles, lateral epicondyle of the elbow, and rotatorcuff of the shoulder# &endinopathy has traditionallyvery commonly been treated conservatively withstretching and now more recently with eccentrice ercise# However, the e act mechanisms by whichsuch modalities are effective is unclear# Someresearchers have suggested that eccentric e ercisehelps stimulate remodeling of the tendon structure bychanging blood and fluid flow but this is far from beingapparent#

*B+EC,I-E. &o carry out a systematic review of theefficacy of preventive interventions for tendinopathy atthe an%le, %nee, hip, groin, shoulder and elbow#

S,/56 SE0EC,I*1. Studies were included thatassessed the preventive effects of an intervention fortendinopathy <as measured by either the incidence or

prevalence of either tendinopathy itself or of tendonabnormalities> in a specific tendon of the an%le, %nee,hip, groin, shoulder or elbow#

What ha))ened3

'tudy selection&he researchers identified .( articles that involved 8types of intervention7 stretching and e ercise, shoeadaptations, and other unclassified interventions#&hese articles included = investigations of stretchingand e ercise, 8 e plorations into the effects of shoeadaptations, and ) other unclassified interventions#&he studies e plored ? preventive interventions for'ch ill es tendinopathy, ) preventive interventions for

patellar tendinopathy, and . preventive interventionfor groin tendinopathy#

Efficacy of #reventative interventions&he researchers found that of the = investigations of stretching and e ercise, only . reported a beneficialeffect, which was the use of soccer3specific balancetraining# &hey noted that of the 8 investigations intoshoe adaptations, only . reported a beneficial effect,which was the use of shoc%3absorbing insoles forpreventing 'chilles tendinopathy# &he unclassifiedcategory included one study that assessed the effectof Hormone 1eplacement &herapy <H1&>, whichseemed to be beneficial, and one study that assessedthe benefit of information provision, which did not#

What did the researchers conclude3&he researchers concluded that there is limitedevidence that a long3term intervention of soccer3specific balance training may be effective forpreventing patellar and 'chilles tendinopathy, whileshoc% absorbing insoles may also be effective forpreventing 'chilles tendinopathy# &hey noted that H1&seems to reduce the ris% of 'chilles tendinopathy inpost3menopausal women#

0imitations&he review was limited by the relative paucity of

literature in this area#




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'i" wee&s of core stability training im#roves landing&inetics among female ca#oeira athletes: a #ilot study/ by )rau!o/ Cohen/ and ayes/ in 3ournal of

uman *inetics 4 -567 8

Background

;ore stability has been subject to a large amount of research, both with a view toward improving athleticperformance and to preventing and treating low bac%pain <6 P># However, in the literature, there has beenconsiderable variety between studies in respect of what is defined by both the core and by stability#/oreover, stability re$uirements may differ underdifferent loading conditions, particularly as the corecan be subject to indirect forces applied from a varietyof different directions and also in response to forces of varying durations and magnitudes# &hus, the conceptof core stability is e tremely difficult to pin downaccurately# ;ore stability is thought to be importantfor athletes because of the transfer of force from theupper body segments to the lower body and from thelower body segments to the upper body in a processcalled se$uential %inetic lin%ing# 1esearchers havepreviously outlined how the acts of baseball pitchingand batting follow a se$uential %inetic chain# &hisphenomenon describes motions that follow a pro imal3to3distal pattern, which are initiated by larger, centralbody segments and then proceed outward to thesmaller, more distal segments, such as the arms#Where optimal pro imal3to3distal %inematic se$uencesoccur in throwing motions, the pelvis is rotated usingthe leg and hip muscles# &he pelvis initially acceleratesbut then $uic%ly decelerates as it transfers energy tothe torso# &he same pattern is repeated with the torsoand the arm and then the arm and the hand or bat#:uring this se$uence, it is thought that the activationof the core muscles acts to decelerate pelvic rotationand accelerate rotation of the upper trun%# "ot allresearchers have considered the important role of thetrun% muscles in such se$uences when attempting todefine core stability for athletes# /any genericdefinitions have been proposed defining core stabilityas the integrated functioning of the spine andsurrounding muscles to maintain intervertebral rangeof motion within a safe limit# Such definitions fall shortnot only of ta%ing the role of the trun% in athleticmovement into account but also in that they e cludethe abdominal musculature <with the %ey ones beingthe transverse abdominis, rectus abdominis, e ternal

obli$ue, and internal obli$ue>, which are also thoughtto have a %ey role in core stability# In possibly themost important definition of core stability, Nibler et al#<)((- > described it as OOthe ability to control theposition and motion of the trun% over the pelvis toallow optimum production, transfer and control of force and motion to the terminal segment inintegrated athletic activities#B "evertheless, it is highlyli%ely that the current failure to uncover meaningfulfindings in this area of research is at least partlycaused by the failure to define terms appropriately#

*B+EC,I-E. &o assess the effects of a core stabilityintervention on landing ground reaction forces <usinga force plate> during a drop jump test <from a boheight of =(cm> in trained individuals#

P*P/0A,I*1. .- female capoeira athletes, aged)*#8 L 8#* years#

I1,E -E1,I*1. 'll subjects performed static anddynamic core stability e ercises, 8 times per wee% for- wee%s# E ercises included the plan%, the side plan%,the supine bridge, the abdominal crunch, the 1ussiantwist, and the split leg scissors, all of which wereperformed for 8 sets of 8( + = 3second holds or 8 setsof )( + = repetitions, as appropriate#

What ha))ened3

=ertical ground reaction forces&he researchers observed a significant reduction inrelative vertical ground reaction force upon landing forboth the first landing phase <8#=( L (#*9 vs# )#9 L

(# )" per " of bodyweight> and also for the secondlanding phase < #(? L .#.* vs# 8#() L (#=." per " of bodyweight>#

3um# height &he researchers observed that jump height was notsignificantly altered as a result of the core stabilityprogram#

What did the researchers conclude3&he researchers concluded that trun% dominant corestability training reduces ground reaction forces duringlanding without altering jump height in femaleathletes, which may in turn reduce lower body injuryris%#

0imitations&he study was limited as it is unclear which e ercisesin the battery were most effective at bringing aboutthe beneficial effects#






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Core strength training for #atients with chronic low bac& #ain/ by Chang/ ,in/ and ,ai/ in 3ournal of Physical Thera#y 'cience 4-5678

Background6ow bac% pain <6 P> can be defined as pain that is

locali ed to the lumbar area, below the inferior ribcageand above the waistline, although the definition is alsooften e tended to include radiating leg pain such assciatica# 6 P is a common and growing problem# Itleads to a large number of physician3related visits inboth the Mnited States and worldwide# In the MnitedStates in .??(, around . million visits were recordedfor mechanical 6 P, causing this problem to ran% asthe fifth most li%ely out of all physician visits#Economically, the burden of 6 P is severe# :irect andindirect costs of 6 P have been estimated as aroundU ( + U.(( billion per annum, with * 0 of thesecosts being attributable to the 0 of people whobecome disabled# 'dditionally, a great deal of timeand money appears to be spent on procedures thatare ineffective# 1eviews of the various treatmentscurrently in use for individuals with 6 P have oftenconcluded that patients are receiving an increasingnumber of treatments that are poorly supported byevidence# Such treatments often come accompaniedby complications# When analy ing 6 P, it is thought tobe important to distinguish between acute and chronic6 P, although the literature itself can be conflicting inthis regard# ;ommonly acute 6 P is defined as thatlasting - wee%s, sub3acute 6 P is usually defined as- + .) wee%s, and chronic 6 P is usually defined asC.) wee%s# In respect of acute 6 P, researchers havegenerally found that no intervention is more successfulthan the simple advice to remain active# &his is indeedthe recommendation of current guidelines# 'lso, thesesame guidelines suggest that the vast majority of incidences of acute 6 P resolve in - wee%s# However,a recent meta3analysis found that while cases of acute6 P did improve mar%edly within - wee%s, the speedimprovement after this point slowed and low3to3moderate levels of pain and disability were stillpresent C. year later# ;hronic 6 P is very differentfrom acute 6 P both in the prognosis and in theavailability of effective treatments# Mnli%e acute 6 P,researchers have generally found that e erciseinterventions lead to both statistically significant andclinically useful differences in outcomes in comparisonwith other treatments, including usual treatment by

general practitioners# 'dditionally, unli%e acute 6 P,the recurrence rate for chronic 6 P is very high, withmany people suffering repeated episodes over longperiods of time#

*B+EC,I-E. &o perform a systematic review of thenew literature in relation to the effectiveness of coretraining for improving pain, function and $uality of lifein patients with chronic 6 P#

S,/56 SE0EC,I*1. Studies published after )((9that e plored the effects of long3term core training

interventions on direct measures of 6 P severity wereincluded#

What ha))ened3

'tudy selection&he researchers only identified = relevant studies inthe period from )((9 onwards, although these wereall high $uality per the [adad scores# &hese studieseach used different training approaches, as follows7trun% strengthening, core stabili ation, segmentalstabili ation of the deep core muscles, and motorcontrol e ercises# &he studies also assessed theeffects of training on different outcome measures# 2orpain measurements the Disual 'nalog Scale for pain

<D'S> and the /c4ill pain $uestionnaire were used#2or function measurements, the range minimum $uery<1/\>, @swestry disability $uestionnaire <@SW:\>and the bac% performance scale < PS> were used# 2or$uality of life, the Short 2orm3.) <S23.)> physical andmental sections were used#

Effects of core training&he researchers found that pain measurements wereimproved by all core training methods, as measuredby either the D'S or /c4ill pain $uestionnaire testresults# However, the improvement may have beensimply in line with the natural course of the condition,as these effects were not different from the non3training control groups# &he researchers also notedthat function and $uality of life were improved by coretraining and these effects were greater than the non3training control groups#

What did the researchers conclude3&he researchers concluded that a range of commonly3used core training methods can help improve functionand $uality of life <and possibly reduce pain> in casesof 6 P, although it is unclear whether any specific coretraining method is superior#

0imitations&he review was limited in that only recent studies

were incorporated, which may present an unbalancedview of the literature#


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E"ercise based #erformance enhancement and in!ury #revention for firefighters: contrasting the fitnessand movement related ada#tations to two trainingmethodologies/ by 1rost/ %each/ Callaghan/ and Mc+ill/ in The 3ournal of 'trength Conditioning;esearch 4 -567 8

Background&he 2unctional /ovement Screen <2/S> is a test inwhich * different movements are graded from . + 8points# &he sum of these tests is ta%en to create atotal score out of ). points# 1esearchers have shownthat when using a cut3off point of .= points, it ispossible to use the sum score to predict injury ris%,albeit with a relatively low degree of accuracy# Msingthe cut3off of .= points, the ability of the 2/S topredict correctly individuals who will incur an injury<i#e# sensitivity> is in fact on average across a range of studies $uite poor <i#e# T (0, which is the same as acoin toss># @n the other hand, the ability to predictcorrectly those individuals who will not incur an injury<i#e# specificity> is much better# &his suggests that the2/S is superior for identifying individuals who will notbe injured than it is for identifying at3ris% cases# &hus,the 2/S might serve best as a screen for clearingathletes from unnecessary injury prevention trainingrather than as an injury ris% detection screen# Severalstudies have found that the inter3rater and intra3raterreliability of the 2/S is good3to3e cellent, particularlywhere e perienced raters perform the tests# However,the use of the sum score of the 2/S to predict injuryhas been $uestioned by researchers who haveassessed its validity# In one investigation, the factorstructure of the 2/S test was e plored and it wasfound that there was poor correlation between theoutcomes of the various individual component tests,meaning that the validity of combining the scores of each test within the 2/S to produce a sum score topredict injury ris% is $uestionable# :espite theseconcerns, the 2/S sum score continues to be widely3used as a test of injury ris%# ;onventionally, whereindividuals score poorly on the 2/S, e erciseinterventions are recommended to improve the scoreand, it is believed, reduce future injury ris%# Indeed, itis well3%nown that e ercise, particularly resistance3training, does lead to alterations in joint anglemovements observed during multi3joint movements,such as drop landings# /any studies have assessedthe ability of different e ercise intervention programs

to improve the 2/S score in various populations# 'ndalmost all have found that e ercise can improve 2/Sscore# However, these studies were of relatively low$uality and the only high3$uality study was the singleone that reported that e ercise was not able toimprove 2/S score in relation to a control group#However, in the studies that have compared correctiveor functional e ercise with traditional resistancetraining, the 2/S recorded no differences inimprovement in 2/S score between the two trainingprograms#

*B+EC,I-E. &o compare the effects of two differenttraining programs on both fitness and movementadaptations# 2itness was assessed by reference toseveral tests, including7 an incremental treadmill testfor aerobic fitness, a grip test for muscular strength<measured using a hand dynamometer>, dynamicmuscular endurance <measured by reference to the

ma imum number of push3ups>, static muscularendurance for the core <front plan%, side plan% and

ierring3Sorensen bac% e tension> tests, lower3bodypower <by reference to the pro y of counter3movement jump height, and lower3body fle ibility <asmeasured in the modified sit3and3reach test>#/ovement was assessed by reference to the degree of spinal movement and frontal plane %nee movement in

tas%s7 a bo lift, a bodyweight s$uat, a lunge, aone3arm push with a split stance, and a one3arm pullwith a split stance# &hese movements were performedunder = conditions7 low3load and low3velocity, high3load and low3velocity, low3load and high3velocity, andhigh3load and high3velocity#

P*P/0A,I*1. ) firefighters randomly allocated to amovement3guided fitness group, a conventional fitnessgroup, or a non3training control group# &he subjects ineach group were tested with the 2/S and all hadsimilar scores#

I1,E -E1,I*1. &he subjects in the training groupsperformed .)3wee% e ercise programs#

What ha))ened3&he researchers found that only the movement3guidedgroup displayed significant improvements in spine andfrontal plane %nee motion in each of the tas%s#However, while the group displayed significant

improvements in each of the tas%s when performedwith at least one combination of load and velocity,they did not display significant improvements in allconditions of load and velocity similarly#

What did the researchers conclude3&he researchers concluded that a long3term programof movement3based coaching can alter how subjectsperform certain standardi ed tas%s#

0imitations&he study was limited in that it was unclear preciselywhat aspects of the movement3guided fitness programmight have contributed to the beneficial effectsobserved in the tests#




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%alancing hands on with hands off #hysical thera#y interventions for the treatment of central sensitization #ain in osteoarthritis/ by +irbLs/ Meeus/%aert/ and Ni!s/ in Manual Thera#y 4 -56K 8

Background

@steoarthritis is a chronic, progressive, degenerative joint disorder# It is characteri ed by constellation of damaging structural changes in a joint, including theareas of articular cartilage and subchondral bone,which can be observed on ]3ray imaging scans# &hesechanges are thought to be instrumental in thedevelopment of pain and functional impairment#@riginally, osteoarthritis was thought to be entirely adisease of the articular cartilage but more recentresearch has revealed that the condition is amultifactorial disease of the whole joint, with acomple pathogenesis involving interactions betweenvarious joint tissues# @steoarthritis is an e tremelycommon condition and is becoming more prevalent,most li%ely because of the worldwide aging population#&he pathogenesis of osteoarthritis is unclear but ris%factors are thought to include age, race, gender, jointtrauma and life3style factors including obesity# Severalstudies have found that athletes and individualsparta%ing in sports are more li%ely to incurosteoarthritis in comparison with non3athletic controls#It has been proposed that this is because athletesmore fre$uently sustain joint injuries compared withnon3athletic controls rather than because of thegreater amount of physical activity# Indeed, previousligament injuries and meniscal tears are stronglyassociated with the subse$uent progression of osteoarthritis whereas e ercise is typically associatedwith amelioration of symptoms in affected individuals#&he primary symptoms of osteoarthritis are joint painand stiffness, which typically lead to reducedmovement and subse$uent disuse atrophy of therelated musculature# &reatment of osteoarthritis islimited but generally includes physiotherapy, e ercise,weight loss, and the relief of symptoms with localcorticosteroid injections, and the administration of analgesics and non3steroidal anti3inflammatory drugs<"S'I:s>#

*B+EC,I-E. &o discuss the available Adesensiti ingB strategies that are available to physical therapists andhow they can be applied when treating patients withchronic osteoarthritis3related pain#

What did the researchers 7ind3

%alance between hands on and hands off thera#y &he researchers note that there is evidence thatcentral sensiti ation plays a %ey role in the paine perienced by individuals with osteoarthritis, whichmay benefit from being addressed directly throughpsychosocial treatments# ut they also observe thatthis does not discount the presence of ongoingperipheral joint pathology that may benefit from moretraditional, locally3focussed interventions#

%enefits of #ain science education&he researchers note that education can play a %eyrole in addressing central sensiti ation, although thestandard materials tend to involve the provision of biomedical information, which can increase fear and

reinforce belief in a pathological, anatomical source of pain, which aggravates the condition# &he researcherstherefore suggest pain science education, which istargeted towards a reconceptuali ation of pain that isintended to change pain beliefs, thereby desensiti ingthe central nervous system#

Clarifying the mechanisms of manual thera#y &he researchers suggest that care be ta%en during theprovision of manual therapy to avoid referring tounjustified mechanisms of action that imply structuralchanges are occurring# In this way, manual therapycan be seen as an intervention to help improvefle ibility transiently and also to provide temporarypain relief through the activation of descendinginhibitory pain mechanisms#

What did the researchers conclude3&he researchers concluded that while there may besome problems in combining manual therapy and painscience education for addressing central sensiti ationin individuals with chronic osteoarthritis3related pain,it is possible to combine these effectively#

0imitations&he review was limited in that was based upon theopinions of the reviewers and may not reflect theviews of all researchers wor%ing in this field#




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,oss of range of motion of the hi# !oint: a hy#othesisfor etiology of s#orts hernia/ by ;ambani and

ac&ney/ in Muscles/ ,igaments and Tendons 3ournal 4-5678

Background

Hip e tension is very probably the most important joint action in all of sports and is also %ey to beingable to perform functional activities of daily living#'lthough the hip joint is a ball3and3soc%et joint and iscapable of movement in every direction, hip e tension<and fle ion> is the joint action that occurs in thesagittal plane and facilitates the activities of wal%ingand running# Hip e tension range3of3motion <1@/> isoften lost in injured or elderly people# Indeed, studieshave reported that hip e tension 1@/ is the only formof hip 1@/ to decrease significantly with age and thata reduction in hip e tension 1@/ occurs between the) + 8? and =( + ? years age groups, which amountsto T- degrees over the whole (3year duration of adult life# 'dditionally, active hip e tension 1@/ islower in elderly people who have a history of fallingcompared to elderly people who do not have a historyof falling# &his may be because the lac% of hipe tension 1@/ ma%es it more difficult to solvemovement problems or it may be because reduced hipe tension 1@/ leads to reduced hip e tensionstrength7 studies have found that a lac% of hipe tension 1@/ is associated with reduced hipe tension strength and that mobili ation of the hip

joint by a physical therapist can improve hip e tensionstrength in subjects with normal hip e tension 1@/#In addition, lower bac% pain is correlated withsignificantly reduced hip e tension 1@/, irrespectiveof the %nee fle ion angle and hip abduction angle#However, studies have reported that the end ranges inthe frontal plane appear to produce the greatestproblems for lower bac% pain sufferers# In normalpeople, research indicates that hip e tension 1@/ canvary widely# Some studies indicate that there issignificant hip e tension 1@/ of T. + )( degrees,while studies indicate that hip e tension 1@/ is muchless# &his may reflect large variability between groupsof subjects or it may be a function of differentmeasurement methods leading to varying results# @f course, hip e tension 1@/ is generally greater infemales than in males# However, it is important tonote that during combined forward hip and spinefle ion actions, such as the sit3and3reach test, there

are also other se differences in respect of the various joints# &his ma%es combined fle ibility tests li%e thesit3and3reach test problematic for assessing hipe tension in populations comprising both males andfemales# Hip e tension range3of3motion <1@/> fromthe neutral position, or hip hyper3e tension, can besignificantly affected by the degree of hip abductionand %nee fle ion# 1educing %nee fle ion from 9(degrees down to ( degrees allows much greater hip

*B+EC,I-E. &o assess whether a loss of range of motion of at the hip joint is associated with a greaterris% of sports hernia, potentially as a contributoryfactor to stress across the symphysis pubis leading toinstability#

P*P/0A,I*1. ) athletes with sports hernia and )

age3, se 3, physical or sports activity3 and co3morbidity3matched athletes without sports hernia#

What ha))ened3

i# fle"ion and e"tension ;9M &he researchers found that in the sports hernia and nosports hernia groups, the hip fle ion 1@/ was similar<.))#8( vs# .))#)( degrees> and the hip e tension1@/ was similar <.(#8( vs# ..#=( degrees>#

i# adduction and abduction ;9M &he researchers found that in the sports hernia and nosports hernia groups, the hip adduction 1@/ wassimilar <)*#.( vs# )-#)( degrees> and the hip

abduction 1@/ was similar <8 #)( vs# 8 #?( degrees>#i# internal and e"ternal rotation ;9M

&he researchers found that when comparing the sportshernia and no sports hernia groups, the hip internalrotation 1@/ was significantly less in the sports herniagroup <.*#=( vs# =(#?( degrees> and the hip e ternalrotation 1@/ was also significantly less in the sportshernia group <)-#)( vs# = #.( degrees>#

What did the researchers conclude3&he researchers concluded that the loss of hip internaland e ternal rotation 1@/ might be a predisposingfactor for greater ris% of sports hernia#

0imitations&he study was limited in that it was retrospective andcross3sectional and it is therefore unclear whether theloss of 1@/ was a causal factor for injury#

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