Posterior Rotator Cuff

Strengthening Using

Theraband® in a FunctionalDiagonal Pattern in Collegiate

Baseball PitchersPhillip A. Page, MS, ATC, EMT, LAT

John Lamberth, PhDBen Abadie, EdD

Robert Boling, PhDRobert Collins, MDRussell Linton, MD

rotator cuff. Effective strengthening ofeccentric muscles may be difficult toattain through traditional isotonic resis-tance exercises using light weights(approximately 5 lbs) in uniform move-ment patterns. Therefore, a more practi-cal, functional, and effective means ofeccentric strengthening of the posteriorrotator cuff must be developed.

The purpose of this study was todetermine if there was a significantincrease in eccentric strength of theposterior rotator cuff throughresistance exercise using TherabandElastic Band (Hygienic Corporation,Akron, Ohio) in a functional-diagonalpattern as opposed to a traditional iso-tonic resistance exercise routine usinglight weights in uniform movementpatterns during an in-season mainte-nance program for collegiate baseballpitchers.

Abstract: The deceleration phase ofthe pitching mechanism requires force-ful eccentric contraction of the posteri-or rotator cuf Because traditional iso-tonic strengthening may not be specificto this eccentric pattern, a more effec-tive and functional means of strength-ening the posterior rotator cuff is need-ed. Twelve collegiate baseball pitchersperforned a moderate intensity isoton-ic dumbbell strengthening routine for 6weeks. Six of the 12 subjects were ran-domly assigned to an experimentalgroup and placed on a Theraband®Elastic Band strengthening routine in afunctional-diagonal pattern to empha-size the eccentric contraction of theposterior rotator cuff in addition to theisotonic routine. The control group (n= 6) perforned only the isotonic exer-cises. Both groups were evaluated on aKIN-COM® isokinetic dynamometer in

Phillip A. Page is a physical therapy stu-dent at Louisiana State University in NewOrleans, LA 70112-2262.John Lamberth, Ben Abadie, and RobertBoling are assistant professors; RobertCollins is the team physician; and RussellLinton is a team orthopaedist. All are affil-iated with Mississippi State University.

a functional diagonal pattern. Pretestand posttest average eccentric forceproduction of the posterior rotator cuffwas compared at two speeds, 60 and1800/s. Data were analyzed with ananalysis of covariance at the .05 levelwith significance at 600/s. Values at180°/s, however, were not significant.Eccentric force production at 600/sincreased more during training in theexperimental group (+19.8%) than inthe control group (-1.6%). There wasno difference in the two groups at180°/s; both decreased (8 to 15%).Theraband was effective at 600/s infunctional eccentric strengthening ofthe posterior rotator cuff in the pitchingshoulder.

R5 ecent biomechanical and elec-tromyographic (EMG) studiesave determined that the mus-

cles of the posterior rotator cuff (theexternal rotators; supraspinatus, infra-spinatus, and teres minor) experienceeccentric contractions during the decel-eration and follow-through phases ofbaseball pitching. 3,5,1 2,1 7,'23,24,28,3 1Because the deceleration phase is stren-uous to the shoulder in regards totorque during deceleration,3'5'23'24 strongdecelerators are vital in the posterior

MethodsFor this study, two randomly

assigned groups exercised for 6 weeksusing a moderate-intensity isotonicmaintenance program. One groupexercised with Theraband (experimen-tal group); the other did not (controlgroup). Each group was pretested andposttested for average eccentricstrength of the posterior rotatorcuff.The independent variable wasthe mode of strengthening. The depen-dent variable was average eccentricstrength, measured in pounds of force.Inferentially, analysis of covariance(ANCOVA) was used to determineany significant difference, with thepretest scores statistically controlled.

Subjects (n = 12) were volunteermembers of the baseball team pitchingstaff participating in fall drills. By usingpreseason athletic participation physi-cals, we screened for any contraindica-tions to exercise before the onset of theinvestigation. We randomly assignedsix subjects to each of two groups.

Testing ProceduresSubjects were pretested and

posttested on a KIN-COM 125E isoki-netic dynamometer (Chattecx Corp,Hixson, Tenn). The dynamometer wascalibrated according to the manufac-turer's protocol before both testing

346 Volume 280* Number 4 * 1993

sessions. Isokinetic testing has beenfound to be reliable in assessingstrength. 15,20,37

Testing was performed within theweek before and the week after the 6-week strengthening trial. We testedindividuals in each group over thecourse of 2 days; right-hand dominantfirst, then left-hand dominant. Thesame examiner administered the teststo insure adherence to the testing pro-cedure through consistent positioning,instructions, and encouragement.Uniform instructions explaining thestudy, the procedures, and techniquesof the test were read to the partici-pants.

Each subject was positioned on theseat in a uniform fashion to adhere tothe test position protocol (Fig 1). TheKIN-COM dynamometer head wastilted at 300 and rotated as needed toallow the axis of rotation to passthrough the axilla. The seat level andtable-top length were positioned for-ward to accommodate this axis ofrotation through the axilla. Spacerswere placed between the subject'sback and the table seat for stabiliza-tion of the back. A stool placed underthe feet supported the legs. The sensorattachment pad was aligned in the

middle of the forearm between thewrist and the elbow. The upper bodywas secured to the seat with a velcro-fastened strap across the chest, and thepelvis was stabilized with a seat belt.Mechanized stops were placed justbeyond the computer stop and startangle to prevent any motion beyondthe range of motion defined by thepattern tested.

Each test was performed as fol-lows:1. Subject stretched his/her dominant

shoulder for 5 minutes.2. Subject was positioned on the

dynamometer and secured, asnoted above.

3. Uniform instructions were read.4. Subject was instructed to perform

the following: one repetition at"50% perceived maximum"; onerepetition at "75% perceived maxi-mum"; three repetitions at "100%perceived maximum."

Each repetition consisted ofresisted lengthening of the posteri-or rotator cuff in a functional pat-tern of deceleration: D2-extensionstarting position, then abduct-ion/flexion/external rotation, andending with adduction/extens-ion/internal rotation (Fig 2). As the

Fig 1.- Isokinetic test protocol start (a) and isokinetic test protocol finish (b).

subject performed the eccentriccontraction of the posterior rotatorcuff in the D2-extension pattern,the hand was kept open. For thereturn movement to the originalstarting position, the subject eccen-trically contracted the anteriorrotator cuff in the D2-flexion pat-tern in order to rest the posteriorrotator cuff. In this movement, thehand was closed.

5. The test was given at two speeds,first at 600/s and again at 180°/s inthe same position after a 1-minuterest.

6. Verbal motivation was given onlyas needed to keep the athlete inproper motion during the testing.

Strengthening ProceduresBoth groups stretched the rotator

cuff and performed isotonic exercisesusing a 5-lb dumbbell, as recommend-ed for shoulder strength mainte-nance.5'25'29'36 Each exercise was per-formed three times per week for oneset of 10 repetitions each. This tradi-tional isotonic routine (Fig 3) includedthe following exercises:

CircumductionAbductionBiceps CurlsTriceps ExtensionsStanding supraspinatus "Empty-can"

Posterior Cuff External RotationHorizontal AbductionThe control group performed only

the isotonic exercises in their daily rou-tine. The experimental group performedthese exercises in addition to eccentricand concentric strengthening, using theTheraband Elastic Band three times perweek. The Theraband eccentricstrengthening was preceded by the tra-ditional isotonic maintenance routine.1'

The Theraband routine consisted ofexercise in the D2-diagonal pattern ofproprioceptive neuromuscular facilita-tion (PNF) patterns.27 Subjectsattached the fixed end of the elasticband to the wall hooks even with theiliac crest (Fig 4). Standing with theopposite shoulder and side nearest thefixed origin, the subjects faced 900 ineither direction to keep the oppositeshoulder nearest the origin. The dis-

348 Volume 28 * Number 4e 1993

tance between the base of the wallhooks and the nearest foot was 3 ft.The dominant hand was placed on theopposite hip (nearest the origin), simi-lar to the starting position for the D2-flexion pattern (Fig 2). The Therabandlength was 3 ft from the origin to thehand, with no tension or slack in theelastic band.

Subjects performed the D2-flexionpattern concentrically to a position offull abduction, flexion, and externalrotation by stretching the Theraband,paused 1 second, and performed theD2-extension pattern eccentrically byallowing the elastic band to pull thearm slowly back to the starting posi-

tion of adduction/extension/internalrotation. We monitored subjects forcorrect posture during the exercise toensure that all movement occurredonly at the shoulder and that theymaintained a smooth, slow, fluidmotion. Care was taken to ensure thatsubjects did not "cheat" by engagingother muscles of the upper and lowerbody. Subjects performed the repeti-tions in about 10 seconds (3 secondsfor the concentric phase, 2 secondsrest, and 5 seconds for the eccentricphase). They rested for 2 secondsbetween repetitions with the hand atthe opposite hip (Fig 4) and for 1

minute between sets.

Subjects performed three sets ofrepetitions per day. They began with10 repetitions per set during the firstsets of a new resistance. Each sessionadded five more repetitions, as tolerat-ed by the subject, up to 25 repetitions.The resistance of the Theraband iscolor-coded in progressive strengths.The resistance began with light(yellow band) and increased progres-sively in strength (yellow, red, green,and blue) based on the ability of thesubject to properly complete theprescribed sets and repetitions withoutsoreness or perceived excess fatigue.After three sets of 25 were ac-complished, the resistance was

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increased and the repetitionsdecreased to three sets of 10, againprogressively increasing. The goal ofthree sets of 25 repetitions was estab-

lished to ensure that the subjects were

working at a light weight with highrepetitions, thus improving enduranceand aerobic capabilities, while pro-

viding for strength gains. These exer-cises were performed 3 days per weekafter the isotonic routine in the ex-perimental group. We instructed sub-jects to stretch their shoulders on theirown for 5 minutes before and afterexercise.We performed two one-way analy-

ses of covariance on the data to deter-mine if the posttest scores of the twogroups were significantly different,with pretest scores as the covariate.

ResultsAt 60°/s, the experimental group

increased 19.8 ± 7.1% in eccentricposterior rotator cuff strength whilethe control group decreased (-1.6 ±14.8%; (Table 1). Both groupsdecreased in strength at 1800/s (-14.8± 25.3% and -8.1 ± 25.6%, respec-tively). The experimental group wassignificantly stronger following train-

a b

e

c d

9fFig 3.-Isotonic exercises: (a) circumduction; (b) abduction; (c) biceps curls; (d) triceps extensions; (e) standingsupraspinatus; (J) posterior cuff external rotation; (g) horizontal abduction.

350 Volume 280 Number 4 * 1993

ba

Fig 4.-Theraband routine start (a), middle (b), and finish (c).

ing than the control group at 600/s(F(1,9) = 11.75, p = .008), but therewas no significant difference betweengroups at 180°/s (F(1,9) = .20, p =

.66).

DiscussionWhile this study indicated that

Theraband strengthening may increaseeccentric strength in the diagonal pat-tern, it raises further issues and ques-

tions for discussion. Little researchexists regarding Theraband, eccentricfunctional shoulder testing, or

strengthening studies involving pitch-ers. There have been no previous stud-ies regarding the effectiveness ofTheraband strengthening, and there are

very few regarding elastic-band exer-

cise. Most literature provides only sug-

gested exercises.4'525'29'36'38 Many use

elastic tubing exercise as a strengthen-

ing device; however, most do notknow the extent or actual value of itsresistance. Elastic resistance exercisehas not been labeled as being specificto a mode of contraction (ie, isotonicor isokinetic) because of its elasticproperties. There is some question as

to sets, repetitions, and resistance. Itmay be assumed to be isodynamic or

accommodating resistance, because theresistance can be effectively changedby varying the band length or leverarm. No norms or recommendationshave been established. Research isneeded to substantiate claims by prac-titioners regarding both. Therefore,this study provides a basis for muchneeded further research in this area.

Speed and Mode of ContractionThe posterior rotator cuff (decelera-

tor) muscles must contract eccentrical-

Table 1.-Average Eccentric Force of Posterior Rotator Cuff (ft-lb)Experimental Control

600/sPretest 22.7 + 7.4 23.3 + 5.7Posttest 28.2 + 8.1 22.7 ± 4.5% difference 19.8 + 7.1 -1.6 + 14.8

1800/sPretest 31.5 + 8.1 27.5 + 6.9Posttest 27.3 ± 5.9 24.5 + 5.5% difference -14.8 ± 25.3 -8.1 ± 25.6

ly during the deceleration pattern;therefore, we evaluated the extent ofeccentric strengthening of these mus-cles, specific to speed and mode ofcontraction. Both speed and modewere influenced. The strength gain byour subjects was only significant at theslower testing speed, 60°/s, which isstill much slower than the actual angu-lar velocity of the pitching arm(6180°/s).3' Isokinetic technologydoes not allow for such high velocityfunctional testing; therefore, speedprotocols had to be established for thehypotheses of this study.

The two testing speeds, 60 and180°/s, were chosen because they arecommonly used in isokinetic testing ofthe shoulder.'4"9 Different speeds maybe used, but these two speeds seemedto be the limits of accurate testing.Below 60°/s, the speed was very slow,thus increasing muscle fatigue due tothe prolonged eccentric contraction;above 180°/s, the speeds were muchfaster than the subject would havebeen comfortable with, due to thediagonal pattern.

The reasons for the difference insignificance between speeds is uncer-tain. Duncan and associates"3 reportthat eccentric training at higher speedsincreased the tension-generatingcapacity of connective tissue.Hageman et al,19 however, reportinconsistent increases in eccentrictorque production at higher speeds.The increase in eccentric strength ofthe experimental group at the slowerisokinetic testing speed could indicatethat the 600/s may have been morespecific to the strengthening speed,since the strengthening repetitionswere slow and controlled to emphasizethe eccentric contraction. Conversely,the specificity of training principle ofspeed may then lead one to assumethat a faster strengthening speedwould have produced a significantgain at 180°/s, contrary to the slowand controlled motion in this study.

The difference may also be attrib-uted to the order of testing of speedsduring evaluation. Because 600/s wasevaluated first, it may have fatiguedthe decelerator muscles to the point ofnot providing a significant contraction

352 Volume 280* Number 4 * 1993

b ca

at the higher speed for the second test.Future eccentric testing might firstevaluate the faster speeds, followed byslower speeds, or randomize the orderof testing speeds.

The concentric phase of thestrengthening pattern may have alsocontributed to an increase in eccentricstrength. In order to facilitate theeccentric contraction using Therabandin the diagonal pattern, the subjectshad to concentrically contract the pos-

terior rotator cuff to the starting posi-tion (Fig 4). Some authors suggest thatconcentric contractions may be suffi-cient to provide gains in eccentric-strength.34'35 This strength gain, how-ever, may not be specific to the func-tional mode of contraction.

Testing Protocol andDeceleration Patterns

The testing and strengthening pat-tern in this study was an importantissue; however, there was some ques-

tion as to the reliability of this testingposition. This specific eccentric testingposition has never been used inresearch involving the pitching shoul-der. Diagonal patterns testing the con-

centric strength of the pitching shoulderare used on other dynamometers, how-ever.8 10 By combining the literature on

the biomechanics of the decelerationpattern and studies using the diagonaltesting pattern, we developed the sub-ject positioning for testing (Fig 1).

Jobe et a123 used EMG analysis todetermine the contraction of musclesduring the deceleration phase.Electromyographic analysis of themuscles of the posterior rotator cuffduring this deceleration patternstrengthening and testing may beneeded to establish the validity of thetesting position. Through EMG stud-ies, the decelerator muscles can beevaluated for their function as well as

their contraction pattern duringstrengthening or testing.5 This may

lead to a better understanding ofeccentric exercises used to train thedecelerator muscles.

Because no studies were availableon this specific eccentric testing pat-tern, no posterior rotator cuff norms

have been established. This pattern

must be evaluated to establish norms

on baseball pitchers or other throwingathletes to determine adequate levelsof conditioning for competition, or toestablish goals for strength training.This may also lead to the establish-ment of normal ratios for vital ago-

nist/antagonist balance2'8",6"18'21'25'38 ofthe anterior and posterior rotator cuffusing eccentric and concentric con-

tractions. Cook et a18 report muscleasymmetry between rotator cuff mus-

cle groups in baseball players. Normsare reported in regards to internal rota-tion/external rotation in concentrictesting.2 9'10'22 This, however, is notfunctional to both the movement pat-tern or muscular contraction type dur-ing deceleration.

Other studies evaluate isokineticstrength in pitchers at different arm

positions2'6'8 and compare strength topitching velocity.32 33 Most studiesreport a 3:2 concentric internal rota-tion-to-external rotation ratio.2'10'22The functional-diagonal pattern we

used may be used to evaluate anteriorrotator cuff concentric strength specif-ic to acceleration. It can then be usedto correlate the strength with othervariables specific to pitching or throw-ing, or to shoulder injuries.

Injury PreventionThrough Conditioning

The deceleration pattern used inthis study has numerous implicationsregarding shoulder injuries, includingpreventive strengthening and evalua-tion. The strengthening pattern may beused to specifically train the decelera-tors and thereby prevent injury to theposterior rotator cuff. The biomechan-ics of the deceleration pattern as wellas the agonist/antagonist balance are

important in injury prevention.McLeod28 stated that decelerationforces are twice as great as accelera-tion forces and act for a much shortertime, with peak torque reaching 300ft-lb. Biomechanically, the shoulderjoint is "thrown" toward the target inpitching, and has a natural tendency tofollow the ball after release. This can

cause the humeral head to separatefrom the glenoid fossa, due to distrac-tion forces. Only the rotator cuff mus-

cles, joint capsule, and glenohumeralligaments provide stabilization for theshoulder. Unlike the decelerator mus-

cles, capsular and ligamentous tissuecannot be strengthened or tightenedwith resistive exercise. The distractionof the humeral head and glenoid fossamay lead to microtrauma of the rotatorcuff, glenoid labrum, capsule, or liga-ments.3,28 Therefore, strong posteriorrotator cuff muscles must eccentricallycontract to decrease the joint distrac-tion during follow-through and subse-quent injury.' 221'23

Pitchers may experience posteriorshoulder soreness following extensivethrowing. There are many theoriesregarding the cause of this soreness.

Eccentric contractions of the decelera-tors may cause delayed-onset musclesoreness."7'30 Specific eccentric train-ing may enhance muscular recovery

following pitching, thus reducing sore-

ness. This soreness may also be attrib-uted to microtrauma of the shoulder,secondary to muscular weakness or

imbalance.3'28

ConclusionThis study has provided evidence

that Theraband exercise of the posteri-or rotator cuff in the deceleration pat-tern is effective in increasing eccentricstrength at slow speeds, but not at fastspeeds. These findings can be used tosubstantiate some claims of strengthgains using elastic-band exercise, butmuch further research is necessary. Anideal design would include two largerexperimental groups-one group

using isotonic strengthening alone andone using Theraband strengtheningalone, and a larger control group usingno strengthening. This would easily beaccomplished using an untrained sub-ject sample or performing the studyduring the off-season of athletes.However, we were interested in evalu-ating an in-season maintenance pro-

gram of collegiate baseball players.Elastic rubber tubing should also becompared with a more aggressive iso-tonic program.26 Research from differ-ent areas could be tied together andcould benefit throwing athletes in pre-vention, maintenance, and rehabilita-tion of the shoulder.

Journal of Athletic Training 353

AcknowledgmentsWe thank Straton Karratassos,

ATC, Andy Pearson, PT, and JimHambrick, PT, for their input and sup-port. We also thank Coach Ron Polkand Coach Steve Smith for their help.

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354 Volume 280* Number 4 * 1993