Apunts Med Esport. 2015;50(185):29---34

www.apunts/org

ORIGINAL ARTICLE

Effect enduranceexercise in autonomic balance, rating perceivedexertion and blood lactate levels in healthy subjects

Hugo Ce

a Escuela deb Facultad dc LaboratorUniversidad

Received 14Available on

KEYWOAutonomBlood laRating oexertionIntermit

CorrespoE-mail a

http://dx.d1886-6581/

Document downloaded from http://www.apunts.org, day 01/10/2015. This copy is for personal use. Any transmission of this document by any media or format is strictly prohibited.rda-Kohlera,, Yolanda Pullinb, Jorge Cancino-Lpezc

Kinesiologa, Facultad de Medicina, Universidad Mayor, Santiago, Chilee Medicina, Universidad Rafael Landivar, Ciudad de Guatemala, Guatemala

io de Fisiologa Clnica y Funcin Pulmonar, Facultad de Medicina, Escuela de Kinesiologa, Mayor, Santiago, Chile

February 2014; accepted 22 September 2014line 11 November 2014

RDSic balance;ctate;f perceived;tent exercise

AbstractPurpose: The aim of this study was to determinate the changes in the Autonomic Balance,Rating Perceived Exertion (RPE) and blood lactate after continuous versus intermittent exerciseprotocols.Methods: Seven active and healthy male (33 5.1 years) participated in the study. Each subjectperformed two exercise protocols: (i) a continuous exercise at 110% of the lactate threshold(CONT). The CONT protocol consisted in continuous running, and the distance covered was thesame in meters as it was in the intermittent session, and (ii) an intermittent exercise at 100% ofthe Peak Treadmill Velocity (INTT). The protocol consisted of 30 min of 15 s running, interspersedwith 15 s of passive rest. Autonomic balance was assessed through the LF/HF ratio, beforebeginning the exercises, immediately nishing the exercises and 24 h post-exercise; RPE wasevaluated every 5 min in each exercise protocol; and blood lactate was measured immediatelyafter both protocols. Alpha level was set at P .05.Results: Autonomic balance did not show signicant differences between protocols (P = .60).RPE during INTT exercise was signicantly higher than CONT exercise (P = .01). Blood lactatelevels after exercise did not show signicant differences (P = .68). Heart rate variability param-eters in the time domain (mean RR and pNN50) show no statistical differences between bothprotocols pre and 24 h post exercise (P = .24 and P = .61, respectively).

nding author: Tel.: +56 997926208.ddress: hugorck@gmail.com (H. Cerda-Kohler).

oi.org/10.1016/j.apunts.2014.09.001 2014 Consell Catal de lEsport. Generalitat de Catalunya. Published by Elsevier Espaa, S.L.U. All rights reserved.s of continuous and intermittent

30 H. Cerda-Kohler et al.

Conclusions: The data suggest that intermittent exercise is perceived more intense than con-tinuous, although both protocols showed similar internal loads in autonomic balance and bloodlactate levels. 2014 Consell Catal de lEsport. Generalitat de Catalunya. Published by Elsevier Espaa,S.L.U. All rights reserved.

PALABRBalance Lactato Percepcidel esfueEjerciciointermit

conperc

fue E), yrmite7 var

un n un

interotonso rcicio

Introduc

Recovery aafter traintions and individualizexertion (Ran accessibview, bloodevaluate gtraining exanalysis is of the autoa monitoriand time danalysis inratio can bIt has bee

Document downloaded from http://www.apunts.org, day 01/10/2015. This copy is for personal use. Any transmission of this document by any media or format is strictly prohibited.AS CLAVEautonmico;en sangre;n subjetivarzo;

ente

Efectos del ejercicio de resistenciaautonmico, la escala de esfuerzo sujetos sanos

ResumenObjetivo: La nalidad de este estudiopercepcion subjetiva del esfuerzo (PSejercicio aerobico continuo y uno inteMtodos: En el estudio participaron realiz 2 protocolos de ejercicios: a)(CONT); el protocolo CONT consisti emetros igual a la distancia de la sesinla velocidad pico en cinta (INTT). El pintercalados con 15 segundos de descaratio LF/HF antes de comenzar los eje

y a las 24 h de su nalizacin; la RPE se evalactato en sangre se midi inmediatamenten p 0,05.Resultados: El balance autnomo no reej(p = 0,60). La RPE durante el ejercicio INTT(p = 0,01). Los niveles de lactato en sangrLos parmetros de variabilidad de la frecuepNN50) no reejaron diferencias estadsticy a las 24 h del ejercicio (p = 0,24 y p = 0,61Conclusiones: Los datos sugieren que el ejcontinuo, aunque ambos protocolos reejaautnomo y niveles de lactato en sangre. 2014 Consell Catal de lEsport. GeneraS.L.U. Todos los derechos reservados.

tion

fter exercise, that is, return of body homeostasising is important to obtain training adapta-its control may provide useful data for theation of training loads.1 Rating of perceivedPE) allows to monitor training intensity,2 beingle tool for training control. From a metabolic

lactate (production vs removal) can be used tolycolytic activity and to assist with determiningercise intensity3. Heart Rate Variability (HRV)a non-invasive measurement of cardiac controlnomous nervous system,4,5 and can be used asng tool to control training loads.1 Frequencyomain are the most used assessment for HRV

different physiological conditions.5,6 LF/HFe used as a measure of autonomic balance.1,5,7

n reported that HRV indexes are modied by

exercise trendurancemost studie

AlthougLT intensitlate vagal the cardioperformedaerobic exemittent exthese goalsmarily perabout HRV,cise. The aautonomictinuous exintermitten(PTV) in hetinuo e intermitente sobre el balanceibido y los niveles de lactato en sangre en

determinar los cambios en el balance autnomo, la el lactato sanguineo despues de un protocolo dente.ones activos y sanos (33 5,1 anos). Cada sujetoejercicio continuo al 110% del umbral del lactatoa carrera continua, siendo la distancia cubierta enrmitente, y b) un ejercicio intermitente al 100% decolo consisti en 30 min de carrera de 15 segundos,pasivo. El balance autnomo se evalu mediante els, inmediatamente despus de nalizar los mismos,

lu cada 5 min en cada protocolo de ejercicios, y ele tras ambos protocolos. El nivel alfa se estableci

diferencias signicativas entre ambos protocolos fue considerablemente superior al ejercicio CONTe no reejaron diferencias signicativas (p = 0,68).ncia cardiaca en el dominio del tiempo (RR medio yas entre ambos protocolos, con mediciones previas, respectivamente).ercicio intermitente se percibe ms intenso que elron cargas internas similares en cuanto a balance

litat de Catalunya. Publicado por Elsevier Espaa,

aining at different intensities,8 been continuous training of low and moderate intensities thed type of exercise related to HRV.9,10

h low to moderate exercise intensity (close toy) has been proposed systematically to modu-activity,9,10 to obtain complete adaptation invascular system and vagal activity should be

a combination of moderate and high intensityrcise.11,12 Recent studies have shown than inter-ercise may have an important role in achieving,13---15 however, these adaptations are both, pri-ipherally or acute effects and little is known

RPE, and lactate responses to intermittent exer-im of this study is to analyze the response of

balance, RPE and blood lactate levels in con-ercise at 110% of lactate threshold (LT), andt exercise at 100% of Peak treadmill velocityalthy subjects.

Effects of continuous and intermittent endurance exercise in autonomic balance 31

Materials and methods

Subjects

Seven active male subjects with the anthropometric charac-teristics shown in Table 1 were recruited from a private sportcenter and voluntarily agreed to participate in this experi-mental and cross-sectional study. All subjects were healthyand underwent no medical treatment at the moment of theevaluations. Inclusion criteria was that the subjects trainmoderate to high intensity exercises at least 3 times a weekfor at least the last 2 years, regardless of the discipline per-formed, and had no musculoskeletal injuries at the time ofexercise test and training sessions.

Subjects were instructed to fast for at least 3 h beforeexercise test and training sessions, to restrain from ingestingbeverages containing caffeine or alcohol and not to exer-cise during the 24 h prior and before the test and exercisesessions.

Participants were informed of the purpose of the study,the experimental procedures implicated and all the poten-tial risks iparticipantto a routinconformedresearch a

Experime

Peak treadAfter a 10formed an7 km h1 aincreased peak treadity reachedincrementasignicantl(vVO2max)old (LT) wacriteria userate exercontrolled withdrawa

Table 1 shown as

Age (yearHeight (mBody masBody masPeak treaContinuouIntermitteContinuouIntermitteContinuouIntermitte

HRR, hear

the parasympathetic modulation concomitant to an increasein sympathetic activity. The R-R intervals were analyzedby the time domain through the square root of the meansquared successive differences between adjacent R-R inter-vals (rMSSD) which is related to parasympathetic activity.20

For the de3 millisecoindices (rM

The PTVsity. All surandom ord

IntermitteAfter an 8-stretch circThe sessionthe incremspersed wit

ContinuouAfter an 8-

circssioned ine sam

olle

ratets wl mem.ultanin soniten v

meaost nd danalyedicalysito qncy .40 H

ratio

lactalactaood

prev fora st, Ma

peras

usi subrceiv

Document downloaded from http://www.apunts.org, day 01/10/2015. This copy is for personal use. Any transmission of this document by any media or format is strictly prohibited.nvolved before obtaining written consent. Alls were deemed healthy based on their responsee medical screening questionnaire. The study was

to standards for the use of human subjects ofs outlined in the current Declaration of Helsinki.

ntal design

mill velocity (PTV) determination-min warm up at 8 km h1 the subjects per-

incremental test with an initial velocity ofnd a 0% inclination. The treadmill velocity wasevery minute in 1 km h1until exhaustion.16 Themill velocity (PTV) is dened as the nal veloc-

and maintained for one minute for a maximuml test, which is associated with VO2max17 andy correlated with the Maximal Aerobic Speed

(r = 0.90).18 Determination of Lactate Thresh-s conducted through the HRV and following the

ed by Sales et al.19 Briey, during low to mod-cise intensity the heart rate increase is mainlyby the parasympathetic nervous system (PNS)

l, but at higher intensities there is a reduction in

Descriptive characteristic of the subjects. Data ismean S.D.s) 33 5.13) 1.74 0.05s (kg) 82.1 3.8s index (kg/m2) 27.1 0.9dmill velocity (km/h) 15.4 1.4s exercise volume (m) 3857 349nt exercise volume (m) 3857 349s exercise volume (min) 24.53 2.4nt exercise volume (min) 30 0s exercise intensity (%HRR) 71.4 9.3nt exercise intensity (%HRR) 73.4 5.9

t rate reserve.

stretchThe seobtainwas th

Data c

Heart Subjecand al11:00 a

Sima 10-mrate mhas be

R-R24 h p4 Hz aquent and Mtral an(FFT) freque0.15---0LF/HF

Blood Blood lary blas wasdiatelyusing (Roche

RatingRPE wsessionsessionthe petermination of LT, stabilization point lower thannds (ms) was adopted for of the vagal activitySSD) plotted against the absolute training load.

and LT were used to determine exercise inten-bjects completed both exercise sessions in aer.

nt exercise (INTT) at 100% of PTVmin warm-up at 8 km h1, and followed by 5 minuit, the subjects performed intermittent session.

consisted of 30 min at 100% of PTV obtained inental test with a protocol of 15 s of work, inter-h 15 s of passive rest.

s exercise (CONT) at 110% of ATmin warm-up at 8 km h1, and followed by 5 minuit, the subjects performed continuous session.

consisted in continuous running at 110% of LT the incremental test, and the distance coverede in meters as it was in the INTT session.

ction instruments

variabilityere referred to the laboratory during morningasurements were made between 8:00 am and

eous R-R interval recordings were made duringupine rest period using a Polar RS800CX heartor (Polar Electro OY, Kempele, Finland), whichalidated in previous studies.21

sures were obtained pre, immediately post andexercise session. The data were resampled atetrended with a 1st order method for subse-sis in Kubios Software HRV 2.0 (Biosignal Analysis

al Imaging Group, Kuopio, Finland). The spec-s was performed with the Fast Fourier Transformuantify the power spectral density of the low(LF; 0.04---0.15 Hz), and the high frequency (HF;z) bands. Additional calculations included the

to quantify the autonomic balance.

te determinationte values were obtained via a nger prick capil-sample immediately after each exercise protocoliously described.22 Samples were analyzed imme-

whole blood lactate concentration (mmol/L)andard enzymatic lactate analyzer Accutrendnnheim, Germany).

ceived exertion (RPE)quantied every 5 min until the end of theng the CR10 Borg Scale.23 During each exercisejects had a visual layout of Borgs scale to controled intensity.

32 H. Cerda-Kohler et al.

Table 2 Effects of exercise on heart rate variability. Data is shown as mean S.D.P-CONT PT24-CONT P-INTT PT24-INTT P value

Mean RR 947 150 1007 108 976 95 959 74 0.24pNN50 10 9 9 5 10 LF/HF ratio 2 0.6 1.9 0.8 1.9

Statistics

All data is expressed as means SD. As the sample sizewas small, statistical analyzes were realized with non-parametricexercise vatest, Friedcomparisonwas analyzware, La Jo

Results

The anthropresent stuformed arerate variabdifferences

The chaFig. 1A shopre and imCONT: 2.1 7.5 2; p =between pues of autoreected inand INTT rdifferences

Table 3(immediatetocols. RPEthan CONT

Discussio

Our study cautonomicsubjects. Aexternal loences in RP

Relatedinvestigate

Table 3 tion betwmean S.

Blood lactRPE

comparing (50% and 8ing the folresults con

se w in ina

rciseed nost en coermntinuike sponmedxercr moittenity. Nhatshow

betw andintenuld ave g loaminged bardissioncesnd i.5 mie et

wit of f 7.4

of td an rmitortanl at), aO2m

re

Document downloaded from http://www.apunts.org, day 01/10/2015. This copy is for personal use. Any transmission of this document by any media or format is strictly prohibited. tests. Differences between basal and postlues were determined using Wilcoxon paired t-man test and post-analysis with Dunns multiples test. Alpha level was set at p < 0.05. The dataed in GraphPad Prism version 5.0a (GraphPad Soft-lla, CA, USA).

pometric data of the subjects involved in thedy and the characteristics of the exercises per-

presented in Table 1. Effects of exercise on heartility are shown in Table 2, and show no statistical

between both exercise protocols.nges in autonomic balance are shown in Fig. 1.ws signicant differences in LF/HF ratio betweenmediately post exercise in both protocols (P-

0.6; PT-CONT: 9 3; P-INTT: 1.6 0.9; PT-INTT: 0.0001). Fig. 1B compare autonomic balancere and post 24 h exercise sessions. The val-nomic balance post 24 h between both sessions

LF/HF ratio were 1.6 0.7 and 2.0 0.8 (CONTespectively). There are no signicant statistical

between both conditions (p = 0.60). shows the comparison of blood lactate valuesly post exercise) and RPE between exercise pro-

during INTT exercise was signicantly higher exercise (p = 0.01).

n

ompared the effects of two exercise protocols in balance, RPE and blood lactate in male healthylthough both exercise sessions have differentads (intensity), internal loads only show differ-E when the volume is equivalent in both sessions.

to acute autonomic balance, Parekh and Lee8

d the acute response of autonomic balance

Blood lactate values and rating perceived exer-een both exercise protocols. Data is shown as

exercichangepredomto exeobservance pbetwethe intthe co

Unltory reperfortent egreateintermintenscant, w(HRR) % HRR71 9ative This cosions htraininperforsustain

Regtwo sedifferetate awere 5Demarformedat 50%tate oat 90%showeof inteIs impintervaat PTVthe vVPassiveD.

INTT CONT P value

ate 6 1 5.5 1 0.687 0.7 6.1 0.5 0.01*

oxygen in tine resyntet al.26 comhealthy stuergometer 11 12 11 0.61 1 3 2 0.60

aerobic exercise at two different intensities0% of VO2 reserve), and taking the data dur-lowing 30 min at the end of the exercise. Theirrmed their hypothesis that a higher intensityas associated with an increased post-exerciseautonomic balance and showing a sympatheticnce. Our data showed that the acute response

is very similar between the two protocols. Weo signicant differences in acute autonomic bal-exercise (p 0.99; LF/HF = 6.9 3 and 7.5 2),ntinuous and intermittent respectively, although

ittent session was perceived as more intense thanous session.

Parekh and Lee8 and related to cardiorespira-se, in our research the continuous exercise was

on an average of 63% of the PTV, and intermit-ise at 100% of the PTV, which should display adulation of autonomic balance by the SNS ast exercise was conducted at a signicantly higherevertheless, the differences were not signi-

could be because the average heart rate reserveed no signicant differences (mean and SD ofeen continuous and intermittent exercise were

73 5 respectively, p = 0.41), whereby the rel-sity from this point of view was very similar.be justied with the fact that intermittent ses-a rest period interspersed between each intervald, leading to a longer time for exhaustion than

the same exercise continuously, which can beetween 2.5 and 10 min.24

ng to blood lactate levels at the end of thens, these did not show statistically signicant

(p = 0.68) (mean values between continuous lac-ntermittent lactate at the end of the sessionmol/L 1.1 and 6.0 mmol/L 1.2, respectively).

al.24 compared intermittent exercise session per-h 30 s at 100% of the vVO2max and an active pausethe vVO2max, resulting in mean values of lac-

mmol/L, and a continuous exercise performedhe vVO2max until exhaustion, where the lactateaverage of 8.0 mmol/L. In our research the meantent training lactate was lower (6.0 1 mmol/L).t to clarify that Demarie et al.24 used a longer

vVO2max (30 s) compared to our protocol (15 snd they also used an active pause at 50% ofax (30 s), whereas we used a passive rest (15 s).st would allow greater recovery of available

hemoglobin and myoglobin, and phosphocrea-hesis.25 More recent data conducted by Okunopared a continuous and intermittent session in 10dents, where they performed intermittent cycleprotocols at two different intensities with 30 s of

Effects of continuous and intermittent endurance exercise in autonomic balance 33

20A B*

*

4p=0.6

315

HF HF

P-CON

T

Figure 1 post(B). LF/HF, T, prpost interm interHinge, 25th imum

exercise an(CP: powerthe maximobtaining lrespectiveintermittenin compariThis couldresearch aing more tto increase

Concernby Okuno exertion bof 20 poin17.1 (veryrespectivewith the hseen that difcult vsstudy, resp

Finally, the LF/HFproposed between 1autonomiclower thanshowed thVO2 peak cis comparasession. InHRR), the and had anshowing a without sigexercise (pshort and linterval exwas LF/HF24 h and 4tinuous ex(VT2), and

imal restbetwols, F ra

HF raup r

d 1.9lthoterspitten.1, cragencesse pres epite e th

lusi

dingintend simlactaoth p

Document downloaded from http://www.apunts.org, day 01/10/2015. This copy is for personal use. Any transmission of this document by any media or format is strictly prohibited.2

1

0

10LF

/

LF/

5

0

P-CON

T

PT-

CONT

P-INT

T

PT-

INTT

Comparison of autonomic balance between pre and immediately low frequency/high frequency; P-CONT, pre continuous; P-INTittent; PT24-CONT, post 24 h continuous; PT24-INTT, post 24 h

Percentile; Inside Hinge, Median. Whiskers: Minimum and Max

d 30 s of passive pause, one to the critical power output at the lactate threshold) and the other toum intensity of the lactate steady state (MLSS),actate averages of 6.9 mmol/L and 5.1 mmol/L,ly. Our results shows that blood lactate levels int exercise was 6.0 1 mmol/L, being lower

son to exercise at CP, but greater than the MLSS. be interpreted as the intensity used in ourllows greater activation of fast bers, stimulat-he glycolytic metabolism, and thus contributingd production of lactate.ing the RPE, and in the same study conductedet al.,26 they observed the rating of perceivedetween both protocols occupying the Borg scalets. Their results showed that the average was

difcult), and 15.7 (difcult), CP and MSSLly. When comparing the INTT session of our studyigher intensity protocol of Okuno (CP), it can beRPE was felt less intense in our research (very

difcult in Borgs Scale, Okuno et al.,26 and ourectively).autonomic balance values post 24 h, reected in

ratio, has being documented. Hynynen et al.27

that normal values at rest for LF/HF ratio is and 2, where values greater than 2 shows that

balance is modulated mainly by the SNS and if 1 it is modulated mainly by the PNS. Pober et al.10

of maxactiveences protocin LF/Hof LF/ous gro3.4 anours, aand ininterming of 2an avediffereexerciby Jam

Desbecaus

Conc

Our nmore showeblood lar in bat a continuous exercise session of 1 h to 65% ofould modulate the AB toward PNS post 24 h, whichble with our research in the continuous exercise

our study the intensity was similar (63% of thelength thereof was lower (Mean: 24.53 2 min),

average value of 1.9 in the LF/HF ratio post 24 h,modulation toward to PNS in 57% of cases, butnicant differences between pre and 24 h post

0.99). Mourot et al.28 realized a comparison ofong term effects on HRV between continuous andercise session. A parameter that was considered

ratio and made the comparison immediately, 1 h,8 h post exercise session. They compared a con-ercise session at 100% of ventilatory threshold 2

interval training with 1 min of exercise at 100%

could be using exercisloads only salent in boon other fa

Further these ndiHRV analysdeterminatas HR recov

Conict

The authorinterests rePT24

-CONT

P-INT

T

PT24

-INTT

exercise (A) and between pre and post 24 h exercisee intermittent; PT-CONT, post continuous; PT-INTT,mittent. Box: Upper Hinge, 75th Percentile; Lower. Plus sign: Mean. *P < 0.05.

aerobic power (MAP) interspersed with 4 min of at 100% of VT2. They found signicance differ-een pre and immediately post exercise in bothbut no signicant differences in post 24 and 48 htio, compared with basal values. The basal valuestio were 1.0 and 1.2 in the interval and continu-espectively, and 24 h post exercise session were, respectively. These results are very similar tough interval exercise differs in both training loadersed rest. Our data show that LF/HF ratio int exercise had an average value 24 h post train-ompared with the continuous exercise which had

value of 1.7 (p 0.99), showing no signicant in autonomic balance posts 24 h between twootocols, results also consistent for those foundt al.29

the results, they must be interpreted carefullye size of the experimental samples was small.

ons

s suggest that intermittent exercise is perceivedse than continuous, although both protocolsilar internal loads in autonomic balance andte levels. Kinetics of autonomic balance is simi-rotocols immediately and 24 h post exercise, and

ed as a simple and non-invasive tool for monitor-e load in aerobic intermittent exercise. Internalhow differences in RPE when the volume is equiv-th sessions, suggesting that modulation dependsctors than exercise intensity.research is needed to conrm and complementngs, which could incorporate different types ofis, such as time-frequency analysis for thresholdsion, as well as incorporating other variables suchery and its relationship with HRV.

of interest

s declared there is not any potential conict ofgarding this article.

34 H. Cerda-Kohler et al.

Acknowledgement

We would like to thanks the participants for their valuablecooperation.

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