Effect of Branched-Chain Amino Acid Supplementation on Recovery Following Acute Eccentric

15 Pages·2017·2.38 MB·English

nutrients
Article
Effect of Branched-Chain Amino Acid Supplementation
on Recovery Following Acute Eccentric Exercise
TrishaA.VanDusseldorp1,* ,KurtA.Escobar2,KellyE.Johnson3 ,MatthewT.Stratton1,
TerenceMoriarty4,NathanCole4,JamesJ.McCormick4,ChadM.Kerksick5 ,
RogerA.Vaughan6,KarolDokladny7,LenKravitz4andChristineM.Mermier4
1 DepartmentofExerciseScienceandSportManagement,KennesawStateUniversity,Kennesaw,
GA30144,USA;[email protected]
2 DepartmentofKinesiology,CaliforniaStateUniversityLongBeach,LongBeach,CA90840,USA;
[email protected]
3 DepartmentofKinesiology,CoastalCarolinaUniversity,Conway,SC29528,USA;[email protected]
4 DepartmentofHealth,ExerciseandSportsScience,UniversityofNewMexico,Albuquerque,
NM87131,USA;[email protected](T.M.);[email protected](N.C.);[email protected](J.J.M.);
[email protected](L.K.);[email protected](C.M.M.)
5 SchoolofHealthSciences,LindenwoodUniversity,St.Charles,MO63301,USA;[email protected]
6 DepartmentofExerciseScience,CongdonSchoolofHealthSciences,HighPointUniversity,HighPoint,
NC27268,USA;[email protected]
7 DepartmentofInternalMedicine,SchoolofMedicine,UniversityofNewMexico,Albuquerque,
NM87131,USA;[email protected]
* Correspondence:[email protected];Tel.:[phone]
(cid:1)(cid:2)(cid:3)(cid:1)(cid:4)(cid:5)(cid:6)(cid:7)(cid:8)(cid:1)
(cid:1)(cid:2)(cid:3)(cid:4)(cid:5)(cid:6)(cid:7)
Received:17August2018;Accepted:26September2018;Published:1October2018
Abstract: Thisstudyinvestigatedtheeffectofbranched-chainaminoacid(BCAA)supplementation
onrecoveryfromeccentricexercise. TwentymalesingestedeitheraBCAAsupplementorplacebo
(PLCB)priortoandfollowingeccentricexercise. Creatinekinase(CK),verticaljump(VJ),maximal
voluntary isometric contraction (MVIC), jump squat (JS) and perceived soreness were assessed.
Nosignificant(p>0.05)groupbytimeinteractioneffectswereobservedforCK,soreness,MVIC,VJ,
orJS.CKconcentrationswereelevatedabovebaseline(p<0.001)inbothgroupsat4,24,48and72hr,
whileCKwaslower(p=0.02)intheBCAAgroupat48hrcomparedtoPLCB.Sorenessincreased
significantlyfrombaseline(p<0.01)inbothgroupsatalltime-points;however,BCAAsupplemented
individuals reported less soreness (p < 0.01) at the 48 and 72 hr time-points. MVIC force output
returnedtobaselinelevels(p>0.05)at24,48and72hrforBCAAindividuals.Nosignificantdifference
betweengroups(p>0.05)wasdetectedforVJorJS.BCAAsupplementationmaymitigatemuscle
soreness following muscle-damaging exercise. However, when consumed with a diet consisting
of~1.2g/kg/dayprotein,theattenuationofmuscularperformancedecrementsorcorresponding
plasmaCKlevelsarelikelynegligible.
Keywords: BCAA;muscledamage;recovery;supplement;eccentricexercise;sportsnutrition
1. Introduction
Skeletalmuscledamageinducedbyresistance-basedexerciseisknowntopromotemicrodamage
in muscle fibers, which may lead to temporary increased passive tension, delayed onset muscle
soreness(DOMS),decrementsinstrengthandforceproduction,andincreasedeffluxofintramuscular
proteinsintotheblood[1]. Thedegreeofdamageanddiscomfortmaybecompoundedovertime
andpersistchronically,especiallyinindividualsfrequentlyengaginginvigorousexerciseorthose
completinganoverreachingphase[1,2]. Assuch,nutritionalstrategieshavebeenproposedtomitigate
Nutrients2018,10,1389;doi:10.3390/nu10101389 www.mdpi.com/journal/nutrients
Nutrients2018,10,1389 2of15
thenegativeeffectsthatmaybeexperiencedfollowingstrenuousresistanceexercise.Proteinandamino
acidsupplements,includingbranched-chainaminoacids(BCAA),havebeenconsideredapotentially
efficaciousdietaryintervention[3–5]. BCAAs(i.e.,leucine,isoleucineandvaline)aredistinctamong
essential amino acids in that they are extrahepatically metabolized in skeletal muscle [6,7]. It has
beensuggestedthatBCAAsupplementationmayreduceproteindegradationand/ormuscleenzyme
release[2,3,8],decreaseskeletalmuscledamageinresponsetointenseresistanceexercise[9–11],reduce
feelingsofsoreness[12],mitigatecentralfatigue[13,14]andpromotesubsequentrecoveryofmuscle
function[10,15];however,thesefindingsremaininconclusiveatpresent[15–17]. Whileunderlying
mechanismsremainunclear[2,18],BCAAsupplementationisapopularpracticeamongrecreational
exercisersandathletes[8,19,20]andcontinuestogarnersignificantresearchinterest. Forexample,
Howatsonetal.[10]examinedtheimpactof12daysoftwodailydosesof10grams(g)ofBCAAor
placebointrainedmaleswhocompletedaworkoutconsistingof100drop-jumps. Incomparisonto
placebo,plasmacreatinekinase(CK),perceivedsorenessandforceproductionwereallimprovedfor
thefirst24hrwhilesorenessremainedsignificantlylowerupto48hrafterdamagingexerciseinthe
BCAAsupplementedgroup. Nodifferenceswerenotedforverticaljump. Inaddition, Sharpand
colleagues[11]supplementedeightrecreationallyactivemenwitheitheraplaceboor6gofBCAAfor
threeweeksandreportedareductioninCKlevels12and36hraftercompletingtwodaysofintense
resistanceexercise. Jackmanandinvestigators[15]reportedthatcomparedtoplacebotreatment,29.2g
ofBCAAperdayresultedindecreasedDOMSat48and72hrin24non-resistancetrainedmalesafter
unilateraleccentricexercise. However,nodifferencesinpercentchangeforelectricallystimulated
maximalisometricforceofthequadriceps,plasmaCK,myoglobinandinterleukin-6responsebetween
groupspost-exercisewereobserved. Further,Foureetal.[16]foundthatmusclesorenessandMVICin
26recreationallyactivemenwerenotaffectedby0.1g/kgofBCAAingestedpre-andpost-damaging
neuromuscularelectrostimulationexercise.
ResultssurroundingtheabilityofBCAAstofavorablyimpactrecoveryfromdamagingexercise
are mixed. While a multitude of reasons for these inconsistencies exist, controlling for dietary
protein intake seems to be an area that previous research has not adequately considered. In this
respect, Howatson et al. [10] reported significant improvements in force production, circulating
CK levels and perceived soreness, but daily protein intake was not controlled which could have
resulted in discrepancies in overall amino acid intake. Moreover, Sharp and colleagues [11] also
reportedpositiveoutcomesforBCAAsupplementation,butindividualswhowereconsumingadaily
proteinintakeabovetherecommendeddailyallowance(0.8g/kg/day)wereexcludedfromthestudy.
Foureetal.[16]reportednodifferencebetweenBCAAandplaceboinsorenessandforceproduction.
Ofnote,participantsintheFoureetal. investigationwhoweresupplementedwithBCAAsconsumed
significantlygreaterquantitiesofdailyproteinonsupplementationdays, 1.5g/kg/day, whilethe
proteinintakefortheplacebogroupaveraged1.07g/kg/day. Finally,Jackmanetal.[15]reportedonly
reductionsinsorenesswhenindividualsweresupplementedwith29.2gofBCAAsperdayoraplacebo
afteradamagingboutofexercise. Notably,dailyproteinintakeintheJackmanstudywascontrolledat
1.5g/kg/dayforsubjectsinbothBCAAandplacebogroupswhichmayhaveinfluencedtheirfinal
outcomes. Therefore,itseemspossiblethatwhenBCAAsupplementationisprovidedwhiledaily
proteinintakeisnotalreadyatrecommendedlevels[21,22],thepotentialforBCAAadministrationto
affordanyadditionalimpactmaybeimproved.
Asitstands,theinconsistenciesdocumentedinnumerousinvestigationsfollowingdamaging
resistanceexerciseandsubsequentrecoverypreventsanyconclusiveinferencesregardingtheefficacy
ofBCAAsupplementation. Curiously,BCAAsupplementationhasstillbeenassociatedwithreduced
perceivedsorenessfollowingintenseresistanceexercise[5,15,23],thoughmechanismsexplainingthe
relationship between BCAA ingestion and perception of muscle soreness are not well established.
Moreover,currentevidencesuggeststheattenuationofDOMS[5,15,24],aswellaseffluxofbiochemical
markersofmuscledamageinindividualssupplementingwithBCAA[5,10,11],donotnecessarilyoccur
withaconcomitantenhancementofmusclefunctionrecovery[4,5,15]. Addingtothiscomplexityare
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thediscrepanciesintrainingstateofstudyparticipants,damagingexerciseprotocolsandoverallprotein
intakeemployedwithinthelimitednumberofstudiescompleted. Finally,thepopulationmostaptto
supplementwithBCAAtoattenuatethenegativeeffectsofintenseresistanceexerciseareresistance
trainingindividualswhoarelikelyalreadyingestingamoderateproteinintake(1.4–2.0g/kg/day)[21],
thuspotentiallymakingexogenousBCAAconsumptionsuperfluous. Forthesereasons,thepresent
studyaimedtoinvestigatetheeffectsofBCAAsupplementationonmarkersofmuscledamageand
recoveryofmusclefunctioninresistancetrainedmaleswhileadheringtoaproteinintakeslightly
lowerthantherecommendedrangeforresistancetrainingindividuals.
2. MaterialsandMethods
2.1. Participants
Twenty young, resistance-trained (RT) males (age 22.3 ± 1.5 year, height 175.4 ± 6.7 cm and
body mass 86.4 ± 15.6 kg) were recruited for the study. The present study was approved by the
institution’sHumanResearchReviewCommittee. Participantsweremadeawareofallprocedures’
risks and benefits, gave written consent and completed health history, diet history and physical
activity questionnaires. All participants had several years (5.3 ± 2.5 year) of resistance exercise
trainingexperience,withanaverageself-reportedtrainingtimeof7.3±2.1hrperweek. Participants
wereexcludediftheywereconsumingcreatine(withinthepastsixmonths)andcertainmedications
(non-steroidalanti-inflammatoryorsteroidaldrugs). Individualsconsumingproteinsupplements
(e.g.,whey,casein)wereaskedtorefrainfromtakingthesesupplementsfollowingenrollmentinto
thestudy. Individualsutilizingtreatmentssuchascryotherapyormassage,pastorcurrentsmokers,
thosewithoutatleastoneyearofcurrentresistancetrainingexperienceandparticipantswhohad
completedhighvolumesofunaccustomedlower-bodyresistance-basedexerciseinthelastsixmonths
(tocontrolfortherepeatedbouteffect)[9]werealsoexcludedfromthestudy. Further,allincluded
participantsrefrainedfromexerciseandalcoholconsumption48hrpriortotestingandthroughout
theentiretestingperiodandcaffeine12hrpriortoeachvisit. Participantcharacteristicsareshownin
Table1.
Table1.Participantcharacteristics.
Characteristic BCAA PLCB
Participant# 10 10
Age(yr) 23.0±1.2 21.5±1.5
Height(cm) 177.6±7.1 173.2±6.2
BodyMass(kg) 86.6±15.2 86.2±16.8
BodyFat% 12.3±3.8 11.7±4.3
1RMSquat(kg) 154.8±31.7 155.0±32.0
RTExperience(yr) 5.6±2.3 5.0±1.9
RTExperience(hrs/week) 7.00±2.30 7.65±2.05
ProteinIntake(g/kg/d) 1.29±0.12 1.25±0.09
AverageCalorieIntake(kcal) 2555±324 2638±309
Allvaluesaremean±SD.#=numberofparticipants,yr=years,cm=centimeters,kg=kilograms,1RM=one
repetitionmaximum,RT=resistancetraining,BCAA=branched-chainaminoacid,PLCB=placebo,g/kg/d=
grams/kilogram/dayduringstudyenrollment,kcal=calorieintakeperdayduringstudyenrollment,hrs/week=
hoursperweek.
2.2. ExperimentalDesign
Usingarandomized,double-blind,placebo-controlledresearchdesign,participantswereenrolled
into either a BCAA (MusclePharm BCAA 3:1:2 watermelon powder) or PLCB group (color and
flavor matched maltodextrin) and performed one experimental muscle-damaging exercise trial.
Allparticipantswerethoroughlyfamiliarizedwiththestudydesign;specificallythedietandphysical
activity log requirements, timing and procedures of blood collection, 1RM protocol, performance
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Nutrients 2018, 10, x FOR PEER REVIEW 4 of 15
measures(i.e.,verticaljump(VJ),maximalvoluntaryisometriccontraction(MVIC),jumpsquat(JS))
measures (i.e., vertical jump (VJ), maximal voluntary isometric contraction (MVIC), jump squat (JS))
andsupplementationregimen. Figure1depictstheoverallstudydesign.
and supplementation regimen. Figure 1 depicts the overall study design.

Figure 1. Experimental design overview. Participants were supplemented for 8 days with either
Figure 1. Experimental design overview. Participants were supplemented for 8 days with either
BCAAorplacebofollowingbaselineassessment. Participantsreturnedtothelab96hrfollowing
BCAA or placebo following baseline assessment. Participants returned to the lab 96 hr following
baselineassessment.
baseline assessment.
2.3. BaselineTesting: Enrollment,1RM,FamiliarizationandDietaryCounseling
2.3. Baseline Testing: Enrollment, 1RM, Familiarization and Dietary Counseling
Onthedayofbaselinetesting,followingconsentanddeterminationofinvolvement,participants
first hOand tthhee dirayh eoifg bhatsealninde bteosdtiyngm, faoslslomweinagsu croendseanntd antdhe diretberomdyinacotimonp oofs iintivoonlvaesmseesnset,d paurstiincigpathnets
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fsokllionwfoeldd bteychSnmiqituhem. Paacrhtiinciep1aRntMs wasesrees stmheenn ta.sFkoedll otwo icnogm1pRlMetea ass seeslsfm-seenletc,tpeadr ttiecnip-manintsuwtee wreaarmsk-eudp
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paenrdfo 4rm0%an 1cReMdu JrSin pgedrfaotarmcoalnleccet iionn o.rTdeesrt- rtoet eeslitmreinliaabtei laitnyyw laesardneitnegrm efifneecdtsf oorna tlelspte prfeorrfmoramnacencvea rdiaubrilensg
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irnetleiravbeilnittyio hnass[ 2b5e]e.nF sohlloowwnin tog bthee escsoemnptilaelt fioorn eoxfp1eRriMmeanstsaels ssemnesnittivaintyd tfoa mnuiltirairtiiozantailo inntoefrpveenrftoiormnsa [n2c5e].
aFsosellsoswmienngt st,hpe acrtoimcippalenttisonw eorfe 1cRoMun saeslseedssomnesnut papnledm feanmtailtiiaorniz,adtiioenta royf rpeqerufiorremmaennctes, aasnsdesdsmieteanrtys,
tpraacrktiicnigp.aPnatsr tiwciepraen tcsowunerseelaesdk eodnt osrueptuprlnem96enhtratlaiotenr, todiceotamryp lerteeqtuhieremmuesnctlse, daanmda gdiinegtaprryo ttorcaoclk.ing.
Participants were asked to return 96 hr later to complete the muscle damaging protocol.
2.4. AnthropometricMeasurements
2.4. Anthropometric Measurements
Measurements of height, body mass and body fat percentage were obtained to characterize
the paMrteiacsipuarnemts.enBtso dofy hmeiagshst,w baosdym meaassusr aedndv biaodayT faanti ptaerecleencttraognei cwsecrael oeb(tMaiondedel t#o3 c1h0a1r,aActrelriinzget othne
Hpeairgtihctisp,aInLt,s.U BSoAd)y tmoathsse wneaas rmeseta0s.u1rekdg .viTaw ao Tsakniintafo elldecmtreoansiuc rsecmalee n(Mtsoodnelt h#e31r0ig1h, Atsrildinegotofnt hHeebigohdtys,
wILe,r eUoSbAt)a tion ethdef rnoemarethstr e0e.1s kitge.s T(wchoe sskt,inabfodlodm meenasaunrdemtheignhts) oinn stherei arilgfhats hsiidoen obfy ththe ebosadmy ewienrvee osbtitgaaintoerd
uftriolimzi nthgrLeea nsigteesC (achliepsetr, sa(bCdaommbernid agnedS tchiiegnhti)fi inc Isnedriuasl tfraisehs,ioCna mbyb trhideg sea,mMeD in,vUeSsAtig).aStokrin uftoilldizitnhgic kLnanesgse
wCaaslibpaesres d(Coanmtbhreidagvee rSacgieenotfifitch eIntdwuosttrriieasl,s .CaIfmthberidtwgeo, sMkiDn,f oUldSAm).e Saksuinrfeomlde nthtsicfkonreassp waratsic bualasreds ioten
vtahrei eadvberyamgeo roef tthhaen tw0.5o mtriialllism. Ieft ethrse (tmwmo )s,kthinefotelcdh mnieciaasnuroebmtaeinnetsd faort hai rpdamrtiecausluarre smiteen vtaarnidedt hbeym meoarne
vtahlaune 0o.f5t hmeiltlwimoectleorsse (smtmme),a tshuer etmecehnntisciwanas oubsteadin.eBdo ad ythdiredn smityeawsuarsetmheenntc aanlcdu ltahtee dmaecacno rvdailnuge toof tthhee
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metahlnesic. Cmuarkreen-utlpy ,nofo pooupr uplaatritoincipspanectsifi cc-oenqsuisatteidon otfo seisxttimeeant eCpaeurccaesnitanb odanydf aftofuorr HHiissppaanniiccs emxaisletss..
TChuerrreefonrtely,,t hneoS irpioepquulaattiioonn wsapsecuisfiecd-efqouraatlilopna rttoic iepsatnimtsa.te percent body fat for Hispanics exists.
Therefore, the Siri equation was used for all participants.
Nutrients2018,10,1389 5of15
2.5. One-RepetitionMaximum(1RM)
Smith machine (Pro-Elite Strength Systems, Salt Lake City, UT, USA) back squat 1RM was
determinedaccordingtomethodspreviouslydescribed[28]. Followingaten-minutestandardized,
dynamicwarm-up,eachparticipantfirstperformedawarm-upsetof8–10repetitionsatalight-weight
(∼50%oftheirestimated(est)1RM).Asecondwarm-upconsistedofasetof3–5repetitionswitha
moderateweight(∼75%of1RM )andathirdwarm-upincluded1–3repetitionswithaheavyweight
est
(∼90%of1RM ). Afterthewarm-up,eachparticipant’s1RMwastestedbyincreasingtheloadduring
est
consecutivetrialsuntiltheparticipantswereunabletoperformaproperliftusingcorrecttechnique
(90degreesofkneeflexion). The1RMtestwasdeterminedby4–6setsofonerepetition,with3–5min
ofrestbetweenattempts. Spotterswerepresenttoprovideverbalencouragementandspottingto
ensuresafetyoftheparticipants.
2.6. Supplementation,DietandDietTracking
Participantsingested0.22g/kg/dayofBCAA(MusclePharm,Denver,CO;7.16g=3gleucine,1g
isoleucine,2gvaline)ormaltodextrin(PLCB)indry-powderformmixedwithwater(~175–350mL)for
atotalof8daysfollowingbaselineassessment. Thesupplementswereseparatedintoonemorningand
oneeveningdoseperday. Onthefifthdayofsupplementation,participantsreturnedtothelaboratory
andcompletedthemuscle-damagingsquat-exerciseprotocol. Participantswereinstructedtoconsume
theirsupplementpriortocompletingtheexercisevisitaswellasfollow-upvisits. Aresearchteam
member provided each participant with specific verbal and written directions and procedures for
reportingadetaileddietaryintake,includinginformationonhowtorecordportionsusinghousehold
measures,preparationtechniqueandnutrientcontentdescriptors(e.g.,reduced-fat,light). During
theentireexperimentalperiod(8days),participantsrecordedtheirfoodintakeusingapaperfood
log and were instructed, if needed, by a registered dietician on how to achieve a protein intake
of 1.2g/kg/day of body mass. Further, participants were instructed to follow their normal total
calorie intake throughout the duration of the study. Participant’s dietary logs were then entered
into MyFitnessPal (Under Armour, Baltimore, MD, USA) in order to calculate macronutrient and
calorieintake.
2.7. ExperimentalProtocol(MuscleDamagingExerciseVisit)
Participantswereaskedtoreturntothelaboratory96hrfollowingbaselinetestingtoundergoa
muscledamagingexerciseprotocol. Participant’sdietarylogswerecheckedforproteincompliance
uponarrival,followedbyapre-exercisebloodcollection,ratingofperceivedsoreness,andassessments
of VJ, MVIC, and 40% 1RM jump squat. Participants then completed the muscle-damaging squat
exerciseprotocol. Followingcompletionoftheexerciseprotocol,participantsratedtheircurrentstate
ofsorenessandcompletedallmeasuresofexercise-performanceimmediatelypost-exercise(IPE),1,2,4,
24,48and72hrpost-squatexercise. Participant’sbloodwascollected4,24,48and72hrpost-exercise.
Thesametrainedresearcherwasusedforthecollectionofeachparticipant’sperformancemeasures.
2.8. MuscleDamagingProtocol
A standardized bout of resistance exercise involving ten sets of eight repetitions at 70% 1RM
squatsusingaSmithmachine(Pro-EliteStrengthSystems,SaltLakeCity,UT)wascompletedbyall
participants. Eachrepetitionthroughoutthesquatprotocolconsistedofafour-secondloweringand
aone-secondraisingoftheloadmonitoredbyametronomeandspotter. Astopwatchwasstarted
followingthelastrepetitionofeachsetandparticipantsweregiventhreeminutesofrestbetween
allsquatsets. Followingcompletionofthesquatprotocol,participantsthencompletedfivesetsof
20 consecutive (10 each leg) body-weight split jump repetitions with two minutes of rest between
eachset.
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2.9. MarkersofMusclePerformanceandSoreness
2.9.1. VerticalJump
Maximum countermovement VJ was assessed using a Vertec device (Perform Better,
WestWarwick,RI,USA).Participantswereinstructedtostandwiththeirfeetflatandshoulder-width
apartonthegrounddirectlybeneaththeVertec.Participantsweretheninstructedtoreachupashighas
possiblewithasinglearmtomeasurestandingreachheight,definedastheheightofthehighestVertec
vaneaparticipantcouldreach. Participantswerethenaskedtocompleteacountermovementjump
usingbothfeet,whilereachinguptotouchthehighestreachablevane. Eachparticipant’sstanding
reachheightwasthensubtractedfromthehighestvanetouchedafterthecountermovementjump.
Participantswereallowedthreejumps,withthehighestjumprecordedandusedforstatisticalanalysis.
2.9.2. MaximalVoluntaryIsometricContraction
Maximumvoluntaryisometric(MVIC)strengthofquadricepsofthedominantlimbwasmeasured
byadynamometer(BiodexMedicalSystems,System4,Shirley,NY,USA).Participantssatupright
withthechair’sbackrestinclinedto85◦,withtheirkneeplacedin120◦ offlexion(legflexionangleof
60◦ belowthehorizontalplane)[29]. Theaxis(i.e.,lateralepicondyleofthefemur)ofthekneewas
alignedwiththerotationalaxisofthedynamometer. Forthetest,participantswereaskedtoperforma
MVICofthequadricepsmusclesforfivesecondsandthenrestforoneminute. Participantscompleted
thiscyclethreetimesandthepeaktorquevalue(newton-meters)wasrecorded.
2.9.3. JumpSquat
Jumpsquatpeakpower(PP)wasdeterminedbytakingthebetteroftwomaximaleffortJSat
40%ofeachparticipant’s1RMwithoneminuteofrest. AllJSwereperformedusingaSmithsquat
rack(Pro-EliteStrengthSystems,SaltLakeCity,UT,USA).Thecountermovementdepthduringthe
JSwasself-selectedaspreviouslydescribed[30,31]. DuringtheJS,subjectswereaskedtoholdabar
acrosstheirshouldersandkeepconstantdownwardpressureonthebarsothatitwouldnotmove
independentlyofthebody. PowerproductionwasdeterminedviaaTendoPowerAnalyzer(TENDO
PSA310;Irmo,SC,USA).
2.9.4. PerceivedSoreness
Participantswereaskedtoevaluatetheirperceivedlevelofmusclesorenessusingavisualanalog
scale. Sorenesswasassessedalonga10cmscale(0cm=nosoreness,10cm=extremesoreness)for
each time point (pre-exercise, IPE, 1, 2, 4, 24, 48 and 72 hr post-squat exercise) by drawing a line
perpendiculartothecontinuumlineextendingfrom0to10cm. Sorenesswasevaluatedbymeasuring
thedistanceofeachmarkfrom0androundeduptothenearestone-tenthofacentimeter[11].
2.10. BloodSamplingandAnalysis
Venousbloodwascollectedpre-squatexercise,4,24,48and72hrpost-exerciseforthecollection
of plasma. As an indirect marker of muscle damage, plasma concentrations of creatine kinase
(CK) were determined in duplicate using an enzymatic assay (Pointe Scientific, Canton, MI, USA)
and a spectrophotometer (Beckman Coulter, DU-520, Fullerton, CA, USA) at a wavelength of
340nanometers(nm).
2.11. StatisticalAnalysis
Statistical tests were conducted in R (version: 3.2.2; R Foundation for Statistical Computing;
Vienna,Austria)usingthe‘afex’package(version0.16-1). UsingMVICdatagenerated,apost-hoc
poweranalysiswascompleted. Anestimatedeffect(d)oftheinteractioneffectrevealedamoderate
effectof0.61. Atasamplesizeof10participantspergroupanddeltaresponsesforboththePLAand
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BCAAgroupatthe24hrpost-exercisetime-pointresultedinastatisticalpowerof0.523. Separate
mixed-effects (within-between) factorial ANOVAs (group × time) were used to assess the main and
mixed-effects(within-between)factorialANOVAs(group×time)wereusedtoassessthemainand
interaction effects for each reported dependent variable. Post-hoc pairwise comparisons were then
interactioneffectsforeachreporteddependentvariable.Post-hocpairwisecomparisonswerethenused
used to investigate group differences across individual time-points with the Bonferroni adjustment
toinvestigategroupdifferencesacrossindividualtime-pointswiththeBonferroniadjustmentapplied
applied to correct for multiple comparisons. ANOVA models were evaluated for compliance with
tocorrectformultiplecomparisons. ANOVAmodelswereevaluatedforcompliancewithunderlying
underlying model assumptions. Assumptions of sphericity were tested using Mauchly's test of
modelassumptions. AssumptionsofsphericityweretestedusingMauchly’stestofsphericityand
sphericity and violations were corrected using the Greenhouse-Geisser correction factor. Unpaired t-
violationswerecorrectedusingtheGreenhouse-Geissercorrectionfactor. Unpairedt-testswereused
tests were used to determine differences in years of previous resistance training experience, body
todeterminedifferencesinyearsofpreviousresistancetrainingexperience,bodymass,averagestudy
mass, average study protein and calorie intake, and 1RM back squat for BCAA and PLCB groups.
protein and calorie intake, and 1RM back squat for BCAA and PLCB groups. The threshold for
The threshold for statistical significance was set a priori at p ≤ 0.05 for all analyses.
statisticalsignificancewassetaprioriatp≤0.05forallanalyses.
3. Results
3. Results
No significant differences in previous resistance training experience (p = 0.55), 1RM back squat
Nosignificantdifferencesinpreviousresistancetrainingexperience(p=0.55),1RMbacksquat
(p = 0.80) and body mass (p = 0.95) were found at baseline between groups. Further, there were no
(p=0.80)andbodymass(p=0.95)werefoundatbaselinebetweengroups. Further,therewereno
significant differences in protein intake (g/kg/day; p = 0.42) and total calories consumed per day (p =
significant differences in protein intake (g/kg/day; p = 0.42) and total calories consumed per day
0.57). All subjects successfully completed the 80 eccentric squats and 100 body-weight split jumps (50
(p=0.57). Allsubjectssuccessfullycompletedthe80eccentricsquatsand100body-weightsplitjumps
each leg). Four individuals (two from each group) decreased the weight by 10 lbs. (~4.55 kg) in order
(50 each leg). Four individuals (two from each group) decreased the weight by 10 lbs. (~4.55 kg)
to complete the eccentric squat exercise protocol (n = 2: set 6; n = 1: set 8; n = 1: set 9). All performance
in order to complete the eccentric squat exercise protocol (n = 2: set 6; n = 1: set 8; n = 1: set 9).
measures (VJ, JS, MVIC), soreness ratings, and creatine kinase showed time effects (p < 0.05) for both
Allperformancemeasures(VJ,JS,MVIC),sorenessratings,andcreatinekinaseshowedtimeeffects
PLCB and BCAA groups indicating that the eccentric exercise protocol effectively induced muscle
(p<0.05)forbothPLCBandBCAAgroupsindicatingthattheeccentricexerciseprotocoleffectively
damage.
inducedmuscledamage.
3.1. Muscular Performance: Vertical Jump
3.1. MuscularPerformance: VerticalJump
Both groups demonstrated similar (p > 0.05) VJ height prior to the eccentric exercise protocol
Bothgroupsdemonstratedsimilar(p>0.05)VJheightpriortotheeccentricexerciseprotocol
(pre-exercise) (BCAA = 68.71 ± 2.90 cm; PLCB = 69.60 ± 5.87 cm). Vertical jump height was significantly
(pre-exercise)(BCAA=68.71±2.90cm;PLCB=69.60±5.87cm).Verticaljumpheightwassignificantly
lower for both BCAA and PLCB groups IPE, 1, 2, 4, 24 and 48 hr post-eccentric exercise (p < 0.05);
lowerforbothBCAAandPLCBgroupsIPE,1, 2, 4, 24and48hrpost-eccentricexercise(p<0.05);
however, there were no group or interaction effects for vertical jump performance (Figure 2).
however,therewerenogrouporinteractioneffectsforverticaljumpperformance(Figure2).
70
BCAA
*
)m 65 * PLCB
t(c 60 * * *
h *
g
ie 55
H
p
m 50
u
J
45
40
Pre-exercise IPE 1 H R 2 H R 4 H R 24 H R 48 H R 72 H R

Figure2.Mean(±standarddeviation)jumpheight(cm;centimeters)pre-eccentricexercise,immediate
Figure 2. Mean (± standard deviation) jump height (cm; centimeters) pre-eccentric exercise,
post (IPE), 1, 2, 4, 24, 48 and 72 hours (HR) for resistance trained men supplementing with
immediate post (IPE), 1, 2, 4, 24, 48 and 72 hours (HR) for resistance trained men supplementing with
branched-chain amino acids (BCAA) or placebo (PLCB) (n = 20). * = significantly different from
branched-chain amino acids (BCAA) or placebo (PLCB) (n = 20). * = significantly different from pre-
pre-exercise(p<0.05)forbothBCAAandPLCB.
exercise (p < 0.05) for both BCAA and PLCB.
3.2. MuscularPerformance: MaximalVoluntaryIsometricContraction
3.2. Muscular Performance: Maximal Voluntary Isometric Contraction
Bothgroupsdemonstratedsimilar(p>0.05)forceoutputpriortotheeccentricexerciseprotocol
Both groups demonstrated similar (p > 0.05) force output prior to the eccentric exercise protocol
(pre-exercise)(BCAA=305.3±89.7;PLCB=279.7±59.9Nm(Newton-meters)). Maximalvoluntary
(pre-exercise) (BCAA = 305.3 ± 89.7; PLCB = 279.7 ± 59.9 Nm (Newton-meters)). Maximal voluntary
isometricforceoutputwassignificantlyloweratallpost-exercisetimepointsforthePLCBgroup,while
isometric force output was significantly lower at all post-exercise time points for the PLCB group,
theBCAAgrouponlydisplayedsignificantlylowervaluesIPE,1,2and4hrpost-eccentricexercise
while the BCAA group only displayed significantly lower values IPE, 1, 2 and 4 hr post-eccentric
exercise (p < 0.05). Force output was not significantly different from baseline measures at 24 hr (p =
0.18; BCAA: 270.8 ± 68.8 Nm), 48 hr (p = 0.11; BCAA: 271.4 ± 45.8 Nm), or 72 hr (p = 0.21; BCAA: 295.5
Nutrients2018,10,1389 8of15
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Nutrients 2018, 10, x FOR PEER REVIEW 8 of 15
(±p 7<7.01. 0N5m).)F oarncde nouo tspiugtnwifiacsannto tgsriogunpifi-bcyan-ttilmyed ieffffeercetn wtfaros mobbsaesrevleinde amt aenasyu oref sthaet 2t4imher-(ppo=in0ts.1 (8p; B> C0A.0A5):
±(2F 77i0g7.u8.1r ±eN 36m)8.). 8 aNndm n),o4 s8ighnri(fpic=an0t. 1g1r;oBuCpA-bAy:-t2i7m1e.4 e±ffe4c5t. 8wNasm o)b,soerr7v2edh ra(tp a=ny0 .o21f ;thBeC AtimA:e-2p9o5.i5nt±s (7p7 >.1 0N.0m5))
(aFnidgunroe s3i)g. n ificantgroup-by-timeeffectwasobservedatanyofthetime-points(p>0.05)(Figure3).
n
onitco
liittttIsrercrcoayooaunnVCm llitttIsrercraoayooaunnVCm(t-t)seeeronNwm(t-t)seeeronNwm122334122334505050505050000000000000 ^*^* ^*^* ^*^* ^*^* ** ** ** BPBPLLCCCCAABBAA
ilaxamMiaxmM PPr1r1ee-0-0ee00xxeerrcciissee IIPPEE 11 HHRR 22 HHRR 44 HHRR 2244 HHRR 4488 HHRR7722 HHRR

Figure 3. Mean (± standard deviation) force production (Newton-meters) pre-eccentric exercise,
FiFmiiggmuurereed i33a..t eM Mpeoeasantn ( I((P±±E s)st, at1an,n d2d,a a4rdr, d2 4dd,e 4evv8i aiaatnitoidon n7) )2f fhoororcuceer sp p(rHroodRdu)u cfcottirioo rnne s((iNsNteaewnwctteoo ntnr--ammineeetteder rsms)) eppnr reseu--eepccpcceleennmttrreiicnc teienxxgeer rwcciiisstehe,,
ibimmrammnecehddeiiaadtt-eec hppaooisnstt (aI(mPIPEiEn),)o ,1 a,1 c2,i,2d 4,s, 4 2(,B42,C 44A,8 A4a8n) daon r7 d2p lh7a2oceuhbroso u ((HrPsLR(C)H fBRo)r ) (rnfeo s=ri s2rte0as)n.i sc*te a= tn rscaieginnteridfai icmnaenedtnl yms udepinfpfesleurmepneptn lfetrimonmgen wptiirntehg-
bwexriaetnhrccbihsreead n(p-cc h<h ea0di.n0-c 5ah)m afoiinnr oaP mLaCciniBdo.s ^a( cB=iCd ssiAg(AnBiC)f ioAcraA np)tllaoycr edpbifloaf ec(rPeebLnoCt (BfPr)oL (mCn B=p) r2(e0n-)e.=x *e2 r=0c )si.sige* n=(pifs i<icg a0nn.0itfi5lyc) a fdnoirtfl fyBeCrdeAinfftAe fr.r eonmt fprorme-
epxreer-ecxiseer c(pis e< (0p.0<5)0 f.0o5r )PfLoCrPBL. ^C =B .sˆig=nsifiigcnainfitclya ndtilfyfedriefnfetr fernotmfr pomre-perxee-recxiseerc (ips e< (0p.0<50) .f0o5r) BfoCrABAC.A A.
33..33.. MMuussccuullaarr PPeerrffoorrmmaannccee:: JJuummpp SSqquuaatt
3.3. Muscular Performance: Jump Squat
BBootthh ggrorouupps sdedmemonosntrsattreadte sdimsiilmari l(apr > (0p.05>) p0e.0ak5) popweaekr opuotpwuetr aso mutepausturaesd bmye tahseu 4re0d% 1bRyMt hJSe
Both groups demonstrated similar (p > 0.05) peak power output as measured by the 40% 1RM JS
p40ri%or 1toR Mthe JeSccpernitorric teoxetrhceisee cpcreonttorciocl e(pxererc-eisxeerpcirsoet)o (cBoClA(pAr e=- e1x3e9r2c.i9s e±) 3(4B4C.1A; PALC=B 1=3 91423.99.1± ± 324740..15;
prior to the eccentric exercise protocol (pre-exercise) (BCAA = 1392.9 ± 344.1; PLCB = 1439.1 ± 270.5
wPLaCttBs).= P1e4a3k9 .p1o±we2r7 0o.u5twpuatt tws)a.sP seiagknpifoicwanertlyo ulotpwuetrw foars bsiogtnhi fiBcCaAnAtly alnodw PerLCfoBr bgorothupBsC IAPAE, a1n, d2, P4L, C24B,
watts). Peak power output was significantly lower for both BCAA and PLCB groups IPE, 1, 2, 4, 24,
4g8ro aunpds 7I2P hEr, f1o,ll2o,w4,in2g4 ,e4cc8eanntrdic7 e2xherrcfiosell (opw <i n0.g05e)c; cheonwtreicveerx, etrhceirsee w(per<e 0n.o05 g)r;ohuopw oerv ienrt,etrhaecrtieown eefrfeecntos
48 and 72 hr following eccentric exercise (p < 0.05); however, there were no group or interaction effects
fgorro uJSp poerrfinortemraacntcioe n(Feifgfuecrtes 4f)o.r JSperformance(Figure4).
for JS performance (Figure 4).
2000
BCAA
2000
t(tt)saaw t(tt)saaquw 11111572570550500000 ** ** ** ** ** ** ** BPPLLCCCABBA
uS
pSqm Jupm 111020050000
u 750
J
750
500
PPr5ree-0-ee0xxeerrcciissee IIPPEE 11 HHRR 22 HHRR 44 HHRR 2244 HHRR 4488 HHRR7722 HHRR
Figure4.Mean(±standarddeviation)peakpoweroutput(watts)pre-eccentricexerc ise,immediate
Figure 4. Mean (± standard deviation) peak power output (watts) pre-eccentric exercise, immediate
Fppioogssutt r(e(IIP P4E.E )M), ,1e,1 a2,n, 2 4(,,± 2 4s4,t,a 42n84d ,aanr4dd8 d7a2en vhdioaut7i2rosn h()H opuRera)s kfo (pHr orRwes)eisrfto aornucrtpee sutirtsa t(iawnneacdtet smt)r epanirn ese-uedpccpmelenemtnriecns uetixpnepgrl cewimsiete,h ni mbtirnmagnecdwhieaidtthe-
pcbhoraasnitn c( IhaPemEd)i-,n c1oh, aa2ic,n i4d,a s2m (4Bi, nC4o8A aaAnc)id do s7r2 (p BhlaCocuAerbAso )( H(oPRrL)pC flBoar)c er(nebs o=is (2tPa0nL).cC *eB =t)r sa(iingnne=idfi2 cm0a)en.ntl *ysu =dpispfifgleenrmeifinetcn aftrninotgmly w pdiritfehf-e ebrxreeanrntccifhsreeo dm(p-
c<ph r0ea.-i0ne5x )ae fmrocriin sbeoo (taphc< iBd0Cs. A0(B5A)C fAaonrAdb) oPotLrh CpBBlCa.c AebAoa (nPdLCPLBC) (Bn. = 20). * = significantly different from pre-exercise (p
< 0.05) for both BCAA and PLCB.
3.4. MuscleSoreness
3.4. Muscle Soreness
3.4. MBuosthcleg Sroourepnsesdse monstratedsimilarpre-exerciseperceivedsorenessratings(BCAA=0±0;PLCB=
Both groups demonstrated similar pre-exercise perceived soreness ratings (BCAA = 0 ± 0; PLCB=
0±0cm). PerceivedsorenesswassignificantlyelevatedforbothBCAAandPLCBgroupsIPE,1,2,4,
Both groups demonstrated similar pre-exercise perceived soreness ratings (BCAA = 0 ± 0; PLCB=
0 ± 0 cm). Perceived soreness was significantly elevated for both BCAA and PLCB groups IPE, 1, 2, 4,
24,48and72hrpost-eccentricexercise(p<0.05),howevertheBCAAgroupreportedsignificantlyless
0 ± 0 cm). Perceived soreness was significantly elevated for both BCAA and PLCB groups IPE, 1, 2, 4,
24, 48 and 72 hr post-eccentric exercise (p < 0.05), however the BCAA group reported significantly
24, 48 and 72 hr post-eccentric exercise (p < 0.05), however the BCAA group reported significantly
Nutrients 2018, 10, x FOR PEER REVIEW 9 of 15
NNuuttrriieennttss 22001188,, 1100,, 1x3 F8O9R PEER REVIEW 99 ooff 1155
less soreness (p < 0.01) at 48 hr (BCAA: 4.59 ± 1.42; PLCB: 7.14 ± 1.65 cm) and 72 hr post-exercise
(lBesCsA sAor: e1n.3e8s s± (1p. 8<3 0c.m01;) P aLtC 4B8: h3.r9 0(B ±C 1A.5A2: c4m.5)9 ( F±i g1u.4r2e; 5P).L CB: 7.14 ± 1.65 cm) and 72 hr post-exercise
soreness(p<0.01)at48hr(BCAA:4.59±1.42;PLCB:7.14±1.65cm)and72hrpost-exercise(BCAA:
(BCAA: 1.38 ± 1.83 cm; PLCB: 3.90 ± 1.52 cm) (Figure 5).
1.38±1.83cm;PLCB:3.90±1.52cm)(Figure5).

Figure 5. Mean (± standard deviation) perceived soreness rating (cm; centimeters) pre-eccentric
Figure 5. Mean (± standard deviation) perceived soreness rating (cm; centimeters) pre-eccentric
eFxiegrucrisee ,5 .i mMmeaend ia(±te stpaonsdt ar(IdP Ed)e, v1ia, ti2o,n )4 , p2e4rc, e4iv8e da nsdo r7e2n ehsso urarst in(gH R(c)m f;o rc ernetsimisteatnecrse) tprarein-eecdc emnternic
exercise, immediate post (IPE), 1, 2, 4, 24, 48 and 72 hours (HR) for resistance trained men
seuxpeprcliesme,e nimtinmge wdiiathte b rpaonsct h(eIdP-Ec)h, ai1n, a2m, i4n,o 2a4c,i d4s8 ( BaCnAd A7)2 o rh poluarcse b(oH (RP)L CfoBr) (rne s=i s2t0a)n. c*e = tsriaginniefidc amntelyn
supplementingwithbranched-chainaminoacids(BCAA)orplacebo(PLCB)(n=20).*=significantly
dsuifpfeprleenmt efrnotmin gp rwei-tehx ebrrcainsec hfoedr -bcohtahi nB CamAiAn oa nacdi dPsL (CBBC A(pA <) 0 o.0r 5p)l; a^c e=b soig (nPiLfiCcaBn) t(lny =d 2if0fe).r *e n=t s firgonmif iPcaLnCtlBy
differentfrompre-exerciseforbothBCAAandPLCB(p<0.05);ˆ=significantlydifferentfromPLCB
gdrioffuepre (npt <f r0o.0m5 )p. re-exercise for both BCAA and PLCB (p < 0.05); ^ = significantly different from PLCB
group(p<0.05).
group (p < 0.05).
3.5. Blood Parameter: Creatine Kinase
3.5. BloodParameter: CreatineKinase
3.5. Blood Parameter: Creatine Kinase
Figure 6 displays the changes in plasma CK activity over the course of the experimental period.
Figure6displaysthechangesinplasmaCKactivityoverthecourseoftheexperimentalperiod.
ThereF wigeurree n6o d sisigpnlaifyisc atnhte dcihfafenrgeensc eins pbelatwsmeean C gKr oauctpivs iatyt porvee-re xtheerc cisoeu r(pse > o 0f. 0th5e; BeCxpAeAri m= e1n3t4a.l5 p±e 3ri4o.0d;.
Therewerenosignificantdifferencesbetweengroupsatpre-exercise(p>0.05;BCAA=134.5±34.0;
PTLhCerBe =w 1e1r7e. 3n o± s3i4g.8n iIfUic/aLn)t. dPilfafsemrean CceKs bcoetnwceenetnr agtrioounsp sw aetr ep rseig-enxiefirccaisnet l(yp e>l e0v.0a5te; dB CabAoAve = b 1a3s4e.l5in ±e 3(4p. 0<;
PLCB = 117.3 ± 34.8 IU/L). Plasma CK concentrations were significantly elevated above baseline
0P.0L0C1B) i=n 1b1o7t.h3 B± C3A4.A8 IaUn/dL )P. LPAla sgmroau CpKs a cto 4n, c2e4n, t4r8a taionnds 7 w2 ehrre p soigstn-iefxicearncitsley. eWlehvialete ndo a sbigovneif ibcaasnetl ignreo u(pp <-
(p<0.001)inbothBCAAandPLAgroupsat4,24,48and72hrpost-exercise. Whilenosignificant
b0y.0-0ti1m) ein e bffoetcht BwCaAs Ade atencdte PdL fAo rg prolauspms aa tC 4K, 2 (4p, =4 80 a.1n0d), 7p2l ahsrm pao sCt-Ke xleervceilsse .w Werhei lsei gnnoi fsiicgannitfliyca lnotw gerro ufopr-
group-by-timeeffectwasdetectedforplasmaCK(p=0.10),plasmaCKlevelsweresignificantlylower
tbhye- tBimCAe Aef fgercotu wpa ast d4e8t ehcrt pedo sfto-er xpelracsimsea ( pC =K 0 (.p0 2=; B0.C10A)A, p: l7a9s9m.2a ±C 1K9 7l.e6v; ePlsL CwBe:r e1 4s2ig2.n9i f±i c6a3n0t.l8y IlUow/Le).r for
fortheBCAAgroupat48hrpost-exercise(p=0.02;BCAA:799.2±197.6;PLCB:1422.9±630.8IU/L).
the BCAA group at 48 hr post-exercise (p = 0.02; BCAA: 799.2 ± 197.6; PLCB: 1422.9 ± 630.8 IU/L).

Figure6. Mean(±standarddeviation)plasmacreatinekinase(IU/L;internationaluni tsperliter)
Figure 6. Mean (± standard deviation) plasma creatine kinase (IU/L; international units per liter) pre-
pre-eccentricexercise, 4, 24, 48and72hours(HR)forresistancetrainedmensupplementingwith
eFcicgeunrter i6c. Mexeearcni s(e±, s4ta, n2d4a, rd48 d eavnida ti7o2n )h poluarssm (aH cRre)a tfionre rkeisniastsaen (cIUe /tLra; iinnetedr nmateionn saul pupnlietsm peenrt liintger )w pirteh-
branched-chain amino acids (BCAA) or placebo (PLCB) (n = 20). * = significantly different from
bercacnecnhtreidc -cehxaeirnci saem, i4n,o 2a4c,i d4s8 ( BaCndA A72) ohro pulrasc e(bHoR ()P LfoCrB )r e(sni s=t a2n0c)e. * t=ra siingendif imcaennt lys udpifpfleermenetn ftrionmg wprieth-
pre-exercise(p<0.001);ˆ=significantlydifferentfromPLCBgroup(p=0.02).
ebxrearnccishee d(p- c<h 0a.i0n0 1a)m; ^in =o saigcindisfi c(BanCtAlyA d)i fofre rpelnatc efrboom (P PLLCCBB) g(nr o=u 2p0 ()p. *= = 0 .s0ig2)n. ificantly different from pre-
4. Diesxceurscsisieo n(p < 0.001); ^ = significantly different from PLCB group (p = 0.02).
4. Discussion
TheaimofthepresentstudywastoexaminetheeffectofBCAAsupplementationonindices
4. Discussion
ofmTuhscel eaidma mofa tghee ipnreresesinstt asntucde-yt rwaianse tdo mexeanmcionnes tuhme einffgecat sotfr iBcCtpArAot seuinppdlieemtienntteantdioend otno ipnrdoivciedse oaf
mpruostecTlienh iedn aatamimkae gooeff ti1hn.e2 rpger/seikssgtea/nndtc asety-u.trdTaoyin dweadatse m,ttohe enisx aicsmotnhisneuefim trhisnet gse tfuafed csytt roeicxf taB mpCriAnoitAne igsnut hpdepieplte omitneetnnetntiaadtleioodfn a tooBn Cp inrAodAviciddeose soaef,
pnmroourtmsecilanel iizdnetadamkteao gobefo 1idn.2y rgme/skaigsss/tda,ntaocye.m -Ttirotai gdinaaettede, d tmahmiesn ai sgc etohnaens fudirmsetni nshgtau ndac yes terrxeicactmo vpienrroiyntegfio ntlh loed wipeoitn tiegnntatecinauldt oeefds aq tuBoaC tpAercAocv edindotesr eiac,
protein intake of 1.2 g/kg/day. To date, this is the first study examining the potential of a BCAA dose,
Nutrients2018,10,1389 10of15
exerciseinresistance-trainedmalesundergoingstrictdietarycontrol. Theabilityofoureccentricsquat
exerciseprotocoltoevokeskeletalmuscledamagewasindirectlyevaluatedbypost-exercisechanges
inpowerproduction,isometricforceloss,plasmaCKconcentrationsandparticipants’sorenessratings.
Itisevidentfromthesignificanttimeeffects[10,32,33]andmagnitudeofresponseforeachofthese
indicesthatmuscledamagewasinflicted[34],thusallowingustosufficientlystudyrecoveryupto
72hrpost-exercise. Toourknowledge,thiseccentricexerciseprotocolhasneverbeenusedinprevious
research;however,ourdatasupporttheefficacyofthisprotocoltoinducemuscledamageusinga
manneroftrainingthatmaybeimplementedintoaresistancetrainee’sprogram.
Proficient recovery procedures following strenuous, muscle-damaging exercise sessions are
importantforsupportingtraining-inducedadaptationandpromotingqualitysubsequentexercise
sessions. Aminoacidshavebeenshowntoincreaseproteinsynthesisinthepost-exerciseperiod[35,36]
and their consumption by athletes and recreationally trained individuals is a common practice to
promote recovery. Research suggests greater protein synthetic rates and amino acid availability
reducesdamagetomyofibrillarandcytoskeletalproteins,therebyhelpingtopreserveforceproduction
abilities[36,37].
Themuscleforcegeneratingcapabilitiesduringtherecoveryperiodfollowingeccentricexercise
havebeensuggestedtobeoneofthemostreliableindicesofmuscledamageduetotherelationship
betweenmuscleforceandmusclefunction[34]. Therefore,wechosetoexaminetheeffectofBCAA
supplementation on recovery of muscle force production during an MVIC of the dominant leg
quadricepsmusclesaswellastoevaluaterecoveryofmoreballisticmovements. Whilewefoundno
differencesinverticaljumpheightorloadedjumpsquatpeakpowerbetweengroups,MVICforce
recovery was significantly recovered at 24, 48 and 72 hr post-exercise time-points for the BCAA
group. ThesefindingsaresimilartothatofHowatsonandcolleagues[10]whoreportedasignificantly
lowerdecrementinMVICforceproductionandincreasedforceproductionrecoveryintrainedmales
supplementingwith20gperday(10gtwiceperdayofBCAA,anadditional20gbolusonehour
pre-exercise,andanother20grambolusimmediatelypost-exercise).However,theparticipants’vertical
jumpheightwasunaffected. Ontheotherhand,Foureetal.[16]reported7gofBCAAperdayhad
noeffectonrecoveryofquadricepsMVICinrecreationallytrainedmalesfollowingmuscledamage.
Likewise,inastudybyJackmanetal.[15],nodifferencesweredetectedinforceproducingcapabilities
inuntrainedmalessupplementingwith29.3gofBCAAperdayasmeasuredbyMVIC.Kirbyand
coworkers[38]examinedtheeffectof250mg/kgoftheBCAAleucineonrecoveryofforceproduction
andverticaljumpheight. Whilenodifferencesinjumpheightweredetected,leucineattenuatedmean
peakforcedecrementsacrossallpost-exercisetimepoints(upto96hr)inuntrainedmales. Similar
resultsfromtwocross-overinvestigationsexaminingBCAAsupplementationonrecoveryofmuscle
functioninuntrainedindividualsreportedfavorableoutcomesofmusclefunctionassessments[39,40].
However,thesefindingsmaybeinfluencedbytherepeatedboutphenomenaandshouldbeconsidered
alimitation[41,42]. WhileMVICtestingisapopular,validandreliablemeasureofmusclefunction
andrecovery[43],itisimportanttonotethattheisometricmovementassociatedwithMVICtesting
isdistinctlydifferentfromseveraltypesofathleticperformancemovements. Thoughourdataand
others’work[10,12]suggestenhancedrecoveryofforceproductioninindividualsconsumingBCAAs,
nostudiestodateprovideevidencethatBCAAsupplementationsupportsrecoveryofmoreballistic
andfunctionalmovements[10,17,38].
WhileourdatasuggestaminorimpactofBCAAsupplementationonmusclefunctionduring
recoveryfrommuscledamagingexercise,theBCAAgroupalsoreportedsignificantlylesssoreness
48 and 72 hr post-exercise. This is in agreement with previous work [15,44] and suggests the
relationshipbetweenmuscularfunctionandsorenessisnotnecessarilyinverselyrelated. Eventhough
no improvement in muscle function was detected, untrained men consuming a diet consisting of
1.5g/kg/dayofproteinandfourdosesof7.3gBCAAperdayreportedsignificantlylesssoreness
72hrposteccentricexercise[15]. SimilarfindingsbyHowatsonetal.[10]andShimomuraetal.[39]
werereported24and48hrpostresistance-basedmuscledamagingexerciseinindividualsconsuming