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Effects of Creatine Supplementation on Lower-Limb Muscle Endurance Following an Acute Bout of Aerobic Exercise in Young Men

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We aimed to determine whether creatine supplementation influences lower-limb muscle endurance following an acute bout of aerobic exercise (AE) in young healthy men. Using a randomized, double-blind, placebo-controlled crossover design, 11 men (26.5 ± 6.2 years, body mass index 26.6 ± 2.1 kg/m2),with 12 months of experience in strength training (three times/week) and AE (two times/week) were randomized to receive creatine (20 g/day plus 20 g/day maltodextrin) and placebo (40 g/day maltodextrin) for 7 days, separated by a washout period of 14 days, before performing an acute bout of AE (30 min on treadmill at 80% baseline maximum velocity) which was followed by four sets of bilateral leg extension endurance exercise using a 10-repetition maximum protocol (10 RM)). There was a significant decrease in the number of repetitions performed in the third (Placebo: −20% vs. Creatine: −22%) and fourth set (Placebo: −22% vs. Creatine: −28%) compared with the first set (p < 0.05), with no differences between creatine and placebo. Additionally, no differences were observed between creatine and placebo for the total number of repetitions performed across all four sets (Placebo: 33.9 ± 7.0 vs. Creatine: 34.0 ± 6.9 repetitions, p = 0.97), nor for total work volume (Placebo: 3030.5 ± 1068.2 vs. Creatine: 3039.8 ± 1087.7 kg, p = 0.98). Short-term creatine supplementation has no effect on lower-limb muscle endurance following an acute bout of aerobic exercise in trained young men.
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Sports2020,8,12;doi:10.3390/sports8020012www.mdpi.com/journal/sports
Article
EffectsofCreatineSupplementationonLowerLimb
MuscleEnduranceFollowinganAcuteBoutof
AerobicExerciseinYoungMen
ItamarP.Vieira
1
,AmandaG.dePaula
1
,PauloGentil
2
,ClaudePichard
3
,DarrenG.Candow
4
andGustavoD.Pimentel
1,
*
1
ClinicalandSportsNutritionResearchLaboratory(Labince),FacultyofNutrition,FederalUniversityof
Goias,74605080Goiânia,Brazil;itamarpef@gmail.com(I.P.V.);mnd.gms1@gmail.com(A.G.d.P.)
2
FacultyofPhysicalEducationandDance,FederalUniversityofGoias,74605080Goiânia,Brazil;
paulogentil@hotmail.com
3
ClinicalNutrition,GenevaUniversityHospital,1205Geneva,Switzerland;claude.pichard@unige.ch
4
FacultyofKinesiologyandHealthStudies,UniversityofRegina,Regina,SKS4SOA2,Canada;
darren.candow@uregina.ca
*Correspondence:gdpimentel@gmail.com;Tel.:+556232096270
Received:25November2019;Accepted:6January2020;Published:21January2020
Abstract:Weaimedtodeterminewhethercreatinesupplementationinfluenceslowerlimbmuscle
endurancefollowinganacuteboutofaerobicexercise(AE)inyounghealthymen.Usinga
randomized,doubleblind,placebocontrolledcrossoverdesign,11men(26.5±6.2years,bodymass
index26.6±2.1kg/m
2
),with12monthsofexperienceinstrengthtraining(threetimes/week)andAE
(twotimes/week)wererandomizedtoreceivecreatine(20g/dayplus20g/daymaltodextrin)and
placebo(40g/daymaltodextrin)for7days,separatedbyawashoutperiodof14days,before
performinganacuteboutofAE(30minontreadmillat80%baselinemaximumvelocity)whichwas
followedbyfoursetsofbilaterallegextensionenduranceexerciseusinga10repetitionmaximum
protocol(10RM)).Therewasasignificantdecreaseinthenumberofrepetitionsperformedinthe
third(Placebo:−20%vs.Creatine:−22%)andfourthset(Placebo:−22%vs.Creatine:−28%)compared
withthefirstset(p<0.05),withnodifferencesbetweencreatineandplacebo.Additionally,no
differenceswereobservedbetweencreatineandplaceboforthetotalnumberofrepetitions
performedacrossallfoursets(Placebo:33.9±7.0vs.Creatine:34.0±6.9repetitions,p=0.97),nor
fortotalworkvolume(Placebo:3030.5±1068.2vs.Creatine:3039.8±1087.7kg,p=0.98).Shortterm
creatinesupplementationhasnoeffectonlowerlimbmuscleendurancefollowinganacuteboutof
aerobicexerciseintrainedyoungmen.
Keywords:creatine;aerobicexercise;concurrentexercise;strengthloss;muscle
1.Introduction
Concurrentexercise(CE)involvesthecombinationofaerobicexercise(AE)andresistance
traininginthesametrainingsession[1].CEiscommonpracticeamongexercisingindividualsand
athletesandincreasesphysicalperformanceandbodycomposition[2–6].However,previousstudies
haveshownthatperformingAEbeforeresistancetrainingresultsinacutedecreasesinmuscle
performance[2,4,7–10],possiblyduetoanincreaseinperipheralfatigue,AMPactivatedprotein
kinase(AMPK)andPeroxisomeproliferatoractivatedreceptorgammacoactivator1alpha(PGC1α)
signalinganddecreaseinsatellitecellactivity[1].
Sports2020,8,122of9
Supplementationwithcreatine,anorganicacidderivedfromreactionsinvolvingarginine,
methionine,andglycineinthekidneyandliver[1],hasbeenshowntoincreasemuscleperformance,
possiblybyinfluencinghighenergyphosphatemetabolism,satellitecellactivity,muscleprotein
kinetics,andinflammation[11,12].Theoretically,creatinesupplementationmaybeaneffective
nutritionalinterventionfollowingAEtomaintainmuscleperformance.Forexample,Painellietal.
[4]showedthatcreatinesupplementation(20g/dayfor7days+5g/daythereafter)maintainedlower
bodymuscleendurance(numberofrepetitionsperformed)followingacuteboutsofintermittentand
continuousAEinstrengthtrainedmalescomparedwithadecreaseinmaleswhoreceivedplacebo.
However,thisstudywaslimitedbytheparallelgroupdesign.
Thepurposeofthisstudywastodeterminewhethercreatinesupplementationmaintainsmuscle
performancefollowinganacuteboutofAEintrainedyoungmalesusingarandomized,crossover
design.Crossoverdesignstypicallyreducetheinfluenceofconfoundingvariablesonthedependent
outcomemeasuresandareconsideredmorestatisticallypowerful(lessvariance)comparedwith
parallelgroupdesigns.BasedonthemechanisticactionsofcreatineandthefindingsofPainellietal.
[4],itwashypothesizedthatcreatinesupplementationwouldmaintainlowerlimbmuscleendurance
followinganacuteboutofAEcomparedwithplacebointrainedyoungmales.
2.Methods
2.1.Participants
Seventeenmenwith12monthsofstrengthtraining(threetimesperweek)andAE(twotimes
perweek)experiencevolunteered.Participantswereexcludediftheywerevegetarian,hadconsumed
proteinorcreatinesupplementssixmonthspriortothestartofthestudy,iftheyhadahistoryof
hormonaltherapyinterventionsoranabolicsteroiduse,oriftheyhadpreexistingkidneyorliver
abnormalities.Participantswereinstructednottochangetheirdietorphysicalactivitypatterns
duringthestudy.Participantswereinformedoftherisksanddiscomfortsassociatedwiththestudy
beforeprovidingwrittenconsent.ExperimentaldesignwasapprovedbytheResearchEthics
Committee(no.2.507.216),andafterestablishingtheinclusionandexclusioncriteria,theparticipants
signedtheinformconsentform.
2.2.StudyOverview
Thestudywasadoubleblind,placebocontrolledcrossovertrialwhereparticipantswere
randomizedusingacomputergeneratedschedule(https://www.randomizer.org/)toconsume
creatineandplacebofor7days,separatedbya14daywashoutperiod.Aftereach7days
supplementationphase,participantsperformedanacuteboutofAEexperimentaltestconsistingof
a30minrunonatreadmill(Technogym®,ExciteRun1000,Cesena,Italy)at80%maximumvelocity
(MV)obtainedinthetest.Immediatelyfollowingthetreadmillexercise,participantsperformedfour
setsofbilaterallegextensionexercise(Technogym®,LegExtensionMed,SãoPaulo,Brazil)withthe
loadobtainedonthe10repetitionmaximum(10RM)test.Allsetswereperformedtomomentary
musclefailureaspreviouslydefined[13].Restbetweensetswas2min.Bloodglucoseandlactate
concentrationsweredeterminedbeforeandaftertheacuteboutofAEtests.Duringthe14days
washoutperiod,nosupplementwasconsumed(Figure1).PriortotheacuteboutofAE,participants
wereinstructedtoabstainfromalcohol,caffeine,othersupplements,andstrenuousexercisefor48h.
Participantsarrivedfortesting1haftertheirlastmealandpretestfeedingwasstandardized(yogurt
withbanana).Adlibitumwaterconsumptionwasallowedduringthetestsandfoodintakewas
measuredusingthree24hfoodrecalls.Priortorandomizationandsupplementation,participants
performedafamiliarizationtrialwiththeexerciseequipmenttoreducetheamountoflearningwhich
mayhavecontributedtoourfindings.
Sports2020,8,123of9
Figure1.Experimentaldesign.Afteranamnesis,anthropometricevaluation,strengthtests,and
exercisefamiliarization,elevenparticipantsonahighproteindietandplaceboorcreatine
supplementationforoneweekweresubmittedtoacuteconcurrentexercisesession.Afterawashout
periodoffourteendays,thesameprotocolwasrepeated.
2.3.Supplementation
Participantsingested20gofcreatinemonohydrate(20g;MaxTitanium®,Supley,Matão,Brazil;
99.9%purity)and20gmaltodextrinor40gofmaltodextrin(placebo,MaxTitanium®,Supley,Matão,
Brazil)for7days.Afterthe14dayswashoutperiod,participantscrossedoverandconsumedthe
oppositesupplementfor7days.Thetotaldailyamountofsupplementwasdividedintofourequal
portionsandconsumedwithfoodthroughouttheday.Creatineandplacebowereidenticalintaste,
color,texture,andappearance.Supplementpackageswereunmarkedsoneithertheparticipantnor
theresearcherknewthecontent.
2.4.AnthropometricMeasures
Bodymasswasmeasuredusingadigitalpersonalscale(HN289LA®OmronHealthcareCo.,
Muko,Kyoto,Japan)andheightusingaportablestadiometer(Sanny®,SãoPaulo,Brazil),andbody
massindex(BMI)wasthencalculated.Upper‐ andlowerlimbandwaistcircumferencewas
measuredtwiceusingatapemeasure.Skinfoldthicknesses(subcutaneousadiposetissue)were
measuredusingacaliper(Lange®SkinfolderCaliper,BetaTechnology,SantaCruz,USA)andbody
fatwascalculatedaccordingtotheJacksonandPollockprotocol[14].Anthropometricassessments
wereperformedbythesametrainedresearcher.
2.5.DietaryIntakeAnalyses
Dietaryintakewasassessedbyhavingparticipantsfilloutthree24hfooddiariesonseparate
days(twoweekdaysandoneweekendday)toevaluatehabitualfoodconsumption[15].Thedietary
intakeanalysisconsistedoftotalcalories,carbohydrate,lipids,proteins,leucine,valine,and
isoleucine.FoodintakecalculuswasperformedusingtheDietPro®software(version6.0,Viçosa,
Brazil)usingtheFoodDatabaseTableoftheUnitedStatesDepartmentofAgriculture[16].
2.6.MaximumGradedTest
Amaximalgradedexercisetestwasperformedonatreadmill(Technogym®,ExciteRun1000,
Cesena,Italy),withslopesetat1%.Afterawarmupthatconsistedofwalkingat6.0km/hfor3min,
thetreadmillwasadjustedwiththespeedof8.0km/h,followedbyanincreaseof1.0km/hineach
subsequentminuteuntiltheparticipantsreachedexhaustion.Thevelocityatthelastcompletestage
beforeexhaustionwasrecordastheMV.Participantswerestronglyencouragedverballytoexert
maximumeffort[17].

Sports2020,8,124of9
2.7.MaximumRepetitionStrength(10RM)andStrengthEnduranceTest
The10repetitionmaximum(10RM)testwasperformedusingthelegextensionmachine
(Technogym®,LegExtensionMed,SãoPaulo,Brazil).Theproceduresfollowedtherecommendations
previouslydescribed[10,18].Theparticipantsperformedthewarmupwithtenrepetitions
performedataselfselectedcomfortableload.Afterarestof5min,theestimated10RMloadwas
adjustedbasedonthetraininghistoryofeachparticipant.Ifthevolunteerwasnotabletoperform
tenrepetitionsorperformedmorethantenrepetitions,theloadwasadjustedforthenextattempt.
Onlythreeattemptswereallowed,withrestof5minbetweenthem.The10RMloadswereobtained
forallparticipantsintwotothreeattempts.Participantsperformedthetestswiththeirbacksin
contactwiththesupportandwerenotallowedtousetrunkmovementsorraisetheirhipsfromthe
chair.Thetestswerestoppedwhentheparticipantswereunabletodothemovementproperly(total
rangeofmotionwithoutchangesinthetechnique)fortwoconsecutiverepetitions.The
familiarizationofstrengthendurancetestinvolvedoftheconclusionoffoursetstofailureat80%of
theloadaspertheprotocolpublishedpreviously[4].Thetestswereperformedbytrained
professionalsandverbalmotivationwasusedinallsets.
2.8.BiochemicalAnalysis
Bloodlactatewasmeasuredusingaportablelactometer(Accutrend®Plus;RocheAccutrend
Plus,NewYork,NY,USA).Bloodglucosewasmeasuredbydigitalglucosemeter(Accuchek®
Active;Roche,SãoPaulo,Brazil).Allbloodsamplesweretakenfromthefingerbyatrained
professional.
2.9.StatisticalAnalyses
ThenormalityofthedatawastestedusingtheKolmogorov–Smirnovtest.General
characteristics,dietaryfoodintake,legextensionrepetitions,andbloodlactateconcentrationsare
presentedasmean±standarddeviationandglucoselevelsarepresentedasmedian(minimumand
maximum).StrengthdatawereanalyzedusingthetwowayANOVAfollowedbyTukeytest.The
unpairedttestwasusedtocomparethetotalworkvolumeandbloodlactateconcentrationsbetween
groups.TheMann–Whitneytestwasusedtocomparethedeltabloodglucoseconcentrations.The
Fisherexacttestwasperformedtoassesstherateofparticipantswhocorrectlyguessedtheir
allocationinthegroup.AllstatisticalanalysesweredoneusingtheMedCalc®Seoul,Korea,software,
andp<0.05wasdefinedassignificantdifference.
3.Results
Ofthe17participantswhoinitiallyvolunteered,sixwereexcludedfornotadheringtotheproper
supplementationprotocol.Therefore,resultsfrom11participantswereusedintheanalyses.(Table
1).Priortostartingthestudy,allparticipantsfrombothgroupsingestedalowcarb(3.0±1.0
g/kg/day)andhighproteindiet(1.5±0.3g/kg/day),withnodifferenceindietaryintakebetween
interventionperiods(Table2).Nosideeffectswerereportedfromthesupplementationorexercise
intervention.Verbalconfirmationofsupplementationcompliancewas100%.
Table1.Participants’characteristics.
CharacteristicsMean±SD
Age(years)26.5±6.2
Bodyweight(kg)77.6±7.2
Height(m)1.7±0.0
Bodymassindex(kg/m2)26.6±2.1
Bodyfat(%)14.4±6.6
Workvolumelegextension(kg)88.1±18.6
Totalworkvolume(kg)3030.5±1068.2
Efforttimerunfor5km(min)25.5±2.6
Sports2020,8,125of9
Table2.Dietaryfoodintake.
NutrientsMean±SD
Totalcalories(kcal)2196.6±702.9
Carbohydrate(%)43.6±8.2
Carbohydrate(g/kg)3.0±1.0
Protein(%)26.4±4.3
Protein(g/kg)1.5±0.3
BCAA(g)19.0±6.1
Leucine(g)8.3±2.9
Valine(g)5.8±1.8
Isoleucine(g)4.8±1.5
Lipids(%)29.9±9.5
BCAA:Branchedchainaminoacids.
AfterAE,therewasasignificantreduction(p<0.05)inlegextensionmuscleendurance(number
ofrepetitionsperformed)inthethird(Placebo:−20%vs.Creatine:−22%)andfourthset(Placebo:
22%vs.Creatine:−28%)comparedwiththefirstset.However,therewerenodifferencesbetween
creatineandplacebo(Figure2A).Acrossallfoursets,nodifferenceswereobservedinthetotal
numberofrepetitionsperformed(Placebo:33.9±7.0vs.Creatine:34.0±6.9repetitions,p=0.97)
(Figure2B).Additionally,nodifferenceintotalworkvolumewasfoundbetweencreatineand
placeboinkg(Placebo:3030.5±1068.2vs.Creatine:3039.8±1087.7kg,p=0.98)(Figure3)andjoules
(Placebo:3030.4±1068.2vs.Creatine:3035.5±1092.8J/m,p=0.99).
Figure2.Strengthenduranceinlegextension(repetitions)amongthesets(A)andlegextension(sum
ofrepetitions)(B).
Sports2020,8,126of9
Figure3.Meanvaluefortotalwork(kg)usingthelegextensionmachineeitheronplaceboorcreatine
supplementation.
Therewerenosignificantdifferencesbetweencreatineandplaceboforchangesindeltablood
glucose(Placebo:5.0(73.0–67.0)vs.Creatine:1.0(53.0–49.0)mg/dL,p=0.73)andbloodlactate
(Placebo:5.1±2.9vs.Creatine:7.9±4.9nmol/L,p=0.11)concentrations(seeSupplementaryFigure
S1).
Regardingsupplementblindingefficacy,6/11participantscorrectlyguessedwhentheywere
consumingplaceboand5/11correctlyguessedwhentheywereconsumingcreatine,whichwasnot
statisticallydifferent(p=1.00).
4.Discussion
TherearetwohypothesesforthereductioninmuscleendurancefollowingAE,(i)acute;
peripheralfatiguetriggeredbymuscledamageandglycogendepletionduringAEtrainingreduces
theabilityofskeletalmuscletoproducetensionduringresistancetraining[2,3],and(ii)chronic;
skeletalmuscleattemptstoadapttobothformsoftraining,however,morphofunctionaladaptations,
suchasfibertypeandsizeafterenduranceexerciseandweighttrainingarepartiallyopposed
resultinginaninterferenceeffect.
Thecurrentstudyaimedtoassesstheinfluenceofcreatinesupplementationonmuscle
endurancefollowinganacuteboutofAEintrainedyoungmales.Resultsshowedthatcreatinehad
noeffectonmuscleenduranceortotalworkperformedwhichisincontrasttothefindingsofPainelli
etal.[4],whoshowedthatcreatinesupplementation(20g/dayfor7days+5g/daythereafter)
maintainedlowerbodymuscleendurance(numberofrepetitionsperformed)followingacutebouts
ofintermittentandcontinuousAEinstrengthtrainedmales(n=15)comparedwithadecreasein
males(n=16)whoreceivedplacebo.Theauthorssuggestthattheincreasedavailabilityofphosphoryl
creatineanditspotentialbufferingcapacity(reductionofH+ions)wouldberesponsiblefor
maintainingmuscleenduranceinthelegs.Furthermore,infemaleswhoperformedalegpress1RM
priortoandimmediatelyfollowinganacuteboutofenduranceexercise,therewasapositiveeffect
fromcreatinesupplementationontheperformanceoffoursetsoflegpressat80%of1RM[8].While
itisdifficulttocompareresultsacrossstudies,methodologicaldifferencesmaybeinvolved.Inthe
Painellietal.[4]study,legpressandchestpressmuscleendurance(bothmultijointexercises)was
assessedwhereasweonlyassessedlegextensionendurance(singlejointexercise).Furthermore,
femaleswereassessedinthestudybyAokiwhereasweassessedonlymales.Previousstudieshave
showndifferencesinmusclefatigability[6,8,19]andresponsivenesstocreatinesupplementation
betweensexes[20,21].
Additionally,nodifferenceinbloodlactateconcentrationswasreported.Thesedataaresimilar
tothosefromapreviousstudy[22].
Sports2020,8,127of9
Ourdatashownopositiveeffectofcreatinesupplementationonmusclestrengthusinga
crossoverdesignandwithdietarycontrolduringthestudy.Consideringthattheparticipantswere
onahighproteindiet,thecreatinesupplementationmightbenotnecessary.Thismightbeexplained
becauseproteiningestioncanhelpinmusclerecovery[23]andmightinfluencerecoveryfromaerobic
activities.However,creatinesupplementationitseemsdidnotbringadditionalbenefitsinmenwho
intakeahighproteinandlowcarbdiet.
Arecentstudy[5]investigatedachronicproteinsupplementationeffect(6months)onmuscle
strengthinsedentarywomenandmenonCE.Menwhoingestedproteinsupplementation2.2
g/kg/day,showedhigherincreasesinstrengthinthebenchpresswhencomparedwiththegroupthat
ingested1.1g/kg/dayofprotein.Itisinterestingtonotethatmenwhoreceivedahighprotein(2.2
g/kg/day)groupingestedlowercarbohydrate(notlowcarbdiet)thanthenormalprotein(1.1
g/kg/day)group.Ontheotherhand,inwelltrainedmalecyclistswhoperformedanacuteexercise
session(highintensitycyclingand100dropjumps),20ghydrolysateproteinsupplementation
associatedwithahabitualhighproteindiet(1.2g/kg/day)andmoderateincarbohydrate(6g/kg/day)
didnotalleviateexerciseinducedmuscledamage[7].
Althoughtrainingenhancestheeffectivenessofsupplementationproteinduringresistance
exercise[24],theeffectsofhabitualconsumptionofahighproteindietonmusclestrengthduring
concurrenttrainingarelimited[5].Itwouldbeinterestingiffuturestudiesevaluatetheeffectsof
creatinesupplementationunderhigh‐andlowhabitualproteinandcarbohydrateintakes.
Althoughwedidnotmeasurethetimingofproteinintake,nosignificanteffectonmuscle
strengthisfoundduringtheresistancetraining[25].Thus,furtherstudiesarewarrantedtoexamine
theeffectsofahighproteindietonmusclestrengthduringaCEbout.
4.1.StudyLimitations
Therewereseverallimitationstothisstudy.First,weuseda14dayswashoutperiodbetween
creatineandplaceboingestionwhichmaynothavebeenlongenoughtoabolishtheresidual(carry
over)effectsofcreatine.Forexample,Vandenbergheetal.[26]showedthatcreatinesupplementation
(20g/dayfor4days)increasedintramuscularPCrconcentrations,whichweremaintainedwitha
maintenancedosageofcreatine(5g/day)for10weeks.Uponcreatinecessation,intramuscularPCr
concentrationsremainedelevatedfor28days.Second,nomeasureofintramuscularcreatine(PCr,
freeCr)wasassessedpriortoeachtestingphase.Initialintramuscularcreatinelevelstypically
determinetheresponsivenesstocreatinesupplementation[27].Third,participantsmayhavealready
beenconsuminghighamountsofdietarycreatinefromproteincontainingfoodproducts(i.e.,
seafood,meat,poultry)[28,29],whichattenuatedtheergogenicresponsetocreatine
supplementation.Foodrecordspriortothestartofsupplementationshowedthatparticipantswere
consumingapproximately1.5±0.3g/dayofprotein.Unfortunately,thefooddiariesdidnot
determinetheamountofdietarycreatineconsumed.Fourth,themajorityofintramuscularcreatine
isfoundintypeIImusclefibers.Youngindividualswiththehighestconcentrationandmusclecross
sectionalareaoftypeIIfibersrespondmorefavorablytocreatinesupplementation[30].
Unfortunately,nomeasureofmusclefibermorphologywasmadeinthisstudy.Finally,theabsence
ofpositiveeffectfoundcouldbeduetothefactofasmallsamplesize.Thus,astudywithalarge
samplesizeandparticipantswithdifferenttrainingstagesshouldbeexploredinthefuture.
5.Conclusions
Insummary,shorttermcreatinesupplementationhasnoeffectonlowerlimbmuscleendurance
followinganacuteboutofAEintrainedyoungmales.Ourresultsshownewinformationregarding
musclestrengthrecoveryafteranacuteboutofAEandraiseahypothesisthattheincreasein
carbohydrateintakecombinedwiththehighproteindietshouldbeinvestigated.
Sports2020,8,128of9
SupplementaryMaterials:Thefollowingareavailableonlineatwww.mdpi.com/xxx/s1,FigureS1:Deltablood
glucose(A)andlactate(B)concentrationsforparticipantseitheronplacebooroncreatinesupplementation.No
significantdifferencesobservedbetweengroups.
AuthorContributions:Conceptualization,I.P.V.,A.G.d.P.,P.G.,C.P.,D.G.C.andG.D.P.;DataCuration,I.P.V.,
A.G.d.P.,P.G.,G.D.P.;FormalAnalysis,I.P.V.,A.G.d.P.andG.D.P.;Investigation,I.P.V.,A.G.d.P.,P.G.and
G.D.P.;Supervision,P.G.,andG.D.P.;Writing—OriginalDraft,I.P.V.,A.G.d.P.,P.G.,C.P.andD.G.C.;Writing—
Review&Editing,P.G.,D.G.C.,andG.D.P.Allauthorshavereadandagreedtothepublishedversionofthe
manuscript.
Funding:Thisresearchreceivednoexternalfunding.
ConflictsofInterest:Nopotentialconflictofinteresttothisarticlehasbeenreported.
References
1. Coffey,V.G.;Hawley,J.A.Concurrentexercisetraining:Dooppositesdistract?J.Physiol.2017,595,2883–
2896,doi:10.1113/JP272270.
2. Leveritt,M.;Abernethy,P.J.;Barry,B.K.;Logan,P.A.ConcurrentStrengthandEnduranceTraining.Sport
Med.1999,28,413–427,doi:10.2165/0000725619992806000004.
3. Docherty,D.;Sporer,B.AProposedModelforExaminingtheInterferencePhenomenonbetween
ConcurrentAerobicandStrengthTraining.SportMed.2000,30,385–394,doi:10.2165/00007256200030060
00001.
4. deSallesPainelli,V.;Alves,V.T.;Ugrinowitsch,C.;Benatti,F.B.;Artioli,G.G.;Lancha,A.H.;Gualano,B.;
Roschel,H.Creatinesupplementationpreventsacutestrengthlossinducedbyconcurrentexercise.Eur.J.
Appl.Physiol.2014,114,1749–1755,doi:10.1007/s0042101429030.
5. Ormsbee,M.J.;Willingham,B.D.;Marchant,T.;Binkley,T.L.;Specker,B.L.;Vukovich,M.D.Protein
SupplementationDuringa6MonthConcurrentTrainingProgram:EffectonBodyCompositionand
MuscularStrengthinSedentaryIndividuals.Int.J.SportNutr.Exerc.Metab.2018,28,619–28,
doi:10.1123/ijsnem.20180036.
6. Gentil,P.;deLira,C.A.B.;Filho,S.G.C.;LaScalaTeixeira,C.V.;Steele,J.;Fisher,J.Highintensityinterval
trainingdoesnotimpairstrengthgainsinresponsetoresistancetraininginpremenopausalwomen.Eur.J.
Appl.Physiol.2017,117,1257–1265,doi:10.1007/s0042101736140.
7. Eddens,L.;Browne,S.;Stevenson,E.J.;Sanderson,B.;vanSomeren,K.;Howatson,G.Theefficacyof
proteinsupplementationduringrecoveryfrommuscledamagingconcurrentexercise.Appl.Physiol.Nutr.
Metab.2017,42,716–724,doi:10.1139/apnm20160626.
8. Gomes,R.V.;Aoki,M.S.Suplementaçãodecreatinaanulaoefeitoadversodoexercíciodeendurancesobre
osubseqüentedesempenhodeforça.Rev.Bras.Med.Esporte2005,11,131–134,doi:10.1590/S1517
86922005000200007.
9. deSouza,E.O.;Tricoli,V.;Franchini,E.;Paulo,A.C.;Regazzini,M.;Ugrinowitsch,C.Acuteeffectoftwo
aerobicexercisemodesonmaximumstrengthandstrengthendurance.J.StrengthCond.Res.2007,21,1286–
1290,doi:10.1519/R20686.1.
10. Kraemer,W.J.StrengthTesting:DevelopmentandEvaluationofMethodology.InPhysiologicalAssessment
ofHumanFitness;HumanKinetics:Champaign,IL,USA1995,pp.115–138.
11. Candow,D.G.;Forbes,S.C.;Chilibeck,P.D.;Cornish,S.M.;Antonio,J.;Kreider,R.B.Effectivenessof
CreatineSupplementationonAgingMuscleandBone:FocusonFallsPreventionandInflammation.J.Clin.
Med.2019,8,488,doi:10.3390/jcm8040488.
12. Kreider,R.B.;Kalman,D.S.;Antonio,J.;Ziegenfuss,T.N.;Wildman,R.;Collins,R.InternationalSocietyof
SportsNutritionpositionstand:Safetyandefficacyofcreatinesupplementationinexercise,sport,and
medicine.J.Int.Soc.SportsNutr.2017,14,18,doi:10.1186/s129700170173z.
13. Steele,J.;Fisher,J.;Giessing,J.;Gentil,P.Clarityinreportingterminologyanddefinitionsofsetendpoints
inresistancetraining.MuscleNerve2017,56,368–374,doi:10.1002/mus.25557.
14. Jackson,A.S.;Pollock,M.L.Generalizedequationsforpredictingbodydensityofmen.Br.J.Nutr.1978,40,
497–504.
15. Fisberg,R.M.InquéritosAlimentares:MétodosEBasesCientíficas;Manole:SãoPaulo,Brazil,2005.
16. USDAFoodCompositionDatabases.Availableonline:https://ndb.nal.usda.gov/ndb/(acessedon15
Sports2020,8,129of9
August2018).
17. Noakes,T.D.;Myburgh,K.H.;Schall,R.PeaktreadmillrunningvelocityduringtheVO
2
maxtestpredicts
runningperformance.J.SportsSci.1990,8,35–45,doi:10.1080/02640419008732129.
18. Kraemer,W.J.;Patton,J.F.;Gordon,S.E.;Harman,E.A.;Deschenes,M.R.;Reynolds,K.Compatibilityof
highintensitystrengthandendurancetrainingonhormonalandskeletalmuscleadaptations.J.Appl.
Physiol.1995,78,976–989,doi:10.1152/jappl.1995.78.3.976.
19. Hill,E.C.;Housh,T.J.;Smith,C.M.;Schmidt,R.J.;Johnson,G.O.Gender‐andMuscleSpecificResponses
DuringFatiguingExercise.J.StrengthCond.Res.2018,32,1471–1478,doi:10.1519/JSC.0000000000001996.
20. Johannsmeyer,S.;Candow,D.G.;Brahms,C.M.;Michel,D.;Zello,G.A.Effectofcreatinesupplementation
anddropsetresistancetraininginuntrainedagingadults.Exp.Gerontol.2016,83,112–119,
doi:10.1016/J.EXGER.2016.08.005.
21. Parise,G.;Mihic,S.;MacLennan,D.;Yarasheski,K.E.;Tarnopolsky,M.A.Effectsofacutecreatine
monohydratesupplementationonleucinekineticsandmixedmuscleproteinsynthesis.J.Appl.Physiol.
2001,91,1041–1047,doi:10.1152/jappl.2001.91.3.1041.
22. Greenhaff,P.L.;Casey,A.;Short,A.H.;Harris,R.;Soderlund,K.;Hultman,E.Influenceoforalcreatine
supplementationofmuscletorqueduringrepeatedboutsofmaximalvoluntaryexerciseinman.Clin.Sci.
1993,84,565–571,doi:10.1042/cs0840565.
23. Pasiakos,S.M.;Lieberman,H.R.;McLellan,T.M.Effectsofproteinsupplementsonmuscledamage,
sorenessandrecoveryofmusclefunctionandphysicalperformance:Asystematicreview.SportsMed.2014,
44,655–670,doi:10.1007/s4027901301377.
24. Morton,R.W.;Murphy,K.T.;McKellar,S.R.;Schoenfeld,B.J.;Henselmans,M.;Helms,E.Asystematic
review,metaanalysisandmetaregressionoftheeffectofproteinsupplementationonresistancetraining
inducedgainsinmusclemassandstrengthinhealthyadults.Br.J.SportsMed.2018,52,376–384,
doi:10.1136/bjsports2017097608.
25. Schoenfeld,B.J.;Aragon,A.A.;Krieger,J.W.Theeffectofproteintimingonmusclestrengthand
hypertrophy:Ametaanalysis.J.Int.Soc.SportsNutr.2013,10,53,doi:10.1186/155027831053.
26. Vandenberghe,K.;Goris,M.;VanHecke,P.;VanLeemputte,M.;Vangerven,L.;Hespel,P.Longterm
creatineintakeisbeneficialtomuscleperformanceduringresistancetraining.J.Appl.Physiol.1997,83,
2055–2063,doi:10.1152/jappl.1997.83.6.2055.
27. Lemon,P.W.R.Dietarycreatinesupplementationandexerciseperformance:Whyinconsistentresults?Can.
J.Appl.Physiol.2002,27,663–681.
28. Wyss,M.;KaddurahDaouk,R.Creatineandcreatininemetabolism.Physiol.Rev.2000,80,1107–1213,
doi:10.1152/physrev.2000.80.3.1107.
29. Jung,S.;Bae,Y.S.;Kim,H.J.;Jayasena,D.D.;Lee,J.H.Carnosine,anserine,creatine,andinosine5′
monophosphatecontentsinbreastandthighmeatsfrom5linesofKoreannativechicken.PoultSci.2013,
12,3275–3282,doi:10.3382/ps.201303441.
30. Syrotuik,D.G.;Bell,G.J.AcuteCreatineMonohydrateSupplementation:ADescriptivePhysiological
ProfileofRespondersvs.Nonresponders.J.StrengthCond.Res.2004,18,610–617,doi:10.1519/00124278
20040800000039.
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... There does not appear to be any significant improvement in aerobic performance with supplemental creatine use (22). In aerobic exercise the body relies primarily on oxidative phosphorylation for energy production, which is a metabolic pathway that does not directly utilize creatine (19,20). ...
... In aerobic exercise the body relies primarily on oxidative phosphorylation for energy production, which is a metabolic pathway that does not directly utilize creatine (19,20). Although it has been suggested that creatine supplementation may alter substrate utilization during aerobic activity leading to improvement in endurance performance, the evidence for this is lacking (22). The ergonomic benefits of creatine supplementation appear to diminish with increasing duration of activity (20). ...
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Creatine is a popular and widely used ergogenic dietary supplement among athletes, for which studies have consistently shown increased lean muscle mass and exercise capacity when used with short-duration, high-intensity exercise. In addition to strength gains, research has shown that creatine supplementation may provide additional benefits including enhanced postexercise recovery, injury prevention, rehabilitation, as well as a number of potential neurologic benefits that may be relevant to sports. Studies show that short- and long-term supplementation is safe and well tolerated in healthy individuals and in a number of patient populations.
... This test was performed according to the protocol of Vieira et al. (2020), where if the participant was not able to perform ten repetitions, the load was adjusted for the next attempt. Only three attempts were allowed, with a 3-min rest between them. ...
... Al respecto, en ejercicios de alta intensidad de menos de 10 segundos la fuente predominante de ATP es la producida a partir de la fosfocreatina, puesto que, la energía producida a partir de la glucólisis anaeróbica requiere de actividades de esfuerzo máximo de 10 a 30 segundos (Kreider & Stout, 2021). Gracias a las propiedades de la creatina se la ha utilizado para mejorar el rendimiento deportivo anaeróbico en deportistas (Directo et al., 2019), el entrenamiento en resistencia (Burke et al., 2008), rendimiento aeróbico (Vieira et al., 2020), composición corporal (Gualano et al., 2016), rehabilitación y recuperación (Deminice et al., 2013), lesiones cerebrales traumáticas (Vagnozzi et al., 2013) y procesamiento cognitivo . ...
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La creatina es un compuesto químico natural presente en pequeñas cantidades en el cuerpo y determinados alimentos y suplementos, cuya principal función es suministrar energía inmediata a los tejidos que requieren de mayor demanda energética como son los músculos y el cerebro que se encarga del procesamiento cognitivo y desarrollo de funciones como la memoria, atención, gnosias, praxias y funcionamiento ejecutivo. Determinar la efectividad del consumo de creatina sobre el funcionamiento cognitivo. Se ha realizado una revisión bibliográfica que incluye 10 artículos científicos publicados en Scopus, Web of Science, Pubmed y Taylor and Francis. La suplementación con creatina ayuda en el rendimiento de algunas de las tareas cognitivas evaluadas en cada estudio; de las siete investigaciones que analizan cambios en la puntuación de memoria, 2 refieren cambios estadísticamente significativos. Sobre los resultados de tiempos de reacción, vigilancia y atención, 2 de los 6 estudios refieren cambios a favor del consumo de creatina. En relación con el funcionamiento ejecutivo, sólo un estudio de los 5 refieren beneficios de la suplementación. En cuanto a la cognición global, 1 de los 2 estudios reporta cambios de puntuación a favor del grupo de intervención. La suplementación con creatina no reporta efectos positivos en todas las funciones cognitivas estudiadas, se trata de un compuesto que no reporta efectos secundarios nocivos, y que hoy en día es seguro y fácil de consumir.
... Izquierdo and associate [37] also reported positive effects on CMJ after an acute CrM supplementation protocol (20 g·day −1 x 5 days) in U16 national D-1 handball players. However, a recent study by Viera and coworkers [38] concluded that short-term CrM supplementation (20 g·day −1 plus 20 g·day −1 maltodextrin x 7 days) had no significant effects on lower-limb muscle endurance following an acute bout of 30-min exercise at 80% maximum velocity in trained young men. Rosene et al. [39] also reported that CrM supplementation did not attenuate exercise-induced muscle damage with short-term supplementation, but the ergogenic effect appeared after 30 days of supplementation. ...
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ÖZ: Bu çalışmanın amacı glutamin ve kreatin kombine tüketiminin bisikletçilerin performansına akut etkisinin incelenmesidir. Bu çalışmaya lisanslı, aktif ve antrenmanlı 8 erkek bisikletçi (yaş: 25,85 ± 9,75 yıl; boy uzunluğu: 174,71 ± 5,18 cm; vücut ağırlığı: 69,81 ± 7,16 kg; beden kütle indeksi (BKİ): 22,95 ± 2,97 kg/m2 ; sporcu yaşı: 5,28 ± 2,28) gönüllü olarak katıldı. Randomize, tek kör ve çapraz döngü çalışmada, bisikletçiler rastgele 2 gruba ayrıldı ve 48 saat ara ile glutamin&kreatin (SUP) veya plasebo (PLA) alarak fonksiyonel eşik güç (FTP) testini uyguladı. Testlerin ardından Borg Skalası, Görsel Analog Skala (GAS) ve Gastrointestinal Semptom Derecelendirme Ölçeği (GSDÖ) uygulandı. Gruplar arası karşılaştırma bağımlı örneklem t-test ile analiz edildi. Ayrıca etki büyüklüğünün hesaplanması için Cohen’s d formülü uygulandı. Testler sonucunda kalp atım hızı (KAH), kadans, FTP (ortalama güç, W, W/kg), algılanan zorluk derecesi (AZD) ve GAS değerlerinde istatistiksel olarak anlamlı fark olmadığı tespit edildi (p>0,05). Ayrıca, SUP grubu lehine kadans değerlerinde düşük (0,34) ve GAS değerlerinde yüksek etki büyüklüğü (0,83) bulunurken, AZD değerlerinde PLA grubu lehine orta etki büyüklüğü (0,61) tespit edildi. GSDÖ bulgularında gruplar arasında anlamlı bir fark olmadığı tespit edildi (p>0,05). Sonuç olarak, çalışmamızda glutamin&kreatin kombine tüketiminin fonksiyonel eşik güç (FTP) ve performans üzerine akut etkisinin olmadığı belirlenmiştir. Bununla birlikte, glutamin&kreatin tüketiminin kas ağrılarına olumlu etki ettiği söylenebilir. Anahtar Kelimeler: Ergojenik Destek, Fonksiyonel Eşik Güç, Glutamin, Kreatin, Sporcu Beslenmesi. ABSTRACT: The aim of this study was to investigate the acute effect of the combined consumption of glutamine and creatine on the performance of cyclists. Eight licensed, active, and trained male cyclists (age: 25.85 ± 9.75 years; height: 174.71 ± 5.18 cm; body weight: 69.81 ± 7.16 kg; body mass index (BMI): 22.95 ± 2.97 kg/m2; sports age: 5.28 ± 2.28 years) voluntarily participated in this study. In a randomized, single-blind, and cross-over design, the cyclists were randomly divided into 2 groups and performed the functional threshold power (FTP) test by taking glutamine&creatine (SUP) or placebo (PLA) at a 48-hour interval. The Borg Scale, Visual Analog Scale (VAS), and Gastrointestinal Symptom Rating Scale (GSRS) were utilized at the end of the tests. Between-group comparisons were analyzed with paired sample t-tests. Cohen’s d formula was applied to calculate the effect size. No statistical significance was found in heart rate (HR), cadence, FTP (average power, W, W/kg), rating of perceived exertion (RPE), and VAS values (p>0.05). Also, while there was a small effect size in cadence (0.34) and a large effect size in VAS (0.83) in favor of the SUP group, a medium effect size (0.61) was observed in RPE in favor of the PLA group. In GSRS results, no significant difference was observed between the groups (p>0.05). In conclusion, it was determined that glutamine&creatine coingestion had no acute effect on functional threshold power (FTP) and performance. However, it can be said that glutamine & creatine consumption has a positive effect on muscle pain. Keywords: Creatine, Ergogenic Aid, Functional Threshold Power, Glutamine, Sports Nutrition.
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Sarcopenia, defined as the age-related decrease in muscle mass, strength and physical performance, is associated with reduced bone mass and elevated low-grade inflammation. From a healthy aging perspective, interventions which overcome sarcopenia are clinically relevant. Accumulating evidence suggests that exogenous creatine supplementation has the potential to increase aging muscle mass, muscle performance, and decrease the risk of falls and possibly attenuate inflammation and loss of bone mineral. Therefore, the purpose of this review is to: (1) summarize the effects of creatine supplementation, with and without resistance training, in aging adults and discuss possible mechanisms of action, (2) examine the effects of creatine on bone biology and risk of falls, (3) evaluate the potential anti-inflammatory effects of creatine and (4) determine the safety of creatine supplementation in aging adults.
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Prior resistance training (RT) recommendations and position stands have discussed variables that can be manipulated when producing RT interventions. However, one variable that has received little discussion is set end points (i.e. the end point of a set of repetitions). Set end points in RT are often considered to be proximity to momentary failure and are thought to be a primary variable determining effort in RT. Further, there has been ambiguity in use and definition of terminology that has created issues in interpretation of research findings. The purpose of this paper is to: 1) provide an overview of the ambiguity in historical terminology around set end points; 2) propose a clearer set of definitions related to set end points; and 3) highlight the issues created by poor terminology and definitions. It is hoped this might permit greater clarity in reporting, interpretation, and application of RT interventions for researchers and practitioners.
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The purpose of the present investigation was to examine potential gender-related differences in electromyographic (EMG) and mechanomyographic (MMG) responses during submaximal, concentric, isokinetic, forearm flexion muscle contractions. Twelve men and twelve women performed concentric peak torque trials prior to (pretest) and following (posttest) a fatiguing exercise bout that consisted of 50 submaximal (65% of concentric peak torque), concentric, isokinetic (60°·s), forearm flexion muscle contractions. Surface EMG and MMG signals were simultaneously recorded from the biceps brachii and brachioradialis muscles. There was a gender-related difference in the decline in absolute concentric peak torque for the men (23.8%) versus women (18.5%) that was eliminated when covaried for differences in pretest concentric peak torque values. During the fatiguing exercise bout, EMG amplitude (AMP) increased and EMG mean power frequency (MPF) decreased for both genders and muscles. There were, however, muscle- and gender-specific increases, decreases, and no changes for MMG AMP and MMG MPF. The gender-related difference for the posttest decline in concentric peak torque was associated with differences in muscle strength which may have resulted in greater blood flow occlusion in the men than the women. The muscles with the most pronounced fatigue-induced neuromuscular responses were the biceps brachii in men and the brachioradialis in women. These findings may be related to gender differences in the usage patterns of synergistic muscles during a fatiguing task.
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Objective: To investigate the effects of creatine supplementation and drop-set resistance training in untrained aging adults. Participants were randomized to one of two groups: Creatine (CR: n=14, 7 females, 7 males; 58.0±3.0yrs, 0.1g/kg/day of creatine+0.1g/kg/day of maltodextrin) or Placebo (PLA: n=17, 7females, 10 males; age: 57.6±5.0yrs, 0.2g/kg/day of maltodextrin) during 12weeks of drop-set resistance training (3days/week; 2 sets of leg press, chest press, hack squat and lat pull-down exercises performed to muscle fatigue at 80% baseline 1-repetition maximum [1-RM] immediately followed by repetitions to muscle fatigue at 30% baseline 1-RM). Methods: Prior to and following training and supplementation, assessments were made for body composition, muscle strength, muscle endurance, tasks of functionality, muscle protein catabolism and diet. Results: Drop-set resistance training improved muscle mass, muscle strength, muscle endurance and tasks of functionality (p<0.05). The addition of creatine to drop-set resistance training significantly increased body mass (p=0.002) and muscle mass (p=0.007) compared to placebo. Males on creatine increased muscle strength (lat pull-down only) to a greater extent than females on creatine (p=0.005). Creatine enabled males to resistance train at a greater capacity over time compared to males on placebo (p=0.049) and females on creatine (p=0.012). Males on creatine (p=0.019) and females on placebo (p=0.014) decreased 3-MH compared to females on creatine. Conclusions: The addition of creatine to drop-set resistance training augments the gains in muscle mass from resistance training alone. Creatine is more effective in untrained aging males compared to untrained aging females.