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TheBenefitsofExerciseWarm‐UponGripStrengthandFatigueTime
AlexFinn,AsiminaPappas,CamiloCampo,JoeHiggins,SethBraddock,RebeccaFrenz
Keywords:
BreathingRate(new)ExerciseEMGHeartRate(new)MuscleFatigue(new)PerformanceStrengthWarm‐Up(new)
Lab601
Group7
Abstract
Strengthandendurancearetwokeyfactorsinanyathlete’sabilitytoperform.This
experimentwasdesignedtomeasurethecorrelationbetweenanexercisewarmupand
gripstrengthandfatiguetime.Twogroups,acontrolandanexperimental,weretested.The
controlgroupsubjectsparticipatedintwoseparatesessionsoverthecourseofafew
weeks,neitherofwhichincludedanexercisewarmup.Theexperimentalgroupsubjects
participatedintwoseparatesessionsoverthecourseofafewweeks,thefirstofwhichwas
recordedasabaselinemeasurementandthesecondoccurredafterawarmupexercise.
Thepurposeoftheresearchgroup’sexperimentsistodeterminewhetherthereisa
positivecorrelationbetweenanexercisewarmupandanindividual’sstrengthand
endurance.
Introduction
Physicalfatigueisaloweredactualmuscularcontractileresponsecomparedtothe
anticipatedresponseofagivenstimulus(Fitts,1994).Thecausesoffatiguearenumerous;
althoughmanytheorieshavenotyetbeenproposed,itissuspectedthatanypointinthe
pathway‐‐fromspinalcordtomusclecell‐‐canleadtofatigue.Itissuspectedthatone
reasonforfatigueisareductionofneuraldrivetoworkingmusclecausedbya“spillover”
ofserotonin.Duringahighlevelofexercise,serotoninproductionincreases,causingitto
bind5‐HT1Areceptorsontheinitialsegmentofmotorneurons,andthus,inhibitingnerve
impulseinitiation(Coteletal.,2013).Similarly,anothercauseoffatigueistheinabilityofa
nervetomaintainahigh‐frequencysignalduringmaximummuscularexertion;thisfatigue
doesnotcausesoreness.Itcanbeovercomewithrepetitivetraininguntilthenerve
generatesmaximumcontractions(Robergs,2004).
Themostcommonmechanismsthoughttoexplainfatiguedealwiththemuscle
fiber;specifically,itisthoughtthatthedepletionofsubstratesortheaccumulationof
metabolicproductsinvolvedinmusclecontractionarethemainreasonsforfatigue.
DeficiencyinATP,creatinephosphateandglycogenreducesavailableenergy,hindering
contraction.Also,whenexerciseintensityincreases,moreATPisusedup,releasingmore
protons.TheincreasingneedforATPresultsintheneedforregenerationbynon‐
mitochondrialsources,furtherincreasingprotonrelease,causingacidosis(Robergs,2004).
Muscularfatiguecangreatlyaffectanathlete’sperformance;physicalandtechnical
abilitiesbecomeimpairedsincetechniqueandmotorskillexecutionisreduced.Decreased
throwingvelocities,kickingpower,mentalconcentration,andthrowingandshooting
accuracieshavebeenassociatedwithphysicalfatigue(Knickeretal.,2011).Understanding
somemechanismsinwhichfatiguecanbereducedoravoidedwouldgreatlybenefitnot
onlyprofessionalathletes,butalsoanyoneperformingphysicalactivity.
Extensiveresearchhasbeenconductedontheeffectsofwarmingupbeforeexercise
asitpertainstoincreasingthephysicalperformanceofathletes.Inastudythatassessed
theeffectsofwarminguponinjuryprevention,itwasfoundthatsoccerplayersincreased
theirstrengthandweremorelikelytopreventinjuryiftheywarmedupbeforehand.The
pre‐exercisewarm‐upincludedstrength,musclecontrol,balance,andrunningexercises
(Daneshjoo,2012).Similarly,anexperimenttoassesstheeffectsofadynamicwarm‐upon
powerandagilityperformancefoundthatstrengthandenduranceofthesubjectswho
incorporatedthedynamicwarm‐upimprovedincomparisontothosethatdidnot
(McMillianet.al,2006).Thewarm‐upsincorporatedintheseexperimentsproducedan
increasedbreathingrateandheartrate,andthesephysiologicalchangesresultinor
accompanyimprovedphysicalperformance.Anincreaseinbreathingrateduringexercise
leadstomoreoxygenintakebythebody,providingmoreoxygenformusclestowork
(Tatsuya,2004).Anincreasedheartrate,whichischaracterizedasmoreheartcontractions
perminute,increasestheamountofbloodthatcangettothemuscles,whichimproves
theirproductivity("BloodPressurevs.HeartRate,"2012).Thisalsohastodowiththe
amountofoxygenthatgetstothemusclesfromthelungs.Bothbreathingrateandheart
ratearerelated,andbothincreaseduringexercise.Theincreasesinthesevariablesarethe
presumedcausesofincreasesinstrengthandendurance,whichistherelationshipthatis
goingtobetestedinthisexperiment.
Theobjectofthisexperimentistodeterminehowmanipulatingtwovariables,heart
rateandbreathingrate,willaffectboththefatiguetimeandthemaximumgripstrengthof
thesubjects.However,theresultsofthisexperimentarenotintendedsolelyforthe
analysisofhandstrengthandfatiguetime—theresearchgroupintendstorelatethe
findingstooverallphysicalmuscularperformance.Withasuccessfulexperiment,the
researchgroupwillbeabletothenproposeanewhypothesis;thatanincreaseinheartrate
andbreathingratewillresultinanincreaseinoverallphysicalmuscularperformance.
Failuretorejectthehypotheseswillgivetheimplicationthatbywarmingupandelevating
anindividual’sheartrateandbreathingrate,theyarepreparingtoimprovetheirstrength
andendurance.Asidefrommeasuringgripstrengthandfatiguetime,theresearchgroup
willalsoobserveheartrateandrespiratoryrate.Manipulationofthesevariableswillbe
accomplishedthroughawarm‐upexerciseofbikingfor3minutes.
Thisstudywillbebasedontwohypotheses.Thefirsthypothesisisthatanexercise
warm‐up,definedbyanincreaseinheartrateandrespiratoryrate,willinduceasignificant
improvementingripfatiguetime.Thesecondhypothesisisthatanexercisewarm‐up,
definedbyanincreaseinheartrateandrespiratoryrate,willinduceasignificant
improvementingripstrength.
Methods
Inordertomeasurechangesinmusclefatigueandcontractilestrengthinducedafter
apre‐workoutwarm‐up,theresearchgroupfirstrecordedbasicinformationanddatafrom
eachparticipatingtestsubject.Participatingsubjectsweretakenfromthepoolofstudents
enrolledintheUniversityofWisconsin‐MadisonPhysiology435courseandincludedthe
researchgroupmembersaswell.Priortothecollectionofdataontheparticipants,a
consentformconcerningthedetailsofthestudywasgiventoparticipantstoreadandsign.
Theparticipantdatacollectionincludedbasicinformationabouteachsubjectsuch
astheirname,sex,age,weight,height,andhoursofphysicalactivityperweek,hoursof
sleep,breakfastconsumptionthemorningofthestudy,leftorrighthandedness,illnesses,
workoutstatus,alcoholandcaffeineconsumption,wristinjuries,andwhetherornotthe
participanthaspreviouslyusedanElectromyography(EMG)device.Thepurposeofthis
specificdatacollectionwastoprovidebehavioralorphysiologicalbasisforremovalof
statisticallydeterminedoutliers.
Oncethisinformationwascollected,theparticipantwasaskedtowearaBSL
RespiratoryEffortandaPulseOximeterinordertorecordtheirrestingbreathingrateand
restingheartrate,respectively.Therestingbreathingrateoftheparticipantwasrecorded
whiletheparticipantwascompletingtheirconsentformandquestionnaire.Toensurethat
theparticipantwasnotawareofwhentheirbreathingwasbeingmonitored,theywerenot
toldthattheirbreathingwasbeingrecorded.Theexperimentersalsodidnotspeakwith
theparticipantatthistime,sothatthebreathingratewouldnotbealteredbytheactionof
talking.Breathingratedatawasassessedbytakingtheaverageofthebreathsperminute
measuredforeveryinhale/exhalecycleina20‐secondtimeinterval.Theperiodsof
inhalationandexhalationwererepresented,respectively,byariseandfallofthegraph.To
calculatetheaveragebreathsperminute,theresearchgrouprecordedthevalues
designatedbythedistancebetweentroughsandusedthemtocalculatetheaverage
breathingrate.
ThePulseOximeterreading,whichmeasurednumberofheartbeatsperminute,
wasalsotakenandrecordedpriortotheuseoftheEMGdevice.Next,theparticipant
calibratedtheEMGdevicewithatwo‐secondsqueeze,whichwasimmediatelyfollowedby
theinvitationtosqueezetheEMGrecordingdevicewithalloftheirstrengthforaslongas
theycould.TheFatigueTimewasrecordedwhentheparticipant’sGripStrengthdropped
tohalfoftheirMaximumGripStrengthvalue,atwhichpointtheparticipantwastoldto
stopsqueezingandrelax.MaximumGripStrengthwasrecordedinkilogramsandFatigue
Timewasmeasuredinseconds.
Participantsfromthefirsttrialweresplitbysex,andeachsexwasthenassignedto
oneoftwogroupsbyrandomlydividingtheirconsentformsintoacontroland
experimentalpopulation.Thiswasaccomplishedbyshufflingtheconsentformsand
drawingthemoutofahat.Ofthethirteentotalmales,sixwereinthecontrolgroupand
sevenwereintheexperimentalgroup.Similarly,ofthefifteentotalfemales,eightwerein
thecontrolgroupandsevenwereintheexperimentalgroup.Theparticipantswereeach
calledbacktoperformanothertestaftertheircategorywasassigned.Theparticipants
werenotinformedofthereasonforthesecondtest,inanattempttoreducebias.
Participantsweretestedforthesecondtimeonetothreeweeksfollowingtheirinitialtest.
Again,eachparticipantwasaskedtofilloutthebasicinformationsurvey.Thecontrol
grouprepeatedtheinitialexperimentdescribedabove,inexactlythesamemanner.The
experimentalgroupperformedadifferentexperiment.
Theexperimentalgroup’sparticipants’heartrateandbreathingratewerefirst
measuredatrestwhilefillingoutthesamequestionnairesheetasthefirstweek.Then,the
participantswereplacedonastationarybike,whichconstitutedthepre‐workoutwarm‐up.
Theywereinstructedtopedalonthebikeforthreeminutes.Theparticipants’heartrates
andbreathingratesweremeasuredaftertheydismountedthebikeandweresittingdown.
Again,carewastakenbytheexperimentersnottoinfluencethebreathingrateofthe
participantswhentherecordingofthebreathingratewasbeingtaken(theBSLRespiratory
Effortwasnotremovedthroughouttheexperiment).
Afterthebreathingratewastaken,theparticipantswereaskedtorepeattheGrip
Strengthtest.DuringtheGripStrengthtest,GripStrengthandFatigueTimewererecorded
inthemannerpreviouslydescribed.Thetimeelapsedbetweentheendofthewarm‐upand
theGripStrengthtestwasminimized;itlastednomorethan2minutes.Thisreducedtime‐
lapseandensuredthatanyobservedeffectsonGripStrengthperformancewasduetothe
pre‐workoutwarm‐up.
StatisticalanalysiswasperformedusingMicrosoftExcel.Statisticalanalysis
comparedthetwopopulations,controlandexperimental,intermsofthechangein
individualfatiguetimeandthechangeinindividualgripforce.Thepercentchangein
individualfatiguetimewascalculatedbycomparingthevaluerecordedduringthesecond
seriesofmeasurementsfromthemeasurementrecordedatthefirstsession.Thesame
method,withtheappropriatedataset,wasusedtodeterminethepercentchangein
individualgripstrength.Eachdatasetwassubjectedtoaquantile‐quantileplotinorderto
determineifthedatawasnormallydistributed.Whenboththecontrolandexperimental
datasetsofthesamevariablewerefoundtobenormallydistributed,at‐testwas
performed.Thetypeoft‐testandthenumberoftailsweredeterminedbythestandard
deviationsandthecorrespondinghypothesis,respectively.Ap‐valuelessthan0.05was
consideredsignificant.
Furtherstatisticalanalysiswasperformedtotestforanyrelationshipsnotpredicted
andleftoutofthehypothesis.Linearregressionwasperformedinordertoobserve
relationshipsbetweenrespiratoryrate,heartrate,gripstrength,andfatiguetime.Data
pointsthreestandarddeviationsfromthemeanwereconsideredoutliersandomittedfrom
allfurtherstatisticalanalysis.
Materials
HandynamoSS25LA(BiopacSystems,Inc.,AeroCaminoGoleta,CA)
ElectromyographyII(BiopacSystems,Inc.,AeroCaminoGoleta,CA)
PulseOximeterModel9843(NoninMedical,Inc.,Minneapolis,MN)
BSLRespiratoryEffortXdcrSS5LB(BiopacSystems,Inc.,AeroCaminoGoleta,CA)
StationaryBicycle
SignaGel‐ElectrodeGel(BiopacSystemsInc.,Fairfield,NJ)
TheHandynamoSS25LAwasusedincooperationwiththeElectromyographyIIon
theBiopacprogramtomeasuregripstrengthinkilograms.ThePulseOximeterModel9843
wasusedtomeasureheartrate.Thedeviceworksbyhavingthesubjectplacetheirindex
fingerintoaslotthatisprogrammedtorecordtheheartrate.TheBSLRespiratoryEffort
XdcrSS5LBwasusedtomeasurebreathingrate.Thisdeviceconsistedofanelasticband
witharecordingunitthatwasplacedaroundthetorsoofthesubject.
Timeline
Week1&2Controlgroup/Week1ExperimentalGroup
Figure1–Themeasurementsthatweretakenfromparticipantsoveratimeperiodoffiveminutes;thisisaccordingtothecontroltrial.
Figure2–Themeasurementsthatweretakenfromparticipantsoveratimeperiodofsevenminutes;thisisaccordingtotheexperimentaltrial.Results
Overthetwoseparateoccasionsthatparticipantswereevaluated,statistical
analysisofthecontrolgroupreportedameanpercentchangeforthegripstrengthand
fatiguetimeof+3.0%and‐1.9%,respectively.Apositivemeanpercentchangeforgrip
strengthindicatesthatonaverage,thecontrolsubjectsshowedasmallincreaseingrip
strength.Anegativemeanpercentchangeinfatiguetimeindicatesthatonaverage,the
controlsubjectsshowedasmalldecreaseinfatiguetime.
Overthetwoseparateoccasionsthatparticipantswereevaluated,statistical
analysisoftheexperimentalgroupreportedameanpercentchangeforgripstrengthand
fatiguetimeof+23.3%and+42.7%.Apositivemeanchangeof23.3%forgripstrength
indicatesthatonaverage,theexperimentalgroupshowedadramaticincreaseingrip
strengthfromthebaselinemeasurementsrecordedinthefirstweektothemeasurements
recordedafterexerciseinthefollowingevaluation.Apositivemeanchangeof42.7%for
fatiguetimeindicatesthatonaverage,theexperimentalgroupshowedadramaticincrease
infatiguetimefromthebaselinemeasurementsrecordedinthefirstweektothe
measurementsrecordedafterexerciseinthefollowingevaluation.
Aonetailedtype2T‐Testcomparingthecontrolandexperimentalgroupsfor
fatiguetimereportedap‐valueof0.009404.Thisvalueindicatesthattheresultsare
statisticallysignificantandtheresearchgroupfailtorejectthefirsthypothesis,which
statesthatanexercisewarm‐up,definedbyanincreaseinheartrateandrespiratoryrate,
willinduceasignificantincreaseinfatiguetime.
Aonetailedtype2T‐Testcomparingthecontrolandexperimentalgroupsforgrip
strengthreportedap‐valueof0.002601.Thisvalueindicatesthattheresultsare
statisticallysignificantandtheresearchgroupfailtorejectthesecondhypothesis,which
statesthatanexercisewarm‐up,definedbyanincreaseinheartrateandrespiratoryrate,
willinduceasignificantincreaseingripstrength.
Graphsindicatingthebestindividualchangeforallvariablesforboththe
experimentalandcontrolsubjectsareshownbelow,alongwithgraphsindicatingthe
summaryofthemeanpercentchangeforallindividualsforboththeexperimentaland
controlsubjects.
Figure3–TwentyeightstudentsinPhysiology435wereseparatedintocontrolandexperimentalgroupsandtestedinaseriesofweeksfromFebruarytoApril2014.Thepercentincreaseinstrengthwascalculatedasthemeanofindividualchangesinstrengthfromweekonetoweektwo.Theexperimentalandcontrolgroupwereshowntobesignificantlydifferent(t‐test,pcalc>0.05).Errorbarsare+/‐onestandarddeviation.
Figure4–TwentyeightstudentsinPhysiology435wereseparatedintocontrolandexperimentalgroupsandtestedinaseriesofweeksfromFebruarytoApril2014.Thepercentincreaseinfatiguetimewascalculatedasthemeanofindividualchangesinfatiguetimefromweekonetoweektwo.Theexperimentalandcontrolgroupwereshowntobesignificantlydifferent(t‐test,pcalc>0.05).Errorbarsare+/‐onestandarddeviation.
Figure5–Valuesofweeklymeasurementsofanexperimentalindividual’sheartrate,breathingrate,gripstrength,andfatiguetime.
Figure6–Valuesofweeklymeasurementsofacontrolindividual’sheartrate,breathingrate,gripstrength,andfatiguetime.
Figure7–Percentchangeofweeklymeasurementsofanexperimentalindividual’sheartrate,breathingrate,gripstrength,andfatiguetime.
Figure8–Percentchangeofweeklymeasurementsofacontrolindividual’sheartrate,breathingrate,gripstrength,andfatiguetime.
Discussion
Theresultsfailedtodisproveeitherofthehypothesesbecause,asthep‐values
indicate,themaximumgripstrengthandfatiguetimeoftheparticipantsincreasedin
responsetothewarm‐up.Additionally,thecollectionofdatawassuccessfulbecauseofthe
efficiencyandconsistencyoftheresearchgroup’smethods.Thatis,theprotocolwas
consistentforeachparticipantinbothgroups.
Anumberofoutsideinfluencesmayhavecausedpotentialchangeswithinthe
experimentandthecollecteddata.Includedinthesepotentialinfluencesarethephysical
stateandwellbeingoftheparticipantsandtheplacementandmechanicalintegrityofthe
measuringdevices.Forexample,factorssuchastheamountofsleepobtainedbyeach
participant,iftheparticipantworkedoutintherecentpast,generalhealthstatus,and
overallphysicalfitnessoftheparticipantpriortoeachtestmayhaveaffectedtheamountof
forcetheyareabletoexertontheHandDynamometer.Inaddition,mechanicalfactorssuch
astheaccurateplacementoftheelectrodesfortheEMG,efficiencyofthemeasuring
devices,andcorrectplacementoftheBSLRespiratoryEffortcouldhavehadunprecedented
effectsonthedata.
Implicationsoftheresultscanbenefitpeoplelookingtoimprovetheirathletic
performance.Morespecifically,athleteslookingtoincreasetheirmaximumstrength
outputaswellasthetimeduringwhichthisstrengthisexertedshouldconsider
incorporatingasimilarwarm‐upintotheirworkoutroutine.Asthedatasuggests,
increasingheartrateandbreathingratewerebeneficialtotheparticipants'performance.
Althoughtheexactreasonsfortheparticipants’increasesinfatiguetimeandforceexerted
areunknown,possibleexplanationshaverisen.Mechanismssuchasaccumulationofacidic
wasteproducts,depletionofenergy,reductionofneuraldrivetoworkingmusclecausedby
aserotonin“spillover,”andtheinabilityofanervetomaintainahigh‐frequencysignal
wereallpossiblecausesoffatiguethattheresearchgroupmentionedintheintroduction.
Althoughtheinabilityofthenervetomaintainhigh‐frequencysignalingduringmaximum
muscularexertioncanbeacauseoffatigue,itshouldnotbethemechanismunderlyingthe
resultsinthisstudybecausenotenoughexercisewasperformedbythesubjectstochange
this.Itcanbethat,sincetheexperimentaldataafterthe3‐minutewarm‐upwascollected
afterspringbreak,participantsmayhaveworkedoutortrainedmore,andthatwasnot
controlledbythestudy.
Theimprovementinperformancecouldalsobeduetotheincreasedflowof
oxygenatedbloodtomuscle,duetoanincreaseinstrokevolumeinducedbythe
sympatheticnervoussystemwhichisachievedwhilewarmingup.Increaseinblood
temperatureresultingfromexerciseisalsocrucialtothereleaseofoxygentothetissuesas
impliedbytheoxygen‐hemoglobindissociationcurve.Increasedbloodflowcouldhave
clearedmetabolitebuild‐upassociatedwithfatigueinmusclefibers.Additionally,another
possibletheoryexplainingtheincreaseinstrengthandfatigue‐timewithwarm‐upcanbea
delayedadrenalglandinfluenceofthesympatheticnervoussystemonthebody.Warming
upforafewminutesbeforetheexperimentcouldhavegiventhesubjectsenoughtimefor
theepinephrinesecretedintothebloodstreamtoreachtargetorgans(Raff,Levitzky2011).
Althoughtheerrorproducedintheexperimentwasasminimizedaspossible,itwas
notabsent.Themainsourceoferrorinthisexperimentwashumanerror.Thebreathsper
minutewerecalculatedbyhandbytheexperimentersbecausetherewasnotasystemto
calculatethisonthecomputer.Thisledtovaryingresultsbasedonhoweachspecific
breathpeakwasmeasured,althoughcarewastakentobeaspreciseaspossible.An
additionalsourceofhumanerroroccurredwhiletheparticipantwasperformingthe
experiment.Iftheparticipantspokewhiletheirbreathingratewasbeingmeasuredthe
outcomeofbreathpeaksonthegraphgeneratedbytheBSLrespiratoryeffortwerealtered.
Speakingwiththeparticipantsduringthisparticulardatacollectionwasdiscouraged;
however,theparticipantsweresometimesspokento.Thiserrorcouldeasilybecorrected
byensuringsilenceduringthesubject’sbreathmeasurements.Toremovebias,careshould
betakeninthefuturetonotletthesubjectknowwhentheirbreathingrateisbeingtaken,
andtonotaltertheirresultsbytalkingtothem.Inaddition,someoftheparticipantswere
alreadyfatiguedfrompriorexperimentsinthedayatotherlabstations,thus,potentially
skewingthedata.Thiswasoutofthecontroloftheparticipantsandtheexperimenters.
ThefinalsourceofhumanerrorwastheplacementoftheelectrodesoftheEMG
Device.Eventhoughelectrodeswereplacedascloseaspossibletothedesignatedpositions
asindicatedbythemachine,humanerrorcouldhaveplayedaroleinputtingtheminless
thanidealplaces.Equipmentinaccuraciesalsooccurredthroughouttheexperiment.The
equipmentthatwasused(theexercisebike,theBSLRespiratoryEffort,PulseOximeter,
andEMGDevice)wasusuallyaccurate,butdidshowsomesignsofbeinginaccurate.
Ideally,morepreciseequipmentcouldbeusedifthereisameanstoattainit.
FutureDirection
Experimenterslookingtoconductasimilarstudyshouldincorporatethesame
sequenceofeventsforthecontrolandexperimentalprocedures.Theorderinwhichthe
datawascollectedallowedforminimalinfluencefromoutsidesources.Additionally,the
variablesthatconstitutedthepre‐workoutwarm‐upshouldbekeptthesame,astheseare
inaccordancewiththeliterature.
Futureexperimentscouldincludemoreexplicitpre‐workoutwarm‐up.For
example,insteadofhavingparticipantsbikeforthreeminutes,futureexperimentscan
haveparticipantsbikeforthreeminutesatapacethatwillincreasetheirheartrateby
50%.Thisallowsstrongercomparisonstobemadebetweenindividualsandthe
correlationbetweentheirincreasedbloodflowandmaximumstrengthoutput.Future
experimentscouldalsomeasuretheeffectsofincreasedoxygenintake,asthiswould
separatetheeffectsofthewarm‐upontheheartandonrespiration.Additionally,amore
precisecontrolwouldbetohavetheparticipantssitonthebikeforthreeminutes.This
wouldtakeintoaccounttheeffectsofsittingonthebike,holdingthehandlebars,etc.on
theirheartrateandbreathingrate.
Finally,experimenterslookingtorepeatthisstudycouldmeasuretheheartrateand
breathingrateoftheexperimentalgrouptenminutesaftertheydothewarm‐upin
additiontobeforethewarm‐up.Presumably,theparticipant’sheartrateandbreathingrate
wouldreturntotheirbaselinevaluestenminutesafterthewarm‐up.Thisallowsfor
confirmationoftheeffectsofthewarm‐upontheexperimentalresultsbyensuringthatthe
gripstrengthandfatiguetimeweremeasuredwhiletheparticipanthadanelevatedheart
rateandbreathingrate.
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