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RESEARCHARTICLEOpenAccessNutritionalbehaviorofcyclistsduringa24-hourteamrelayrace:afieldstudyreportRaúlBescós1*,FerranARodríguez1,XavierIglesias1,BeatKnechtle2,AdolfoBenítez1,MíchelMarina1,JosepMPadullés1,PriscilaTorrado1,JairoVazquez1andThomasRosemann2AbstractBackground:Informationaboutbehaviorofenergyintakeinultra-endurancecyclistsduringa24-hourteamrelayraceisscarce.
Thenutritionalstrategyduringsuchaneventisanimportantfactorwhichathletesshouldplancarefullybeforetherace.
Thepurposeofthisstudywastoexamineandcomparethenutritionalintakeofultra-endurancecyclistsduringa24-hourteamrelayracewiththecurrentnutritionalguidelinesforenduranceevents.
Additionally,weanalyzedtherelationshipamongthenutritionalandperformancevariables.
Methods:Usingaobservationaldesign,nutritionalintakeofeightmales(mean±SD:36.
7±4.
7years;71.
6±4.
9kg;174.
6±7.
3cm;BMI23.
5±0.
5kg/m2)participatingina24-hourteamrelaycyclingracewasassessed.
Allfoodandfluidintakebyathleteswereweighedandrecorded.
Additionally,distanceandspeedperformedbyeachriderwerealsorecorded.
Furthermore,beforetotherace,allsubjectscarriedoutanincrementalexercisetesttodeterminetwoheartrate-VO2regressionequationswhichwereusedtoestimatetheenergyexpenditure.
Results:Themeaningestionofmacronutrientsduringtheeventwas943±245g(13.
1±4.
0g/kg)ofcarbohydrates,174±146g(2.
4±1.
9g/kg)ofproteinsand107±56g(1.
5±0.
7g/kg)oflipids,respectively.
Thisamountofnutrientsreportedanaveragenutrientintakeof22.
8±8.
9MJwhichweresignificantlylowercomparedwithenergyexpenditure42.
9±6.
8MJ(P=0.
012).
Averagefluidconsumptioncorrespondedto10497±2654mL.
Meancaffeineingestionwas142±76mg.
Additionally,therewasnorelationshipbetweenthemainnutritionalvariables(i.
e.
energyintake,carbohydrates,proteins,fluidsandcaffeineingestion)andthemainperformancevariables(i.
e.
distanceandspeed).
Conclusions:A24-hourhourscyclingcompetitioninateamrelayformatelicitedhighenergydemandswhichwerenotcompensatedbyenergyintakeoftheathletesdespitethatdietaryconsumptionofmacronutrientsdidnotdiffertothenutritionalguidelinesforlongerevents.
Keywords:energybalance,ultra-endurance,macronutrientconsumption,hydration,bicycling,weigheddietaryrecord,descriptivestudyBackgroundUltra-endurancecompetitionsaredefinedasenduranceperformancesofmorethansixhoursofduration[1].
Traditionally,ultra-enduranceracesareheldassoloeventsinattemptstochallengethelimitsofhumanendurance.
However,theincreasedpopularityofthesecompetitionsinrecentyearshasledtodifferentformatsofparticipation,suchasteamrelayswithfourridersperteam[2].
Incomparisonwithsoloeventswhereathletesperformacontinuousexercise(>6hours)atameanintensityof~60%ofmaximumoxygenuptake(VO2max)[3],teamrelaycompetitionselicitintermittentexerciseatameanintensityabove75%ofVO2max[4,5].
Thenutritionalstrategyduringultra-enduranceeventsisanimportantfactorthatathletesshouldplancarefullybeforetherace.
Theamountandthesourceofenergyintake,fluidreplacement,aswellastheingestionofsti-mulantssuchascaffeineareimportantfactorsdirectlylinkedtosportperformanceinenduranceevents[6,7].
Inrelationwiththeenergydemands,severalstudieshave*Correspondence:raulbescos@gmail.
com1InstitutNacionald'EducacióFísicadeCatalunya,SportsSciencesResearchGroup,UniversitatdeBarcelona,SpainFulllistofauthorinformationisavailableattheendofthearticleBescósetal.
JournaloftheInternationalSocietyofSportsNutrition2012,9:3http://www.
jissn.
com/content/9/1/32012Bescósetal;licenseeBioMedCentralLtd.
ThisisanOpenAccessarticledistributedunderthetermsoftheCreativeCommonsAttributionLicense(http://creativecommons.
org/licenses/by/2.
0),whichpermitsunrestricteduse,distribution,andreproductioninanymedium,providedtheoriginalworkisproperlycited.
assessedthenutritionalrequirementsandbehaviorofcyclistsduringsoloevents[8-10].
However,thereisalackofinformationabouttheenergyrequirementsofathletescompetinginateamrelay.
Tothebestofourknowledge,onlyonestudyhasestimatedtheenergyexpenditureanddietaryintakeofcyclistsduringonecompetitionof24-hourinateamrelayformat[4].
Sur-prisingly,thisstudyshowedthatathletesingestedonly45%oftheirestimatedenergyexpenditureduringtherace.
Thesedataareinconcordancewithresultsreportedinsoloriders[8-10]despitethatinteamrelayevents,cyclistshaveaconsiderabletimetorecoverbetweentheboutsofexercise[4,5].
Thereisbroadevidencethatduringlongereventstheenergyreplacementshouldbemainlybasedonfoodrichincarbohydratesinceglycogenstoresinthebodyarelim-ited[11].
Thisfactcouldbeevenmoreimportantininter-mittenthigh-intensitycompetitionssuchasultra-enduranceteamrelayeventswhereathletesareperform-ingseveralboutsofexerciseathigherintensitywithlim-itedrecoveryperiodbetweenthem.
Whencarbohydratesarenotavailable,oravailableonlyinalimitedamount,theintensityofexercisemustbereducedtoalevelwheretheenergyrequirementcanbemetbyfatoxidation[7,12].
Themostrecentstudiesinlaboratoryconditionsindicatethattheadequateamountofcarbohydrateintaketoreducemuscleglycogendepletionandoptimizecarbohy-drateoxidationduringprolongedexerciseis~1.
5g/min[13-15].
Otherimportantissuesduringultra-enduranceeventsarebothfluidreplacementandcaffeineingestion.
Forinstance,itisknownthattheconsumptionofbeveragescontainingelectrolytesandcarbohydratesinaconcentra-tionof6-8%enhancesperformancecomparedtotheconsumptionofplainwater[16].
Consumptionofcaffeinehasbeenalsolinkedtoanimprovedexercisetolerance[17].
Dosesofbetween1.
5and3.
5mg/kghavebeenfoundtoimprovetime-trialperformancesinlaboratorystudies[18].
Themechanismstoexplainbenefitsofcaffeineinges-tionarebasedonanincreasedutilizationofplasmafreefattyacidsandreducedoxidationofmuscleglycogen[19],aswellasfavorablechangesinthecentralnervoussystem[20].
However,thereisalackofdataindicatingthehydra-tionpatternandcaffeineconsumptionfollowedbycyclistsduringultra-enduranceteamrelaycompetitions.
Accordingly,theprimaryaimsofthisstudywere(1)todescribethedietaryenergyintakeofultra-endurancecyclistsparticipatingina24-hourteamrelaycompeti-tion,(2)tocompareitwiththecurrentrecommendationsforlongerevents[6,7]and(3)toanalyzethecorrelationbetweenthenutritionalintakeandthevariablesofraceperformancesuchascompleteddistanceandreachedmeanspeed.
Wehypothesizedthatdietaryintakesofath-letescompetingina24-hourultra-endurancecyclingracediffertothecurrentnutritionalrecommendationsforlongerevents,thus,leadingtoahighenergydeficit.
Somefactorssuchasappetitesuppressionandgastro-intestinaldistresscanreducethedietaryintakeduringlongercompetitions.
Inaddition,thesedisturbancescanaffecttheperformanceofathletesleadingtoadecreaseinperformanceduringtherace.
Thisinformationisneededtoexpandthelimitedknowledgeofthenutri-tionalbehaviorofathletesduringthesetypesofevents,aswellastoreportnewinformationwhichcouldbeusefulfornutritionprofessionalstodesignanadequatenutri-tionalstrategyforathletes.
MethodsDesignofthestudyAnobservationalfieldstudyatthe24-hourcycleraceofBarcelona(Spain)wasusedforthisresearch.
Thecompeti-tionstartedat19:00hrsandconsistedofcompletingthemaximumdistancepossibleduringthe24-hourperiod,onaclosedroadcircuitof3,790metersinlength,and60metersofaltitudeperlap.
Withinthecircuit,alltheath-leteshadaboxwheretheyingestedfoodandperformedtheirrelays.
Thetimeandaveragespeedofeachcyclistwasrecordedoncompletionofeachlap.
Thestrategycho-senbytheathletesduringtheracewasuptothemwhereeveryteamdecidedtheorderanddurationoftheeffort.
Theaveragetemperatureduringthewholeeventwas~27.
5°C(range:24.
6-31.
0)andrelativehumiditywasat~53.
9%(range:33.
0-72.
0).
Themeanvelocityofwindwasat~1.
7m/s(range:0.
6-3.
0).
SubjectsAtotalofeightexperienced,non-professional,maleath-letes(6cyclistsand2triathletes),voluntarilyparticipatedinthisstudy(seeTable1).
Theathleteswerecontactedbytheresearchersviaphonebetweentwoandthreeweeksbeforetherace.
Thisracewasthefirstexperienceinanultra-enduranceteamrelaycyclingeventforallathletes.
Thesubjectshad12.
9±8.
8yearsofexperienceinendur-anceevents,andtheiraverageweeklytrainingvolumewasfrom15hoursuptoamaximumof30hours,withatotalvolumebetween800and1,000hoursperyear.
TheywereallmembersoftheSpanishCyclingorTriathlonFedera-tionsand,uptothestartofthestudy,reportednorelatedmedicalillnesses.
Allthesubjectspassedamedicalexami-nationandgavetheirinformedwrittenconsent,approvedbytheEthicsCommitteeoftheCatalonianSportsCouncil,priortotheirparticipation.
PreliminarytestingOneweekpriortothecompetition,allourathletesreportedtoaphysiologylaboratorytoperformanincrementalVO2maxtestundercontrolledconditions(22±1°C,40-60%relativehumidity,760-770mmHgbarometricBescósetal.
JournaloftheInternationalSocietyofSportsNutrition2012,9:3http://www.
jissn.
com/content/9/1/3Page2of11pressure).
Theywereaskedtorefrainfromcaffeine,alcoholandheavyexerciseonthedaybeforethetests,andtoreporttothelaboratoryatleasttwohoursafterhavingeaten.
Anincrementaltestwasperformedonanelectronicallybrakedcycleergometer(ExcaliburSport,Lode,TheNetherlands)modifiedwithclip-onpedals.
Theexerciseprotocolstartedat25watts(W)andwasincreasedby25Weveryminuteuntilvoluntaryexhaustion.
Thepedalingcadencewasindi-viduallychosenwithintherangeof70-100revolutionsperminute(rpm).
Duringthetest,oxygenuptake(VO2),min-uteventilation(VE),carbondioxideproduction(VCO2)andrespiratoryexchangeratio(RER)weremeasured,breath-by-breath,usingacomputerizedgasanalyzer(CosmedQuarkPFT-Ergo,Italy).
Beforeeachtest,theambientconditionsweremeasuredandthegasanalyzersandinspiratoryflowmeterwerecalibratedusinghigh-preci-sioncalibrationgases(16.
00±0.
01%O2and5.
00±0.
01%CO2,ScottMedicalProducts,USA).
Respiratorydatawereaveragedat30sintervalstodetermineVO2maxtakenasthehighestaveragevalue.
Theventilatorythreshold(VT)andtherespiratorycompensationpoint(RCP)weremea-suredbythreeindependentreviewersaccordingtomethodsdescribedbyWassermanetal.
[21].
Inaddition,heartratewascontinuouslyrecordedusingaportableheartratemonitor(PolarRS800SD,Finland).
Heartratedatawereaveragedat10sintervalsandthemaximumheartratewasdefinedastheheartrateachievedatthepointofexhaustion.
NutritionaldataAfterthetestalltheathletesreceivednutritionalguidelinesandwereencouragedtofollowahighcarbohydratedietduringthethreedayspriortothecompetitioninordertooptimizetheirglycogenreplenishment.
However,duringthecompetition,therewerenoconstraintsandthenutri-tionalpatternwasprogrammedbythecycliststhemselves.
Furthermore,theyreceivednodirectinstructionsfromtheinvestigatorsduringtheevent.
Seventrainedinvestigatorsweredividedamongtheboxesweighingandrecordingallthefoodandfluidingestedbyeachparticipantduringtherecoveryperiods.
Toweighallthefood,weusedtwodigitalscales(Soehnle8020,Spain)withaprecisionof1gincre-mentsupto1kgand2gbetween1and2kg.
Duringtherace,itwasforbiddentoprovidetotheathletesfoodandfluidsinanypointofthecircuitwiththeexceptionofthebox.
Allthefoodandfluidsthatcyclistsconsumedbeforeeveryrelaywereweighedandrecordedbytheresearchers.
Immediatelyaftereveryrelay,foodandfluidswereweighedandrecordedbytheresearchersagain.
Thedifferenceinweightwasconsideredastheamountoffoodandfluidsingestedbythecyclistsduringexercise.
Thetypeoffoodandfluidsofsportproductssuchasenergybarsandgelsingestedbythecyclistsweredescribedandrecordedusingthelabelsoftheproducts.
Informationderivedfrompre-paredfoodssuchaspasta,riceorsandwichwasprovidedaskingtheformofpreparation,directly,tothecyclists.
Thenutritionaldatawasanalyzedfornutrientcompositionusingnutritionalsoftware.
Toguaranteeamoreaccurateconversionofenergyandnutrientintakes,weusedadata-baseoffoodfromthecountrywherethestudywascarriedout(CESNID1.
0,BarcelonaUniversity,Spain).
Informa-tionaboutthenutritionalcontentoffoodnotavailableinthecomputerprogramwasobtainedfromthemanufac-turer.
Wedividedtheingestionofenergyderivedfromsolidandfluidfood(i.
e.
classifiedasproductsthatdidnotneedmastication).
Eachsubjectwasweighed30minutespriortotherace,aftereverycyclesessionandimmediatelyafterfin-ishingthecompetition.
Thesubjectswerealwaysweighedinclothing,shoesandbicyclehelmetsinordertofacilitatethecollectionoftheresearchdataduringtheevent.
Weightsweremeasuredoncalibratedscalesplacedonahardlevelsurface.
LoadofexerciseandenergyexpenditureDuringthewholecompetition,theheartratewascon-tinuouslymonitoredbeat-by-beatusingportableheartratemonitors(PolarRS800SD,Finland).
Later,allheartTable1PhysicalandphysiologicalcharacteristicsofthesubjectsSubjects12345678M±SDAge(years)34.
439.
729.
638.
343.
339.
831.
037.
536.
7±4.
7Height(cm)167.
0172.
4189.
1165.
1177.
6173.
5176.
0176.
0174.
6±7.
3Bodymass(kg)65.
368.
979.
965.
773.
974.
572.
572.
471.
6±4.
9BMI(kg·m2)23.
423.
222.
324.
123.
424.
723.
423.
423.
5±0.
5Bodyfat(%)9.
510.
89.
711.
19.
210.
49.
810.
610.
1±0.
7VO2peak(mL·kg-1·min-1)70.
271.
962.
553.
169.
156.
474.
769.
266.
4±6.
8HRmax(bpm)184165177165178174176176174±9VT(%HRmax)727475837477808577±5RCP(%HRmax)918990899189909290±1Wpeak(W·kg-1)6.
16.
26.
35.
76.
46.
05.
55.
96.
0±0.
3BMI:bodymassindex;VO2peak:peakofoxygenuptake;HRmax:maximumheartrate;VT:ventilatorythresholdexpressedas%ofHRmax;RCP:respiratorycompensationpointexpressedas%ofthemaximumheartrate;Wpeak:peakofpower.
Bescósetal.
JournaloftheInternationalSocietyofSportsNutrition2012,9:3http://www.
jissn.
com/content/9/1/3Page3of11ratedatawereaveragedat10sintervals.
Inordertoestablishareferenceforheartrate,weidentifiedthreezonesofphysicalexertionbasedontheVTandtheRCP:zoneI,belowtotheVT;zoneII,betweenVTandRCP;andzoneIII,aboveRCP.
Inaddition,toestimatethetotalworkloadofexerciseperformedbysubjectsweusedthetrainingimpulse(TRIMP)methodbyFosteretal.
[22].
TocalculateTRIMP,thescoreforeachheartratezonewascomputedbymultiplyingtheaccumulateddurationinthiszonebyamultiplierforthisparticularphase,e.
g.
1mininzoneIwasgivenscoreof1TRIMP(1*1),1mininzoneIIwasgivenascoreof2TRIMP(1*2),and1mininzoneIIIwasgivenascoreof3TRIMP(1*3).
ThetotalTRIMPscorewasobtainedbysummatingtheresultsofthethreezones[(minofzoneIHR[VT-RCP]*3)].
Toestimateenergyexpenditureduringtherace,theindividuallyderivedlinearrelationshipbetweenheartrateandVO2wasusedtoestimatetheoxygencostduringtheworkefforts(r2=0.
988±0.
005).
Twodifferentindividua-lizedequationswereestablished:1)alinearregressionequationforracingtimewhichwasderivedfromdatadur-ingtheincrementalexercisetest.
Weusedanenergyequivalentofoxygenbasedonthemeanintensityduringracingtime(i.
e.
thenon-proteinenergyequivalentcorre-spondingtomeanheartrateduringtheworkefforts).
Thisvaluewas,onaverage,0.
02MJ/LO2(4.
970±0.
048kcal/LO2),correspondingtoaRERof0.
941±0.
057[23].
2)AsingleexponentialequationbestfittedtoVO2andheartratewastakenduringtherecoveryperiodofthecycleerg-ometertest(r2=0.
912±0.
015).
Anenergyequivalentof0.
02MJ/LO2(4.
825kcal/LO2)wasused,assumingaRERof0.
82[23].
Therationaleforourapproachwasthatath-letesperformedboutsofexerciseinwhichtheheartrate-VO2relationshipcanbeassumedtobelinear,interspersedwithperiodsofrecoveryandrest,duringwhichtheheartrate-VO2relationshipbecomesnonlinear[24].
StatisticalanalysesDataarepresentedasindividualvaluesandmeans±SD.
Anon-parametricWilcoxontestwasusedtocomparetheenergybalanceandchangesinbodymassandexerciseintensityduringtheevent.
Inaddition,differencesbetweennutritionaldataduringthefirst(1900h-0700h)andthesecond(0700h-1900h)12hourperiodwereassessed.
Themainnutritionalvariables(i.
e.
energy,carbohydrates,proteins,fats,fluid,sodiumandcaffeine)werecorrelatedtospeedanddistancecompletedinabsolute(i.
e.
km;km/h)andrelative(i.
e.
%ofdecreaseofdistanceandspeed)valuesusingSpearman'srankcorrelationanalysis.
Inaddi-tion,fluidandsodiumconsumptionwasrelatedtobodyweightloss.
Non-parametricmethodswereapplied,asnotallparameterswereideallynormallydistributed.
Forallstatisticaltests,thesignificancelevelwassettoP800),whichwassignificantlyabovetodatareportedinelitecyclistsduringhighmountainstagesoftheTourdeFrance(~600TRIMP)[25],inducedahigherenergyexpenditure.
Thus,theseresultsconfirmedpartiallyourpreliminaryhypothesesandwereinagreementwithtwopreviousinvestigationsshowingthat,likesoloevents,ahighenergydeficitiscommoninateamrelayformateventsdespitethatathleteshaveconsiderabletimetorecoverbetweenboutsofexercise[4,26].
Oneexplana-tionforthiseffecthasbeenrelatedwithappetitesup-pressionsinceitisknownthatlongerexerciseinducesasuppressionofacylatedghrelininhumans[27].
GhrelinisanaminoacidpeptidehormonesecretedprimarilyfromcellswithinthestomachandithasbeensuggestedTable4Fluid,sodiumandcaffeineintakeandbodymasslossduringtheevent.
Subjects12345678Mean±SDFluidintakeRacingtime(mL/h)9238218548889118411110905907±90Recoverytime(mL/h)29135294283522316261163285±128Total(mL)111851129371069850158311053510480769910497±2654SodiumFluids(mg)9118975187673,3211,6826787381189±929Solids(mg)24662240981158364241357402760733144±2128Total(mg)337731371499235097453039470568114333±2714Bodymassloss(kg)2.
81.
41.
32.
52.
33.
00.
83.
23.
0±1.
3Caffeine(mg/kg)2.
02.
72.
41.
23.
40.
12.
51.
52.
0±1.
0Table3Macronutrientintakeduringtheevent.
Subjects12345678Mean±SDCarbohydratesSolids(g)284392290252695323668378533±175Fluids(g)538533442566889574456268410±174Total(g)82292573281815848971124647943±295g/kga12.
413.
59.
412.
321.
411.
915.
28.
813.
1±4.
0g/minb2.
062.
551.
912.
703.
122.
663.
772.
112.
61±0.
62%c77.
380.
276.
681.
462.
664.
867.
059.
371.
1±8.
7ProteinSolids(g)62664137262146126128109±75Fluids(g)352535332458060865±76Total(g)97917669507226186136174±146g/kg1.
51.
31.
01.
06.
93.
02.
51.
92.
4±1.
9%9.
28.
08.
16.
920.
216.
111.
212.
711.
5±4.
6RatioCHO:P(g)d8.
510.
29.
611.
93.
14.
06.
04.
77.
2±3.
2LipidsSolids(g)475248371599114213188±49Fluids(g)17101715422522519±11Total(g)64626452201116164136107±56g/kg1.
00.
90.
80.
82.
71.
62.
31.
91.
5±0.
7%13.
712.
215.
311.
818.
018.
622.
228.
317.
4±5.
6aRatiobetweentotalmacronutrientintake(g)andbodymass(kg)atthebeginningoftheevent.
bRatiobetweentotalcarbohydrateintake(g)andtotalracingtime(min)cPercentageofthetotalenergyintakedRatioCHO:P(g):Ratiooftotalgramsofcarbohydrateintakeinrelationtototalgramsofproteinduringtheevent.
Bescósetal.
JournaloftheInternationalSocietyofSportsNutrition2012,9:3http://www.
jissn.
com/content/9/1/3Page6of11tohaveanorexigenicfunction(i.
e.
appetitestimulating)[27].
MacronutrientsintakeTherecommendedamountofcarbohydrateintakeduringlongerexercisetooptimizeoxidationrateshavebeenreportedasbetween1.
0to1.
5g/min[15].
Thisrecom-mendationcouldbealsousefultoimproveglycogenreplenishmentduringthefirst4hoursafterexercise[28].
Inthecurrentstudy,themeancarbohydrateintakeinrela-tiontototalracingtime(2.
61±0.
62g/min)wassubstan-tiallyabovethesevalues.
Moreover,therelativeamountofcarbohydrateintakebycyclistswasequivalentto13.
1±4.
0g/kgofbodymass.
Thisdatareflectstherecommenda-tionsforextremelyprolongedandintenseexercise(10-12g/kgofbodymass/day)[11].
Thesefindingsshowthatultra-enduranceathletescompetinginteamrelayformatcanreachtheconsumptionofcarbohydrateswhichhasbeensuggestedinalaboratorystudytooptimizecarbohy-drateoxidation[13].
Thisfactisveryimportantinultra-enduranceteamrelayevents,sinceathletescanperformmorethan80%ofracingtimeatintensitiescorrespondingtozoneIIandIIIofHRmax(Table2).
Itisknownthatthispatternofexerciseelicitsanimportantoxidationofcarbo-hydratesasamainfuelformusclecontraction[12].
Nevertheless,notonlyistheamountofcarbohydratesimportant,itshouldbealsopaidattentiononotherfactorsrelatingtothelimitationsofcarbohydrateabsorption.
Thefeedingschedule,particlesize,mealtemperature,osmolal-ityandexerciseintensitydeterminethegastricemptyingandabsorptionintheduodenum[29].
Forinstance,somestudieshavedemonstratedthatahomogenizedfluidmeal,richincarbohydrates,emptiessubstantiallyfasterthananequivalentsolidmeal[29,30].
However,inlongerevents,solidfoodwillsatisfyanathlete'shungerandallowformorevariation,whichcanalsohelptointakeadequateamountsofcarbohydrates[1].
Inthisstudythesourceofenergywasbalancedbetweensolids(2,877±1,355kcal)andfluids(2,560±1,074),respectively.
Inaddition,thereisevidencethatduringhigh-intensityexercise(>80%VO2max)areducedbloodflowtothegutmayresultinadecreasedabsorptionofbothglucoseandwater[31].
Inthecurrentstudy,twocyclistsevidencedgastro-intestinaldisturbancesrelatedtonausea,abdominalcrampsanddiarrheaduringthelasthoursoftheevent.
Interestingly,bothcyclistsperformedrelaysathighinten-sitycomparedwiththeothercyclists(subject'snumber4and8inTable2).
Takinginaccountthatbloodflowtothegutdecreasesinproportiontotheexerciseintensityandgastro-intestinalproblemsaremorelikelytooccurwhentheexerciseintensityisincreased[23],thisfactcouldbeanexplanationfortheoccurrenceofthesepro-blems.
However,thisisonlyspeculationandwecannotFigure2Mainfluidsusedforhydrationandtheiraverageconsumptionduringtheevent.
Table5Energybalanceduringtheevent.
Subjects12345678Mean±SDEIduringracingtime(MJ)aFluids2.
53.
13.
12.
65.
94.
73.
73.
93.
7±1.
1EIduringrecoverytime(MJ)Solids7.
69.
67.
66.
222.
011.
318.
713.
412.
1±5.
7Fluids7.
76.
65.
48.
014.
77.
15.
70.
97.
0±3.
8TotalEnergyIntake17.
819.
316.
116.
842.
623.
128.
118.
222.
8±8.
9Energyexpenditure(MJ)Racingtime32.
630.
134.
322.
140.
125.
522.
522.
828.
8±6.
6Recoverytime13.
413.
920.
013.
09.
414.
214.
515.
614.
3±2.
9TotalEnergyExpenditure46.
044.
054.
335.
149.
539.
736.
038.
442.
9±6.
8*EnergyDeficit(MJ)-28.
2-24.
7-38.
2-18.
3-6.
9-16.
6-7.
9-20.
2-20.
1±10.
4EI:EEb0.
390.
440.
300.
480.
860.
580.
760.
470.
54±0.
19aEnergyintakebRatiobetweenenergyintakeandenergyexpenditure.
*Statisticaldifference(P75%ofVO2max).
Thispatternofexercisestimulatesanimportantconsumptionofcarbohydratestosupplyenergyformusclecontraction.
Thisstudyshowsthattheseultra-enduranceathleteswereabletoconsumelargeamountofcarbohydratesinafieldcompetitionwhichwasinaccordancewithdataobtainedinlabora-torystudiesinordertooptimizecarbohydrateoxidationduringexercise.
However,despiteofthisfactwefoundanincreasedenergydeficitthroughouttherace.
Thisfindingindicatesthatthenutritionalpatternfollowedthedaysbeforetothecompetitioncouldbeeven,oratleast,asimportantthatthedietarystrategyduringtheevent.
Inaddition,althoughproteiningestionbyathleteswasinaccordancewiththecurrentrecommendationsforathletes,ithasbeensuggestedthatcarbohydrate/proteinratioof4:1canenhanceseveralmetabolicpro-cessessuchasglycogenrecovery,proteinbalanceandtissuerepairwhichcanaffecttheoverallperformance.
Nevertheless,whiletheaccomplishmentofthisratiocouldinducethesebenefitsandreducetheenergydefi-cititisunknownwhetherathletescantoleratehighpro-teiningestionandperformhighintensityexercisewithoutgastro-intestinaldisturbances.
Toavoidtheseproblems,itisveryrecommendablethatathletesper-formanutritionaltrainingbeforetotheeventingestingsmallandfrequentamountsofmacronutrientsandfluidsduringtrainingsessions.
Thistrainingmayenhancetheresponseofthedigestivesystemduringultra-enduranceeventsandreducetheriskofgastro-intestinaldistressduringlongereventsinhardenviron-mentconditions.
AcknowledgementsThepresentstudywasfundedbytheNationalInstituteofPhysicalEducation(INEFC)andbytheUniversityofZürich(Switzerland).
TheauthorsBescósetal.
JournaloftheInternationalSocietyofSportsNutrition2012,9:3http://www.
jissn.
com/content/9/1/3Page9of11gratefullyacknowledgetheparticipationoftheathletesinthisstudyandthegeneroussupportofPolarIbérica(Spain),RPMEvents,andResearchGroupofAppliedNutrition,DepartmentofNutritionandBromatology(UniversityofBarcelona).
WeareindebtedtoDaveClampforhiseditorialassistance.
WewouldalsoliketothankVíctorCerveraforhistechnicalsupport.
Authordetails1InstitutNacionald'EducacióFísicadeCatalunya,SportsSciencesResearchGroup,UniversitatdeBarcelona,Spain.
2InstituteofGeneralPracticeandforHealthServicesResearch,UniversityofZurich,Switzerland.
Authors'contributionsRB,participatedinthedesignofthestudy,managedthedatacollectionprocess,conductedtheanalysisanddraftedthemanuscript.
FRandXI,participatedinthedesignofthestudyandmanagedthedatacollectionprocess.
AB,MM,JP,PTandJVparticipatedinthedatacollectionprocess.
BKandTRsupervisedtheanalysesofdataandhelpedtodraftthemanuscript.
Allauthorsreadandapprovedthefinalmanuscript.
CompetinginterestsTheauthorsdeclarethattheyhavenocompetinginterests.
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