Exercise Physiology, Cognitive Function, and Physiologic Alterations in Extreme Conditions

107 Pages·2015·10.12 MB·English

BioMed Research International
Exercise Physiology, Cognitive
Function, and Physiologic
Alterations in Extreme Conditions
Guest Editors: Ellen Glickman, Edward J. Ryan, and David Bellar
Exercise Physiology, Cognitive Function,
and Physiologic Alterations in Extreme
Conditions
BioMed Research International
Exercise Physiology, Cognitive Function,
and Physiologic Alterations in Extreme
Conditions
Guest Editors: Ellen L. Glickman, Edward J. Ryan,
and David Bellar
Copyright©2015HindawiPublishingCorporation.Allrightsreserved.
Thisisaspecialissuepublishedin“BioMedResearchInternational.”AllarticlesareopenaccessarticlesdistributedundertheCreative
CommonsAttributionLicense,whichpermitsunrestricteduse,distribution,andreproductioninanymedium,providedtheoriginal
workisproperlycited.
Contents
ExercisePhysiology,CognitiveFunction,andPhysiologicAlterationsinExtremeConditions,
EllenL.Glickman,EdwardJ.Ryan,andDavidBellar
Volume2015,ArticleID359325,1page
PreservationofCognitivePerformancewithAgeduringExertionalHeatStressunderLowandHighAir
Velocity,HeatherE.WrightBeatty,JocelynM.Keillor,StephenG.Hardcastle,PierreBoulay,
andGlenP.Kenny
Volume2015,ArticleID619103,10pages
HumanMonocyteHeatShockProtein72ResponsestoAcuteHypoxicExerciseafter3DaysofExercise
HeatAcclimation,BenJ.Lee,RichardW.A.Mackenzie,ValerieCox,RobS.James,andCharlesD.Thake
Volume2015,ArticleID849809,15pages
CardiopulmonaryResponsetoExerciseinCOPDandOverweightPatients:Relationshipbetween
UnloadedCyclingandMaximalOxygenUptakeProfiles,AbdoulayeBa,FabienneBrégeon,
StéphaneDelliaux,FallouCissé,AbdoulayeSamb,andYvesJammes
Volume2015,ArticleID378469,7pages
TheEffectsofMetabolicWorkRateandAmbientEnvironmentonPhysiologicalToleranceTimesWhile
WearingExplosiveandChemicalPersonalProtectiveEquipment,JosephT.Costello,KellyL.Stewart,
andIanB.Stewart
Volume2015,ArticleID857536,7pages
TheEffectsofColdandLowerBodyNegativePressureonCardiovascularHomeostasis,DavidJ.Kean,
CoreyA.Peacock,GabrielJ.Sanders,JohnMcDaniel,LisaA.C.Colvin,andEllenL.Glickman
Volume2015,ArticleID728145,6pages
ExhaustiveExerciseAttenuatestheNeurovascularCouplingbyBluntingthePressorResponsetoVisual
Stimulation,YujiYamaguchi,TsukasaIkemura,andNaoyukiHayashi
Volume2015,ArticleID671063,6pages
PostexerciseImpactofIce-ColdWaterBathontheOxidant-AntioxidantBalanceinHealthyMen,
PawełSutkowy,AlinaWoźniak,TomaszBoraczyński,CelestynaMila-Kierzenkowska,
andMichałBoraczyński
Volume2015,ArticleID706141,8pages
SingleWhole-BodyCryostimulationProcedureversusSingleDrySaunaBath:Comparisonof
OxidativeImpactonHealthyMaleVolunteers,PawełSutkowy,AlinaWoźniak,andPawełRajewski
Volume2015,ArticleID406353,6pages
PhysiologicalandSelectiveAttentionDemandsduringanInternationalRallyMotorSportEvent,
AnthonyP.TurnerandHughRichards
Volume2015,ArticleID638659,7pages
ChangesinBiochemical,Strength,Flexibility,andAerobicCapacityParametersaftera1700km
UltraenduranceCyclingRace,VicenteJavierClemente-Suarez
Volume2014,ArticleID602620,8pages
ProlongedSleepDeprivationandContinuousExercise:EffectsonMelatonin,TympanicTemperature,
andCognitiveFunction,GreggoryR.Davis,CoreyE.Etheredge,LenaMarcus,andDavidBellar
Volume2014,ArticleID781863,6pages
AnthropometricCharacteristicsandSexInfluenceMagnitudeofSkinCoolingfollowingExposureto
WholeBodyCryotherapy,L.E.Hammond,S.Cuttell,P.Nunley,andJ.Meyler
Volume2014,ArticleID628724,7pages
EffectsofaMealontheHemorheologicResponsestoExerciseinYoungMales,JanBilski,AnetaTeległów,
JanuszPokorski,JacekNitecki,JoannaPokorska,EwaNitecka,AnnaMarchewka,ZbigniewDąbrowski,
andJakubMarchewka
Volume2014,ArticleID862968,7pages
Hindawi Publishing Corporation
BioMed Research International
Volume 2015, Article ID 359325, 1 page
http://dx.doi.org/10.1155/2015/359325
Editorial
Exercise Physiology, Cognitive Function, and Physiologic
Alterations in Extreme Conditions
EllenGlickman,1EdwardJ.Ryan,2andDavidBellar3
1SchoolofHealthScience,ExercisePhysiology,KentStateUniversity,Kent,OH44242,USA
2ExerciseScience,ChathamUniversity,Pittsburgh,PA15232,USA
3SchoolofKinesiology,UniversityofLouisiana-Lafayette,Lafayette,LA70506,USA
CorrespondenceshouldbeaddressedtoEllenGlickman;[email protected]
Received27January2015;Accepted27January2015
Copyright©2015EllenGlickmanetal.ThisisanopenaccessarticledistributedundertheCreativeCommonsAttributionLicense,
whichpermitsunrestricteduse,distribution,andreproductioninanymedium,providedtheoriginalworkisproperlycited.
Exercise physiology is a heterogeneous field of study that at rest and during exercise. While military personnel are
includes a broad array of disciplines evaluating the impact oftendeployedtoareasoflowbarometricpressure,research
of physical stressors on the physiology of man. While man has also been conducted to better understand the effects of
is exposed to a variety of environmental conditions, it is hypoxiaoncognitivefunction.
imperative that exercise physiologists elucidate how the We invited investigators to contribute original research
addedstressofaterrestrialextremeimpactsman’sthermal, articlesaswellasreviewarticlesthatwillstimulatethecon-
metabolic, and cognitive abilities. Research regarding envi- tinuingeffortstounderstandexercisephysiologyinambient
ronmental extremes and exercise will enhance our under- and extreme environmental conditions. Further research in
standing of how to safely compete athletically, navigate in theseareaswillallowforbetterprecautionaryandtreatment
unfamiliarlocations,andaidmilitarypersonnelduringexpo- guidelinesinoccupationalandathleticsettings.
suretoavarietyofnaturalsettings.
EllenGlickman
The physiologic, metabolic, and cognitive responses in
EdwardJ.Ryan
general are complex and differ between sexes, across the
DavidBellar
lifespan,andareimpactedbyheredity.Whenphysicalstress
is coupled with varied ambient conditions (environmental
stressors, i.e., heat, cold, altitude, hypoxia, and lower body
negative pressure), there may be dramatic shifts in physio-
logical and cognitive responses. Furthermore, this coupling
of stressors may present a limitation in man’s abilities to
maintainhomeostaticcontrolacrossmultipleorgansystems.
Such limitations may compromise safety and performance;
thusfurtherworkintheseareasiswarranted.
Throughcontrolledexperimentation,takingintoaccount
asmanyconfoundingfactorsaspossible(i.e.,gender,menses,
age,trainingstatus,circadianrhythm,anddiet),weevaluate
combined physiologic and cognitive responses to environ-
mentalandexercisestresses.Recently,therehasbeengrowing
concernforworkselucidatinghowheat/coldstressorsinflu-
ence blood flow, cognitive function, and thermoregulation
Hindawi Publishing Corporation
BioMed Research International
Volume 2015, Article ID 619103, 10 pages
http://dx.doi.org/10.1155/2015/619103
Research Article
Preservation of Cognitive Performance with Age during
Exertional Heat Stress under Low and High Air Velocity
HeatherE.WrightBeatty,1,2JocelynM.Keillor,2StephenG.Hardcastle,3
PierreBoulay,4andGlenP.Kenny1
1HumanandEnvironmentalPhysiologyResearchUnit,SchoolofHumanKinetics,FacultyofHealthSciences,UniversityofOttawa,
125UniversityPrivate,MontpetitHall,Room367,Ottawa,ON,CanadaK1N6N5
2FlightResearchLab,NationalResearchCouncilCanada,Ottawa,ON,CanadaK1A0R6
3CanmetMININGNaturalResourcesCanada,Sudbury,ON,CanadaP3E5P5
4FacultyofPhysicalEducationandSports,UniversityofSherbrooke,Sherbrooke,QC,CanadaJ1K2R1
CorrespondenceshouldbeaddressedtoGlenP.Kenny;[email protected]
Received15August2014;Accepted5November2014
AcademicEditor:EdwardJ.Ryan
Copyright©2015HeatherE.WrightBeattyetal. This is an open access article distributed under the Creative Commons
AttributionLicense,whichpermitsunrestricteduse,distribution,andreproductioninanymedium,providedtheoriginalworkis
properlycited.
Olderadultsmaybeatgreaterriskforoccupationalinjuriesgiventheirreducedcapacitytodissipateheat,leadingtogreaterthermal
strainandpotentiallycognitivedecrements.Purpose.Toexaminetheeffectsofageandincreasedairvelocity,duringexercisein
humidheat,oninformationprocessingandattention.Methods.Nineyoung(24±1years)and9older(59±1years)malescycled4×
∘
15min(separatedby15minrest)atafixedrateofheatproduction(400W)inhumidheat(35C,60%relativehumidity)under0.5
(low)and3.0(high)m⋅s−1airvelocitywearingcoveralls.Atrest,immediatelyfollowingexercise(endexercise),andafterthefinal
recovery,participantsperformedanabbreviatedpacedauditoryserialadditiontask(PASAT,2secpace).Results.PASATnumbers
ofcorrectresponsesatendexerciseweresimilarforyoung(low=49±3;high=51±3)andolder(low=46±5;high=47±4)males
andacrossairvelocityconditions,andwhenscoredrelativetoagenorms.Psychologicalsweating,oranincreasedsweatratewith
theadministrationofthePASAT,wasobservedinbothagegroupsinthehighcondition.Conclusion.Nosignificantdecrements
inattentionandspeededinformationprocessingwereobserved,withageoralteredairvelocity,followingintermittentexercisein
humidheat.
1.Introduction reports in the literature have proposed that they are due to
variances in the participant groups (e.g., hydration status,
Performingphysicallydemandingworkinhotenvironments levelofheatacclimatization,anddegreeofsleepdeprivation)
and/or while wearing protective clothing increases ther- and/orinthemethodology(e.g.,environmentalconditions,
mal strain, which has been associated with decrements in mode of exercise, and type of difficulty of cognitive test)
cognitive function, such as reduced short-term memory, between studies. Although cognitive performance has been
recall,anddiscrimination[1];reactiontime,reasoning,and examined during and following exercise in the heat, the
vigilance [2]; and arithmetic ability [3]. In some cases, analysisistypicallydoneusingeitherchangeinhydrationor
however,improvedcognitiveperformancehasbeenobserved exerciserate(e.g.,exerciseata%ofVO2peak,absolutework
duringshortdurationcontinuousaerobicexercise(i.e.,60% rate, or completion of predetermined work tasks) [1, 2, 7]
VO2peak,10minduration;choice-discrimination)[4],during astheindependentvariables.Inaddition,theabovestudies
intense exercise (i.e., at/above anaerobic threshold; short- were conducted in young, healthy, active individuals (some
termmemory)[5],andafterboutsofcontinuousexerciseof middle-agedparticipantsinHecklerandCroce[6]).Thus,no
20and40mininduration(i.e.,70%VO2peak;mathematical study has examined cognitive performance during exercise
computations) [6]. Attempts to reconcile these conflicting in the heat as a function of age or following intermittent
2 BioMedResearchInternational
exerciseataconstantrateofthermaldrive,whichmatchesthe atestrequiringattentionandspeededinformationprocess-
workloadrequiredinmanyoccupationalsettings[8],where ing, were compared for young and older males following
∘
attentionandvigilancearecrucialforworkersafety. intermittent exercise in humid heat (35 C, 60% relative
Age-relateddecrementsinheatlossresponsesofsweating humidity[RH])underlowandhighairvelocityconditions.
and skin blood flow are known to compromise the ther- Thelowvelocitymaybeconsideredsimilartothattypically
moregulatory efficacy of older adults [9–11]. Consequently, employed in industrial settings, such as mining for general
concerns have been raised regarding the safety of older occupational hygiene related exposure control, whereas the
workersinoccupationswhichrequirephysicallydemanding higher air velocity (i.e., 3.0m⋅s−1) would be supplied to
tasks to be performed in the heat and/or while wearing mitigate heat stress in workers. To be consistent with the
protectiveclothingandtheneedforattention/concentration required absolute work rate in many occupational settings
inoperatingequipment(e.g.,deepundergroundandsurface [8], including deep underground mining, and a moderate-
mining,hydroelectricutilities,steelandchemicalplants,and to-heavy work rate as defined by the American Conference
others).Age-relateddecrementsinheatlossresponsesarenot ofGovernmentalIndustrialHygienists(ACGIH)[14],afixed
alwaysreflectedinmeasurementsoflocalheatlossresponses rateofheatproductionof400Wwasutilizedduringexercise
(e.g., sweat rate) and core temperature [11–13]. Given that tomaintainanequalheatloadandthereforeasimilarlevel
health and safety heat stress guidelines are based on core of thermal strain between groups. It was hypothesized that
temperature [14], it must be recognized that increases in increasedairvelocitywouldbelesseffectiveinreducingboth
thermal strain and thus potentially age-related differences thermal and cardiovascular strain, as well as any cognitive
in cognitive performance [15] may still be present in older decrements, in the older males as compared with young
adults.However,theextenttowhichage-relateddifferences males. It was also hypothesized that psychological sweating
in thermoregulation impact cognitive performance (e.g., inbothyoungandoldermaleswouldbepresentasaresult
informationprocessingandattention)iscurrentlyunknown, of increased attention and working memory demands but
particularly under conditions that restrict evaporative heat mightnotbeasevidentduringthelowairvelocitycondition
loss (i.e., humid heat and insulative protective clothing) compared to high air velocity condition due to increased
whichcanresultinincreasesinthermalstrain.Furthermore, skin wettedness as a result of a reduced capacity for the
inattemptstomitigatethermalstraininworkers,ventilation evaporationofsweat.
systems delivering large, and in some instances thermally
conditioned, air volumes have been utilized in deep under-
2.MaterialsandMethods
ground mining [16]. Such ventilation systems are required
to limit the increase in environmental temperature due to
2.1. Participants. Upon receiving approval from the Uni-
thevariousenergytransformationsandheatsourceswithina
versity of Ottawa Health Sciences and Science Research
minewhilealsoprovidingaflowtopromoteworkercooling.
Ethics Board, 9 young and 9 older healthy, active, nonheat
Thesupplyofsuitableventilationhasbeenshowneffectivein acclimated, nonsmoking males, matched for height, mass,
reducingthermalstrain(i.e.,coretemperature)inlabstudies andbodysurfacearea,wererecruitedforthestudy.Noneof
during exercise in heat in active young adults (i.e., 25–30 theparticipantshadahistoryofrespiratory,metabolic,car-
years)whilewearingminimalclothing[17–19].Moreover,ina diovascular,and/orhypertensiondisease,orskinconditions,
recentreport,increasedairvelocitywasshowntobeeffective andnonewereonanymedicationrelatedtotheseconditions.
during intermittent exercise in humid heat in young (i.e., All participants were moderately educated (at minimum)
∼25 years) and older (i.e., ∼60 years) males while wearing individualsfromthegeneralpopulationanduniversitycom-
work coveralls [13]. It remains unknown, however, whether munities with a wide range of occupations (e.g., students,
ventilation-mediated reductions in thermal strain impact construction, government, and general labour employees).
cognitiveperformanceinyoungandolderadults. Some participants from each group had moderate levels of
The primary purpose of this study was to examine the scientificbackgroundduetopriorresearchparticipation.All
influence of aging and increased air velocity on attention participantswereinformedoftheexperimentalprocedures,
andspeededinformationprocessing,followingintermittent associatedrisks,anddiscomfortspriortoprovidingwritten
exercise in humid heat under low (0.5m⋅s−1) and high consent.ParticipantcharacteristicsareshowninTable1.
(3.0m⋅s−1) air velocity work conditions in young (24.1 ±
0.5 years) and older (59.4 ± 1.2 years) males. Given that 2.2. Experimental Design. All participants completed one
cognitivestressand/orincreasedmentalworkloadhavebeen preliminaryscreeningsessionandtwoexperimentalsessions.
shown to increase sweating (termed psychological sweat- During the preliminary session, participants underwent a
ing),identifyingtheeffectsoftaskswhichrequiresustained progressive incremental test on a semirecumbent bike (one
attention and working memory on thermoregulatory and minutestageswith20Wincrementalincreases)todetermine
cardiovascularresponseswouldbeapplicabletooccupations maximaloxygenuptake(VO2peak)(AMETEKmodelsS-3A/1
whichrequireconcentrationandattentionunderpotentially andCD3A,resp.,AppliedElectrochemistry,AEITechnolo-
stressful conditions [20–22]. Thus, the secondary purpose gies,Pittsburg,PA,USA).Participantscycleduntiltheycould
of the study was to examine the influence of increased no longer maintain the predetermined cadence or stopped
attentional requirements and increased working memory due to volitional fatigue. During the VO2peak exercise test,
loadsonthermalandcardiovascularresponses.Accordingly, continuouselectrocardiogrammonitoringwasperformedin
thermal and cardiovascular responses, and performance on theolderparticipants(age>50years)(PulseBiomedicalInc.,
BioMedResearchInternational 3
Table1:Participantcharacteristics.
Age Height Mass BSA Bodyfat VO
2peak
(yr) (cm) (kg) (m2) (%) (mLO ⋅kg−1⋅min−1)
2
Young 24.1(0.5)a 174.6(3.2) 79.4(2.6) 1.95(0.05) 15.5(2.7)a 49.2(2.6)a
Older 59.4(1.2) 174.2(1.2) 81.5(4.1) 1.96(0.05) 25.6(2.6) 40.4(2.6)
Note:valuesaremean(SE).Bodysurfacearea(BSA);maximalaerobicpower(VO ).
2peak
aSignificantlydifferentthanoldermales.
Norristown,PA,USA).Bloodpressurewasmeasuredatevery from 30-second average values for oxygen uptake (VO2),
2nd stage or every 2min. Percent body fat was calculated accordingtothefollowingequation.
using the Siri equation [23], following the measurement of 𝑀(Watts)
bodydensitybyhydrostaticweighing.
The two experimental sessions followed a minimum of V̇O2∗[(RER−0.7/0.3∗𝑒𝑐)+(1−RER/0.3∗𝑒𝑓)]
2weeksafterthepreliminarysessionandwereseparatedby = ,
60
a minimum of 72 hours but performed at the same time
(1)
of day. Prior to arriving at the laboratory, participants were
instructedtoeatanormalbreakfastanddrinkwateradlibi- whereRERistherespiratoryexchangeratio(CO2produced/
tum,whilerefrainingfromcaffeineandexposuretothermal O2 uptake), 𝑒𝑐 is the caloric equivalent of a liter of oxygen
stimulifor12and24hourspriortoeachsession,respectively. when carbohydrates are oxidized (21.116kJ), and 𝑒𝑓 is the
Participants were also asked to refrain from alcohol and caloric equivalent of a liter of oxygen when fat is oxidized
exercise for 24 hours prior to each session. Upon arrival at (19.606kJ)[24].Stablemetabolicheatproductionvalueswere
thelaboratory,participantsprovidedaurinesample,inserted typically attained within the first 5min of the first exercise
bout, following which minimal adjustments were made to
therectaltemperatureprobe,satfora20-minutethermoneu-
maintain400W.
tralrestingbaseline,andwereinstrumentedwithaheartrate
Absolute oxygen uptake was not different between the
monitorandskintemperaturesensors.Participantsdonned
u∼n0d.1e9rwcleoa)r,(a𝐼ctl-=sh∼ir0t.0(5𝐼ccll=oi∼ns0u.1la0ticolon)),,lwonorgkuncodveerrwaellasr((𝐼𝐼ccll== oyolduenrg(1(3163538.0.254±±171.657.39anadnd1341345.27.111±±171.453.5m8mL⋅Lm⋅mini−n1−)1m) aanleds
∼0.61clo), socks (𝐼cl = ∼0.04clo), running shoes (𝐼cl = norbetweenairvelocityconditions.
∼0.04clo), work gloves, and a hard hat. Participants sub-
2.3.2.CoreTemperature. Rectaltemperature(𝑇 )wasmeas-
sequently entered the thermal chamber (Can-Trol Environ- re
ured continuously using a pediatric thermocouple probe
mentalSystemsLimited,Markham,ON,Canada)regulated
∘ (Mon-a-thermNasopharyngealTemperatureProbe,Mallinc-
at 35 C and 60% RH with an air velocity of 0.5 (low, first
krodtMedical,St.Louis,MO,USA),inserted12cmpastthe
experimental session) or 3.0 (high, second experimental
analsphincter.TemperaturedatawerecollectedusingaHP
session) m⋅s−1 where they rested for 30min while baseline
Agilentdataacquisitionmodule(Model3497A)atasampling
measurements were obtained. They then performed four
rateof15secandsimultaneouslydisplayedandrecordedon
15-minute bouts of cycling at a fixed rate of metabolic a personal computer with LabVIEW software (Version 7.0,
heat production of 400W, a moderate-to-heavy intensity NationalInstrumentsCorporation).
as defined by the ACGIH [14], separated by 15-minute rest
periods with a final resting recovery of 30min in duration. 2.3.3.LocalSweatRate. Localsweatrate(LSR)wasmeasured
2
This rate of heat production is comparable to the absolute usinga3.8cm ventilatedcapsuleaffixedtotheskinonthe
workraterequiredinoccupationalsettings(e.g.,mining)that forearm (LSRFA) and upper back (LSRUB) with an adhesive
areoftenperformedinhotenvironments[8,14]. ringandtopicalskinglue(CollodionHV,MavidonMedical,
LakeWork,FL,USA).Anhydrouscompressedairwaspassed
throughthecapsulesatarateof1L⋅min−1.Watercontentof
2.3.PhysiologicalandCognitiveMeasurements theeffluentairwasmeasuredusinghighprecisiondewpoint
mirrors(Model473,RHsystems,Albuquerque,NM,USA).
2.3.1.MetabolicHeatProduction. Toestablishafixedrateof
Localsweatratewasdeterminedbycalculatingthedifference
metabolicheatproductionof400W,theergometerresistance inwatercontentbetweentheeffluentandinfluentairforeach
was adjusted based on the concurrent measurements of capsule,multipliedbytheflowrate,andnormalizedforthe
expired oxygen and carbon dioxide concentrations (AME- skinsurfaceareaunderthecapsule.
TEKmodelsS-3A/1andCD3A,resp.,AppliedElectrochem-
istry,AEITechnologies,Pittsburg,PA,USA).Metabolicheat 2.3.4. Heart Rate. Heart rate was measured continuously
production was taken as the difference between metabolic using a Polar coded transmitter and recorded with a Polar
energy expenditure and the resistance, in Watts, on the Advantage interface and Polar Precision Performance soft-
ergometer.Metabolicenergyexpenditure(𝑀)wascalculated ware(PolarElectroOy,Finland).