Bioceramic
fabrics
improve
quiet
standing
posture
and
handstand
stability
in
expert
gymnasts
C.
Cian
a,b,c,
V.
Gianocca
d,
P.A.
Barraud
a,e,
M.
Guerraz
c,f,*
,
J.P.
Bresciani
c,d aInstitutdeRechercheBiome´dicaledesArme´es,91223Bre´tignysurOrge,France b
UnivGrenobleAlpes,LPNC,F-38000Grenoble,France cCNRS,LPNC,F-38000Grenoble,France
dUniversityofFribourg,DepartmentofMedicine,Fribourg,Switzerland eCNRS,TIMC-IMAG,F-38000Grenoble,France
f
UnivSavoieMontBlanc,LPNC,F-73000Chambe´ry,France
1. Introduction
Bioceramic materials, materials that emit high-performance
far-infrared (FIR) rays, have recently been the object of high
interest mainly for therapeutic purposes including
health-promoting practices [1]. Bioceramic garments may also be
manufacturedforperformanceenhancingapparelinbothleisure
activities and competitive sports area [2]. For Yoo et al. [3],
ceramicsincreasethermalinsulation byreflectingFIRraysfrom
thebodybacktothebodysurface.Theprinciplesourceofenergy
neededtopowertheFIRemissionfromthegarmentscomesfrom
thehumanbody.Energyfromthehumanbodyistransferredto
theseceramicparticleswhichareactingas‘‘absorbers’’,maintain
theirtemperatureatsufficientlyhighlevelsandthenemitFIRback
tothebody[2].ThebodycanexperienceenergyofFIRasaradiant
heatwhichcanpenetrateupto4cmbeneaththeskin.Elevationof
skintemperatureobservedsuggeststhatthismightresultofthe
accelerationofpercutaneousbloodcirculation[3].Enhancementof
skinmicrocirculationhasbeenshownusingFIRinananimalmodel
[4].Inlinewiththis,anincreaseinforearmbloodflowhasbeen
observedinrestingsubjectswhoseleftarmswereinfabricribbon
whichwaslinedwithceramicdisks[5].Gloveshavebeenmadeout
of FIR emitting fabrics and there have been reports that these
glovescanbeusedtotreatRaynaud’ssyndrome[6],notablyvia
improved vasodilatation and circulation. Significant
improve-mentswerealsodocumentedinbothsubjectivemeasuresofpain
anddiscomfortandinobjectivemeasuresoftemperatureandgrip
[6].
Theusefulnessofbioceramicmaterialsaddedintofabricshas
alsobeenshown duringphysicalexercise.Forinstance,ceramic
coatedclothingincreasedbloodflowduringa30minexerciseona
bicycleergometerataworkrateof75Winacoolenvironment
Bioceramicfabrics have been claimedto improve blood circulation,thermoregulation and muscle relaxation,therebyalsoimprovingmuscularactivity.Herewetestedwhetherbioceramicfabricshavean effectonposturalcontroland contributeto improveposturalstability.InExperiment1,we tested whetherbioceramic fabrics contributeto reducebody-sway when maintainingstandard standing posture.InExperiment2,wemeasuredtheeffectofbioceramicfabricsonbody-swaywhenmaintaining amoreinstableposture,namelyahandstandhold.Forbothexperiments,posturaloscillationswere measuredusingaforceplatformwithfourstraingaugesthatrecordedthedisplacementsofthecenterof pressure(CoP)inthehorizontalplane.Inhalfofthetrials,theparticipantsworeafull-bodysecondskin suitcontainingabioceramiclayer.Intheotherhalfofthetrials,theyworea‘placebo’secondskinsuit thathad the same cut,appearance and elasticity asthe bioceramic suit but didnot contain the bioceramiclayer.Inbothexperiments,thesurfaceofdisplacementoftheCoPwassignificantlysmaller whenparticipantswerewearingthebioceramicsuitthanwhentheywerewearingtheplacebosuit.The resultssuggestthatbioceramicfabricsdohaveaneffectonposturalcontroland improvepostural stability.
* Correspondingauthorat:LaboratoryofPsychologyandNeuroCognition,UMR 5105CNRS–UniversitySavoie MontBlanc,BP1104,73011ChamberyCedex, France.Tel.:+33479759186;fax:+330479758599.
E-mailaddress:Michel.guerraz@univ-savoie.fr(M.Guerraz).
Published in *DLW 3RVWXUH±
which should be cited to refer to this work.
[7].Moreover,thereweretendenciestowarddecreasedtiredness
andreducedskintemperaturein subjectswearingabioceramic
shirt while running 30min at a steady velocity of 6km/h;
[1].Leungetal.[8]usedelectro-stimulationofamphibianskeletal
muscleandfoundthatFIRemittingceramicsdelayedtheonsetof
fatigueinducedbymusclecontraction.Theyalsosuggestedthat
thepresenceofbioceramicscouldnormalizeacidification
follow-ingmusclecontractions.Eventhoughtheexactmechanismsofthe
hyperthermiceffectsandbiologicalactivitiesofFIRirradiationare
still poorly understood, converging evidence suggests that
bioceramic materials contribute to increase fatigue resistance,
decreaseenergy expenditure even during steady state [1] and,
improvedexterity[6].
Physicalbutalsonormaleverydayactivitiesdependtoalarge
extentontheabilitytocontrolourbalance.Posturalequilibrium
involves actively maintaining the chosen body configuration
against gravity, and internal or external disturbances [9]. It
thereforeconstitutesanimportantattributeofthe
musculoskele-tal-proprioceptive apparatus with skeletal muscles continually
makingfineadjustmentsthat holdthebody inquasi-stationary
positions.Anywaytoimprovephysicalperformance,dexterityand
muscle fatigue, might therefore significantly affect postural
performance.Therefore,bioceramicgarmentsmightwell
contrib-ute to improve postural control, which to the best of our
knowledgehas never been investigated. In thepresent
experi-ments, we tested whether bioceramic fabrics affect postural
stabilityduringunperturbedstandinginnon-athleteparticipants
andformaintainingahandstandholdinexpertgymnasts.
2. Materialsandmethods
2.1. Participants
TwelveparticipantsparticipatedinExperiment1(aged20–35,
mean=28.5,6males).Fourteenconfirmedgymnasts(nationally
rankedinSwitzerland,havingmorethan10yearsofexperience
in gymnastics competition at the regional level or higher)
participatedinExperiment2(aged15–28,mean=21.5,9males).
Theseparticipants wereselected fortheir ability tomaintain/
sustain a handstand hold for at least 5s.Participants had no
historyofbalanceorneuromusculardisorder.Theywerenaı¨veto
theaimofthestudyandgaveinformed-writtenconsentpriorto
thestudy.Theresearchwasperformedinaccordancewiththe
ethicalstandardsspecifiedbythe1964DeclarationofHelsinki
andapproved by theethicsreview boardof the Universityof
Fribourg.
2.2. Apparatus
Bothexperimentstookplaceinawell-litroom.Aforceplatform
equippedwithfourstraingaugeslinkedtoacomputerwasusedto
recordthedisplacementsofthecenteroffeet(Experiment1)or
hand(Experiment2)pressure(CoP)inthehorizontalplane(i.e.,
alongtheX-andY-axis).Theforce-platformwasdevelopedinthe
BiomedicalResearchInstituteofFrenchArmedForces(IRBA).Itis
madeoftwosteelplates(50cm50cm3cm)andhasatotal
height of 18cm. The upper plate lies on four strain gauges
(AG50C3SH10ef SCAIME) close tothe verticesof theplate and
distantfromeachotherby40cm.Themeanresolutionfora70kg
subjectstandinginthecentreoftheplatformisinferiorto0.1mm.
The sampling frequency of the platform is 100Hz, and high
frequencieswereattenuatedusingasecond-orderlow-passfilter
with a 10Hz cut-off frequency. The antero-posterior (AP) and
medio-lateral(ML)axesarereferencedtotheforceplatform.
Twotypesofsuit wereworn bytheparticipantsduring the
experiment:BioceramicandPlacebosuits.Bothtypesofsuitwere
madeofpolyester(85%)andspandex(15%)inadditiontowhich
bioceramicsuitsalsointegratedabioceramicinduction/layer(7g
ofbioceramic/m2ofcloth,i.e.,5%oftotalfabrics’weight).Allsuits
consistedofsecond-skin,two-piece(topandbottom)blacksuits
coveringthewholebodyfromnecktowristsandankles.Thesuits
cameinfourdifferentsizes(S,M,LandXL)andthesizewornby
anygivenparticipantwasalwaysthesameforthebioceramicand
placebosuits.Foranygivensize,bioceramicandplacebosuitswere
identical in size, appearance and elasticity (220%). The only
differencebetweenbioceramicandplacebosuitswasagarment
labelindicatingAorB.
2.3. Task
Experiment1:Participantswereinstructedtostandquieton
theforceplatformwitharmsrelaxedonthesideofthebodywhile
fixinga plumb linelocated90cmin front ofthemfor the60s
durationofthetrial.Theystoodbarefootontheplatformwiththeir
feetabductedat308andheelsseparatedby2cm.
Experiment2:Atthebeginningofeachtrial,thegymnastsgot
upintoahandstandontheforceplatform.Anexperimenterhelped
themestablishandstabilizeaproperhandstandposition.Oncethe
gymnastsfelttheywerecomfortableandstableinthisposition,
theexperimenterreleasedtheirlegs.Theirtaskwastomaintain
thepositionandtrytoswayaslittleaspossibleforthe5sduration
ofthetrial.Attheendofthetrial,theexperimentertookholdof
their legsand helped bringing them backon thefloor.For the
handstand,eachgymnastwasfreetousethehandwidththatwas
themostcomfortableforhim/her.Buttheywerethenrequiredto
usethesamehandwidthandpositionthroughouttheexperiment.
Fig.1showsaparticipantperformingthetask(i.e.,maintaininga
handstand)withoneoftheexperimentalsuits.
2.4. Design
Experiment1:Participantsperformedfourtrialspersuittype,
foratotalof8trials.Eachtriallasted60switha1minrestbreak
Fig.1.Aparticipantwearingthebioceramicsuitwhileperformingthestanding (Experiment1,leftimage)andthehandstand(Experiment2,rightimage)postural tasks.Differentparticipantsparticipatedinthetwoexperiments.
betweentwosuccessivetrials.Participantsalsogota10minbreak
tochangesuitafterfourtrialswereperformedwiththefirstsuit
type.Halfoftheparticipantsstartedwiththebioceramicsuit,and
theotherhalfwiththeplacebosuit.
Experiment2:Gymnastsperformedfivetrialspersuittype,
for a totalof ten trials.Each trial lasted5switha 1minrest
break between two successive trials. After five trials were
performedwithonesuittype,thegymnastshada10minbreak
during which they changed suit before completing a second
seriesoffivetrialswiththesecondsuittypes(stillwith1min
restbetweeneachtrial).Toavoidanyfatigue-relatedbiasinthe
results, half of the gymnasts (seven) started the experiment
wearing the bioceramic suit, and the other half wearing the
placebosuit.
A double-blind procedure was used for both experiments.
Neithertheparticipantsnortheexperimentersdidknowwhichof
the A and B suits corresponded to bioceramic and placebo,
respectively.Theexperimentslastedabout45mineachincluding
instructions.
2.5. Dataanalysis
For each trial,six parameters werecalculated from theCoP
coordinates(XandY):(1)lengthofswaypath(mm),i.e.,thetotal
distancetravelledbytheCoPoverthetrialperiod,2)areaofthe
95%confidenceellipse(mm2),(3and4)antero-posterior(AP)and
medio-lateral (ML) range of motion of the CoP (mm), i.e., the
differencebetweenthetwoextremepositionvaluesoftheCoPin
therespectivedirections,and(5and6)velocity(mm/s)forAPand
MLmotionoftheCoP.MovementsoftheCoPwerecalculatedwith
Matlab 7.8 (MathWorks) following to therecommendations of
Schubertetal.[10].
Foreachparticipant,suitcondition,anddependentvariable,
themean valueandthe standard deviationof themean were
computed.Foreachdependentvariable,theresultingvaluesin
the two suit conditions were compared (bioceramic suit vs
placebo suit) using paired t-tests when all assumptions of
parametricdataweremet,andusingWilcoxonsigned-ranktests
otherwise.Thesetestsallowedustoassesswhetherthetwotypes
ofsuitaffecteddifferentlytheaveragebody-swaybutalso
body-swayvariability.
3. Results
3.1. Experiment1
Length: The swaypath of theCoP wassignificantly shorter
whenparticipantswerewearingthebioceramicsuit(meanlength
ofthepath=602mm)thanwhentheywerewearingtheplacebo
suit(meanlengthofthepath=632mm,t(11)= 4.379,p=.0011,
r= .80, see Fig. 2A). Individual sway path variability
(intra-subject)wasnotaffectedbythesuittype.
Areaofthe95%confidenceellipse:AscanbeseeninFig.2B,the
surfaceofdisplacementoftheCoPwassignificantlysmallerwhen
participants were wearing the bioceramic suit (mean
area=192mm2)thanwhentheywerewearingtheplacebosuit
(meanarea=231mm2),t(11)= 2.935,p=.021,r=.66.Individual
surfacevariability(intra-subject)wasunaffectedbythesuittype.
Range:Neithertheantero-posteriornorthelateralrangedid
significantly differ between the two suit conditions. Individual
rangevariabilitywasnotalteredeitherbythesuittype.
Velocity:Themeanvelocityofantero-posteriordisplacementsof
theCoPwassignificantlysmallerwiththebioceramic(mean=7.40,
SD=1.65) than with the placebo suit (mean=7.84, SD=1.68),
t(11)= 4.62,p=.0007,r=.81.Therewasalsoadifferenceinlateral
sway velocitybetween bioceramic (mean=5.29, SD=1.12) and
placebo suits (mean=5.48, SD=1.29), but it failed to reach
significance (t(11)= 1.84, p=.09, r=.49). Individual velocity
variabilityremainedunaffectedbythesuittype.
3.2. Experiment2
Length: The sway path of the CoP was shorter with the
bioceramic suit (mean=535.6mm)than withthe placebo suit
(mean=569.5mm),indicatingthatparticipantsswayedlesswhen
wearing the bioceramic suit. This difference failed to reach
significance,t(13)= 1.816,p=.0924,eventhoughtheeffectsize
wasfairlysubstantial,r=.45.Individualswaypathvariabilitydid
notdiffersignificantlybetweenthetwosuitconditions.
Areaofthe95%confidenceellipse:Thesurfaceofdisplacement
oftheCoPwassignificantlysmallerwiththebioceramicsuit(mean
area=1941mm2) than with the placebo suit (mean area=
2667mm2), Z=5, p=.0012, r= .61 (see Fig. 3A). The same
Fig.2.Effectofthetwotypesofsuitonthelengthoftheswaypath(A–leftpanel)andtheareaofthe95%confidenceellipse(B–rightpanel)withstandingsubjects.InbothA andB,errorbarsrepresentthe95%confidenceinterval.
patternwasobservedfor12outofthe14participants.Asshownin
Fig.3B,thetypeofsuitalsoaffectedsignificantlytheindividual
(i.e., intra-subject) variability of the surface of displacements,
t(13)= 2.27,p=.0407,r=.53.Specifically,variabilitywassmaller
when participants were wearing the bioceramic suit (mean
standard deviation=632mm2)than when wearingtheplacebo
suit(meanstandarddeviation=1152mm2).
Range:AsshowninFig.4A,themeanrangeofantero-posterior
displacements of the CoP was significantly smaller with the
bioceramic (m=51.91mm) than with the placebo suit
(m=56.17mm),t(13)= 2.278,p=.0403,r=.53.Themeanrange
of displacement along the left-right axis (Fig. 4B) was also
significantly smaller with the bioceramic (m=34.62mm) than
withtheplacebo suit(m=44.83mm),t(13)= 2.432,p=.0302,
r=.56.Ontheotherhand,thesuittypedidnotaffectindividual
rangevariability.
Velocity:Themeanvelocityofantero-posteriordisplacementsof
the CoP was not significantly different with the bioceramic
(mean=81.73)thanwiththeplacebosuit(mean=83.67),t(13)=
0.68,p=.506,r=.19.Themeanvelocityoflateraldisplacements
wassignificantlysmallerwiththebioceramic(m=50.99)thanwith
the placebo suit (m=57.60), t(13)= 2.78, p=.0134, r=.61.
Individualvelocityvariabilitywasnotaffectedbythesuittype.
4. Discussion
UsingaforceplatformtomeasurethedisplacementsoftheCoP,
wetestedtheimpactofbioceramicfabricsonposturalcontrolin(i)
a standard standing postural task (Experiment 1) and (ii) a
handstandstabilizationtaskwithexpertgymnasts(Experiment2).
Postural control was quantified by measuring the length,
surface,rangeandvelocityofdisplacementoftheCoP.Thefirst
threevariables(i.e.,length,surfaceandrange)constitute‘direct’
indicatorsofposturalcontrolefficiency,whereasCoP velocityis
supposed to be an indicator of muscular force variations, and
therefore an ‘indirect’ indicator of postural control efficiency
[11–13]. In Experiments 1 and 2, the surface and velocity of
displacement of the CoP were significantly smaller when
participants were wearinga bioceramic suit as compared toa
placebosuitofsamecut,size,appearanceandelasticity.Inthefirst
experiment, withstandingparticipants, thelengthof thesway
path wasalso shorter with the bioceramic suit than with the
Fig.3.Effectofthetwotypesofsuitontheareaofthe95%confidenceellipse(A–Leftpanel)andtheintra-subjectvariabilityofsurfaceofdisplacement(B–Rightpanel)with subjectsholdingahandstand.InB,errorbarsrepresentthe95%confidenceinterval.
Fig.4.EffectofthetwotypesofsuitonthemeanrangeofdisplacementoftheCoPalongtheantero-posterioraxis(A–Leftpanel)andtheleft-rightaxis(B–Rightpanel)with subjectsholdingahandstand.InbothAandB,errorbarsrepresentthe95%confidenceinterval.
placebosuit.Theseresultsshowthatthebioceramicsuithelped
participantsimprovingtheirposturalstability,whetherstanding
ontheirfeetormaintainingahandstandhold(forthegymnasts).
Whenparticipantsweremaintaininguprightstance,wearing
bioceramicgarmentsresultedina5%reductionofboththelength
oftheswaypathandthevelocityofthedisplacementsoftheCoPin
theantero-posteriordirection.However,nosignificantdifference
wasobservedfortheantero-posteriorrangewhichrepresentsthe
amplitudeof bodymotion along theantero-posterior axis.This
suggests that when wearing the bioceramic suit, participants
requiredless frequent correctionsto achievea similarpostural
stability.
Ingymnastics,thehandstandisestimatedtobecorrectifthe
bodysegmentsarealignedandthebodydoesnotmove,i.e.,moves
aslittleaspossible.Inthatrespect,CoPsurface,whichestimates
theamplitudeofbodymotion,appearstobethemainparameterto
discriminate gymnasts’ performance. In our experiment, CoP
surface was reduced by 27% when gymnasts wore bioceramic
suits.Inaddition,individualvariabilityofCoPsurfacewasalmost
halved with respect to placebo. This indicates that bioceramic
garments helped the gymnasts improving their stability and
producing a ‘stable’ performance. Handstand stability was
improved by bioceramic along both the lateral and
antero-posterior axes, as evidenced by the observed reduced range.
Interestingly,improved stabilitywasobservedfor12out ofthe
14 gymnasts that participated in the experiment. The two
gymnastsforwhomtheeffectwasnotpresentwerethegymnasts
presentingthesmallestCoPsurface(irrespectiveofthesuit),i.e.,
themoststablegymnasts.Thissuggeststhatbioceramicfabricsare
mostefficientwhenstabilityisimpaired,whichwouldalsoexplain
themuchlargereffectsobservedonthehandstandholdthanon
thestandarduprightposture.
Forposturalregulationin thehandstand asinerectposture,
sensoryperceptionisessential.Inlinewiththis,visual,
somato-sensory,andvestibularafferentsareintegratedforposturalcontrol
[9,14–21], and stimulation of these sensory systems evokes
changesinbody sway.In ourtwoexperiments,thestimulation
of thesedifferentsensory channels wassimilaracross thetwo
experimental conditions, namely with bioceramic and placebo
suit.Therefore,theobservedimprovementinposturalcontrolis
veryunlikelytoresultfromadifferenceinsensorystimulationor
sensory weighting. Finally, upright stance and handstand are
characterized by a body configuration that is unstable from a
biomechanicalperspectiveandrequirescontinuouscontrolbythe
neuromuscularsystemtomaintainbalance.Itcanbesuggested
thatbioceramicmaterialscouldinfluencetheprocessbywhichthe
bodyvarymusclecontractioninimmediateresponsetoincoming
informationregardingexternalforces.
Eventhoughphysiologicaleffects ofbioceramicgarmentson
posture remain unknown, our results show that it improves
postural control in young non-athlete participants and expert
gymnasts.Decline ofbalance functionis considered one of the
factorslikelytoberesponsibleforfallsina largepercentageof
olderadults[22–24].Indeed,asweage,balancefunctionstartsto
declineandcontrolofstancecanbecomedifficultformanyolder
adults.Itwouldthereforebeusefultostudyifbioceramicgarments
couldalsoimprovebalancestabilityinolderadultsandtherefore
reducethelikelihoodoffalls.
Authorcontribution
CC,MGandJPBconceivedanddesignedthestudy,andwrote
the article. CC, VG and JPB collected the data. All authors
contributedtodataanalysisandinterpretation.Allauthorsrevised
thedraft version of the article, and all approve the submitted
version.
Competinginterests
Noneoftheauthorshaveanyconflictsofinterests.
Acknowledgement
WethankHTConcept(http://www.htconcept.com/index.php/
presentation.html)forprovidingbioceramicandplacebosuits. References
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