Bioceramic fabrics improve quiet standing posture and handstand stability in expert gymnasts

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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 a

InstitutdeRechercheBiome´dicaledesArme´es,91223Bre´tignysurOrge,France b

UnivGrenobleAlpes,LPNC,F-38000Grenoble,France c_CNRS,_LPNC,_F-38000_Grenoble,_France

d_University_of_Fribourg,_Department_of_Medicine,_Fribourg,_Switzerland e_CNRS,_TIMC-IMAG,_F-38000_Grenoble,_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:[email protected](M.Guerraz).

Published in *DLW 3RVWXUH±

which should be cited to refer to this work.

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[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.

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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_),₍₃_and₄₎_{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₎_than_when_they_were_wearing_the_placebo_suit

(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. ₃_A). _The _same

Fig.2.Effectofthetwotypesofsuitonthelengthoftheswaypath(A–leftpanel)andtheareaofthe95%conﬁdenceellipse(B–rightpanel)withstandingsubjects.InbothA andB,errorbarsrepresentthe95%conﬁdenceinterval.

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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 _wearing_the_placebo

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.

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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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