Propulsion Calculated by Force and Displacement of Center of Mass in Treadmill Cross-Country Skiing
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P opulsion Calcula ed by Fo ce and Displacemen o Cen e o Mass in T eadmill C oss-
Coun y Skiing
© 2022 he Au ho s
Published e sion
Zhao, Shuang; Oh onen, Olli; Ruo salainen, Keijo; Ke unen, Lau i; Lindinge ,
S e an; Göp e , Ca oline; Linnamo, Vesa
Zhao, S., Oh onen, O., Ruo salainen, K., Ke unen, L., Lindinge , S., Göp e , C., & Linnamo, V.
(2022). P opulsion Calcula ed by Fo ce and Displacemen o Cen e o Mass in T eadmill C oss-
Coun y Skiing. Senso s, 22(7), A icle 2777. h ps://doi.o g/10.3390/s22072777
2022
Senso s2022,22,2777.h ps://doi.o g/10.3390/s22072777www.mdpi.com/jou nal/senso s
A icle
P opulsionCalcula edbyFo ceandDisplacemen
o Cen e o MassinT eadmillC oss‐Coun ySkiing
ShuangZhao
1
,OlliOh onen
1
,KeijoRuo salainen
1
,Lau iKe unen
2
,S e anLindinge
3
,Ca olineGöp e
4
andVesaLinnamo
1,
*
1
Facul yo Spo andHeal hSciences,Uni e si yo Jy äskylä,40014Jy äskylä,Finland;
zhaoshuangzs@ho mail.com(S.Z.);olli.oh one[email p o ec ed](O.O.);keijo.s. uo salain[email p o ec ed](K.R.)
2
Facul yo In o ma ionTechnology,Uni e si yo Jy äskylä,40014Jy äskylä,Finland;
lau i.y.o.ke unen@jyu. i
3
Cen e o Heal handPe o mance(CHP),Depa men o FoodandNu i ionandSpo Science,
Uni e si yo Go henbu g,40530Gö ebo g,Sweden;s e an.lindinge @gu.se
4
Depa men o Spo ScienceandKinesiology,Uni e si yo Salzbu g,5400Salzbu g,Aus ia;
ca o.g[email p o ec ed]
*Co espondence: esa.linnamo@jyu. i
Abs ac :Thiss udye alua ed woapp oaches o es ima ing he o alp opulsi e o ceonaskie ’s
cen e o mass(COM)wi hdouble‐poling(DP)andV2‐ska ing(V2)skiing echniques.Wealso
assessed heaccu acyand hes abili yo eachapp oachbychanging hespeedand heinclineo
he eadmill.A o alo 10c oss‐coun yskie spa icipa edin hiss udy.Fo cemeasu emen
bindings,pole o cesenso s,andaneigh ‐came aViconsys emwe eused o da acollec ion.The
coe icien o mul ipleco ela ion(CMC)wascalcula ed oe alua e hesimila i ybe ween he o ce
cu es.Meanabsolu e o cedi e encesbe ween hees ima ed aluesand he e e ence aluewe e
compu ed oe alua e heaccu acyo eachapp oach.Inbo hDPandV2 echniques, he o ce– ime
cu eso he o wa dcomponen o he ansla ional o cewe esimila o he e e ence alue
(CMC:0.832–0.936).Thesimila i ybe ween he o ceand imecu eso he o wa dcomponen o
heg ound eac ion o ce(GRF)and he e e ence aluewas,howe e ,g ea e (CMC:0.879–0.955).
Bo happ oachescanes ima e he endo he o ce– imecu eo hep opulsi e o cep ope ly.An
app oachbycalcula ing he o wa dcomponen o GRFisamo eapp op ia eme hoddue oa
be e accu acy.
Keywo ds:p opulsi e o ce;V2‐ska ingskiing echnique;double‐polingskiing echnique
1.In oduc ion
Fo cesac ingonaskie ’scen e o mass(COM)ina o wa ddi ec iona ep opulsi e
o ces,whicha e hep ima ymechanicalde e minan so anc oss‐coun y(XC)skie ’s
pe o mance[1].Theposi iono skie ’sCOMcanbeob ainedbyusing hema ke ‐based
mo ioncap u esys emwi hasegmen alme hod[2].Thus, o cesac ingonaskie ’sCOM
canbeob ainedbymul iplyingCOMaccele a ionwi h he o almasso heskie ,and his
willindica ehowa hle eso e come esis i e o ces.Howe e , hecon ibu iono single
poleandleg h us scouldno be e ealed.The e o e,i isessen ial ocompu e o cesac ing
on heCOM om heg ound eac ion o ces(GRFs)gene a ed omskisandpoles,
sepa a ely.
Excep o es ima ing hep opulsi e o cewi h he o wa daccele a iono COMand
he o almass,o he app oachesha ebeende eloped.Oneapp oachis oes ima e he
p opulsi e o ceas he o wa d‐di ec edho izon alcomponen o he h ee‐dimensional
(3D)GRFs ombo hskisandpoles ha ac onaskie (F
ne
)[3].The olle skis[3‐5],skis
[6,7],andpoles[3,6,7]equippedwi h o cesenso sha ebeenused omeasu e he o ces
Ci a ion:Zhao,S.;Oh onen,O.;
Ruo salainen,K.;Ke unen,L.;
Lindinge ,S.;Göp e ,C.;
Linnamo,V.P opulsionCalcula ed
b
yFo ceandDisplacemen o Cen e
o MassinT eadmillC oss‐Coun y
Skiing.Senso s2022,22,2777.
h ps://doi.o g/10.3390/s22072777
AcademicEdi o :Ch is ianPeham
Recei ed:17Janua y2022
Accep ed:2Ap il2022
Published:5Ap il2022
Publishe ’sNo e:MDPIs ays
neu alwi h ega d oju isdic ional
claimsinpublishedmapsand
ins i u ionala ilia ions.
Copy igh :©2022by heau ho s.
LicenseeMDPI,Basel,Swi ze land.
Thisa icleisanopenaccessa icle
dis ibu edunde he e msand
condi ionso heC ea i eCommons
A ibu ion(CCBY)license
(h ps://c ea i ecommons.o g/license
s/by/4.0/).
Senso s2022,22,27772o 14
gene a ed omskisandpoles.Combinedwi h hepoleangle,skiangle,ski‐edgingangle,
and heinclineo he acko he eadmill, hep opulsi e o ce omskisandpolescanbe
speci ied[1,3,8].The e o e,ques ions ela ed o hep opulsi e o ce,including he
con ibu iono skisandpolesindi e en echniques[3,9,10],and hecompa isono
di e en echniques[11,12]ha ebeenadd essed.Ano he app oach,demons a edby
Göp e e al.[6],is oes ima e hep opulsi e o cewi h he o wa dcomponen o
ansla ional o ce(Fp o).The ansla ional o cewasmodeledas hecomponen o he3D
esul an GRFs ha ac sin hedi ec ion om hepoin o o ceapplica ion(PFA) oaskie ’s
COM[6],andcalcula edbyp ojec ing heGRFs o helinede inedby heCOMandPFA.
Thep opulsi e o cesob ainedwi h he women ionedapp oaches(Fne andFp o)
ha ebeencompa ed o hep opulsi e o cecalcula edwi hCOMaccele a ion oma
mo ionanalysissys em(F)in[6].Asusing hesegmen alme hodhasbeenshown obe
sui able o es ima ing heposi iono heCOMinspo s[2],Fwasconside edas he
e e ence alue.The esul sindica ed ha he o ce– imecu eso Fne andFp oallshowed
highsimila i ywhencompa ed o he o ce– imecu eso Fdu ing helegska ingpush‐
o sonsnow.Fne o e es ima edF,andFp owas ound obeamo eapp op ia eapp oach
oes ima eFdu inglegska ingpush‐o s[6].Howe e ,whe he Fne andFp ocouldbe
used oes ima eF,andwhichoneismo eaccu a eino he echniques,a es illunknow.
AsXCskiingisaspo whosecompe i ionand aininga eno mallype o medon
a ying ack opog aphyandspeed,whe he Fne andFp ocouldwo ks eadilywhen
es ima ingFa di e en e ainwi hdi e en speedsneed u he in es iga ion.
The e o e, he i s aimo hep esen s udywas oob ain he o ce– imecu eso
Fne andFp owi hdi e en skiing echniquesande alua ewhichcanes ima e he o ce–
imecu eso Fbe e .As heuseandimpo anceo doublepoling(DP)andV2ska ing
(V2)asmain echniquesinXCskiingha einc eased o hepas ewyea s[12‐14],DPand
V2ska ing echniqueswillbepe o medin hiss udy.Thesecondaimis oin es iga e
whichapp oachismo eaccu a ewhenes ima ingF.Ano he aimis oexplo e he
s abili yo heapp oaches ocalcula eFne andFp obychanging hespeedandinclineo
he eadmill.Wehypo hesized ha he o ce– imecu eso Fne andFp oallgi e
compa ableshapewi hFinbo h echniques[6].Wealsohypo hesized ha Fne would
gi eaconside ableo e es ima ion,andFp owouldbemo eaccu a e hanFne ,when
es ima ingFinbo hDPandV2 echniques[6].We u he hypo hesized ha he
app oaches ocalcula e heFne andFp owouldno bea ec edby hespeedandinclineo
he eadmillinbo h echniques.
2.Ma e ialsandMe hods
2.1.Pa icipan s
A o alo 10expe iencedmaleskie s(age:29.4±7.9yea s;heigh :181.4±5.7cm;
weigh :77.9±8.9kg)whowe e amilia wi h eadmill olle skiing olun ee ed o
pa icipa ein hiss udy.Theexpe imen alp o ocolandallme hodsusedin hiss udy
we eapp o edby heE hicsCommi eeo heUni e si yo Jy äskylä.Allpa icipan s
p o idedw i enin o medconsen be o e hemeasu emen andwe e ee owi hd aw
om heexpe imen sa anypoin .
2.2.P o ocol
Thean h opome icpa ame e sneeded o mo ionanalysis(e.g.,bila e allegleng h,
kneewid h,anklewid h,shoulde o se ,elbowwid h,andhand hickness)we e
measu ed i s ,andpassi e e lec i ema ke swe ea ached o hepa icipan sand
equipmen .Once hep epa a ionswe emade,pa icipan scomple eda10–15minwa m‐
up olle skiingon he eadmill.Nex ,calib a ionwaspe o medwi h heskie ina
s andingposi ionand he eadmilla a0°incline.Pa icipan s henpe o med heDP
echniquea i espeeds(13,15,17,19,and21km/h)ona2°incline.Thecom o ablepole
leng h o heDP echniquewas1.56±0.06m.A e he ialswi h a yingspeedsa a2°
Senso s2022,22,27773o 14
incline, heDP echniquewaspe o meda h eeinclines(3°,4°,and5°)wi haspeedo
10km/h.The ewasa1min es be weeneachspeedandincline.Whenpa icipan s
inishedpe o ming heDP echnique, hepoleleng hwasadjus ed oacom o able
leng h o heV2ska ing echnique(whichwas1.63±0.03min hiss udy).The
pa icipan swe egi enasho es pe iodwhileadjus ing hepoleleng h.The
pa icipan s henpe o med heV2 echniqueon he eadmill.Thep o ocol o speedand
inclinechangewas hesameasdu ing heDP es .
2.3.Da aCollec ion
Aneigh ‐ ideo‐came amo ioncap u esys em(Vicon,Ox o d,UK)andNEXUS2.8.1
so wa ewe eused ocollec and eco d he3D ajec o ieso e lec i ema ke sa a
sampling a eo 150Hz.Theglobalcoo dina esys em(GCS)wasde inedusing he igh ‐
hand ulewhen heinclineo he eadmillwas0°.TheX‐axiso heGCSwasde inedas
hedi ec ion omside osideac oss he eadmill.TheY‐axiso heGCSwas he
longi udinalaxiso he eadmill.TheZ‐axiso heGCSwaspe pendicula o heg ound,
poin ingupwa d.TheGCSwascalib a edacco ding oVicon’sspeci ica ions.A o alo
58passi e e lec i ema ke swe eusedin hiscu en s udy:43passi e e lec i ema ke s
we ea ached o hepa icipan s’bodies,and15ma ke swe ea ached o heequipmen ,
includingbo hskis(3each),bo hpoles(3each),and he eadmill(3).An h opome ic
measu emen sand heplacemen o ma ke son hepa icipan s’bodieswe econduc ed
acco ding o heXCmodel[6]usedinp e iouss udies.Measu emen swe epe o med
onamo o ized eadmillwi habel su aceo 2.7mwideand3.5mlong(Rodby
Inno a ionAB,Vänge,Sweden).Thesamepai o olle skiswe eused o bo h
echniques(Ma we,SKATING620XC,wheelno.0),wi ha esis ance ic ioncoe icien
o μ=0.025measu edbe o e hemeasu emen (AppendixA).
Twocus om‐madepole o cesenso s(VTTMIKES,TechnicalResea chCen eo
FinlandL d.,Kajaani,Finland,Figu e1a)we eused omeasu e heaxialGRF om he
poles.Twocus om‐made wo‐dimensional(2D) o cemeasu emen bindings
(Neu omuscula Resea chCen e,Uni e si yo Jy äskylä,Jy äskylä,Finland,Figu e1b)
[15]we emoun edon olle skis omeasu e heleg o cesgene a ed om olle skis.Bo h
poleandleg o ceswe ecollec edsynch onouslywi h heCoach echonlinemeasu emen
and eedbacksys em(Neu omuscula Resea chCen e,Uni e si yo Jy äskylä,
Jy äskylä,Finland)a asample a eo 400Hz.The o cemeasu emen bindingsmeasu ed
he e ical(F
skiz
)andmediola e al(F
skix
) o cesandwe ecalib a edbe o e he
measu emen [15].A igge signalwassen om heCoach ech[16] o hemo ioncap u e
sys em oma k hes a o he o cecap u e.Thenodes o hepole o cesenso sand
o cemeasu emen bindingswe eused osupplypowe and ansmi da a.
Figu e1.Equipmen usedin hiss udy:(a)Pole o cemeasu emen senso .(b)Fo cemeasu emen
binding.
Senso s2022,22,27774o 14
2.4.Da aReduc ion
Ma ke labelingandCOMcalcula ionswe epe o medusingNEXUS2.8.1so wa e.
The aw3D ajec o ieso all e lec i ema ke sand heaccele a iono COMwe elow‐
pass il e ed( ou h‐o de ,ze o‐lag,andBu e wo h il e )wi hacu o equencyo 11.3
Hz[17].TheXCmodel[6],whichcon ained hehead, ho ax,abdomenandpel is,uppe
a ms,hands, highs,shanks, ee ,skis,andpoles,wasused ocalcula e hewhole‐body
COM.Thema ke placemen on hesubjec andgeome icmodel o heXCmodelis
showninFigu e2.Thesegmen alan h opome icda awe e aken omDemps e ’ss udy
asdesc ibedinSelbiee al.[18].Fo ceda awe elow‐pass il e ed(eigh h‐o de ,ze o‐lag,
andBu e wo h il e )wi hacu o equencyo 15Hz[19].Da a il e ingandpa ame e
calcula ionswe epe o medusingMATLABR2018a(Ma hWo ks,Na ick,MA,USA).
Figu e2.Ma ke placemen on hesubjec andgeome icmodel o segmen sin heXCmodel.The
numbe s1–49 ep esen heplacemen o e lec i ema ke sonsubjec sandpoles.Thedisplacemen
o e lec i ema ke son olle skisisshowninFigu e3.Thenumbe s1–39a e hema ke susedin
heplug‐in‐gai (PIG)model.1–43a e hema ke susedin heXCmodel
[6]
ononesubjec .The
numbe s44–49a e hema ke son hepoles.①–⑪ ep esen hehead, ho ax,abdomenandpel is,
uppe a m, o ea m,hand, high,shank, oo ,pole,and olle ski, espec i ely.
Figu e3.Displacemen o ma ke s,PFAs,and hede ini iono FCS(ı
,ȷ,k
).Th eema ke s(Ski_1,
Ski_2,andSki_3)we ea ached o hesideo henode.Thenode o powe supplyandda a
ansmissionwasa ached o he on pa o he olle ski.Thesu acede inedby hema ke swas
pa allel o he olle skisu ace.ı
wasde inedbySki_3andSki_2.Ano he uni ec o (
)loca edon
hesu aceo he olle skiwasde inedbySki_1andSki_2.Thesu aceno m,whichwas hek
o
FCS,was hec ossp oduc o ı
and
.Thelas uni ec o ȷwascompu edbyusing he igh ‐hand
ulewi hk
andı
.ThePFA
andPFA
we e hepoin so o ceapplica iono he on and ea
senso s, espec i ely.Thedis ancebe weenSki_2andPFA
was𝑚,and hedis ancebe weenPFA
andPFA
was𝑛.
Senso s2022,22,27775o 14
2.4.1.T ans o ming heFo cesMeasu ed om heFo ceSenso in o heGCSand hePFA
The o cesgene a ed om he olle ski o cecoo dina esys em(FCS)we e
ans o medin o heGCS.Theuni ec o o eachaxiso FCS(ı
,ȷ,k
)wasiden i iedby
ma ke son he olle ski(Figu e3).The ans o ma ion om he olle skisys em o he
GCSisgi enby
F
F
FRF
0
F⑴.
whe eFx,Fy,andFza e hecomponen so o cesgene a ed omlegs(F
)in heGCS.R
[18]is he o a ionma ix omFCS oGCS.
ThePFAisneeded o calcula ing he ansla ional o cein oducedbyGöp e e al.[6].
Thedisplacemen o hePFAalong hebinding(PFAski)wascalcula ed om he o ce
dis ibu ionbe ween he on and ea senso so hebinding[20]o e ime.ThePFA o each
pa o hebinding(PFA andPFA )wasde inedas hecen e o eachsenso .Thedis ance
be ween hema ke Ski_2andPFA (𝑚),and hedis ancebe weenPFA andPFA (𝑛)we e
measu edbe o e hemeasu emen .Thedisplacemen so PFA andPFA inGCSwe e
ob ainedbymo ing hemidpoin o Ski_2andSki_3along heopposi edi ec iono ȷ.The
mo ingdis anceswe e𝑚and𝑚𝑛, espec i ely.Themediola e alswayo PFAskionski
bindingwasno conside edin hiss udy.Thus, hePFAskimo edbe ween hePFA andPFA
(Figu e3).
Themeasu edaxialpole o ces(F
)we econside ed heGRFsac ingalong hepole
om he ip o he opo hepoleandexp essed ha wayin heGCS.Themagni udeo
F
wascollec edusingapole o cesenso .Thedi ec iono F
wasde inedusing he
e lec i ema ke s ha we ea ached o hepole.ThePFAo poles(PFAp)wasde inedas
hein e sec iono heplaneo he eadmilland helongaxiso hepole.Theplaneo he
eadmillwasde inedusing he h eema ke sa ached o he eadmill.
2.4.2.TheRe e enceFo ce, heTo alResul an Fo ce,and heT ansla ionalFo ce
Asusing hesegmen alme hodhasbeenshown obesui able o es ima ing he
posi iono heCOMinspo s[2], o cescalcula edbyCOMaccele a ion(a
)mul iplied
he o almasso hesubjec ,and heequipmen was he e e ence o ce(F
)in hiss udy.
Oneapp oach oes ima e o cesac ingonskie ’sCOMis ocalcula e he o al
esul an o ce(F
)wi hou conside ing heposi iono COM.F
iscalcula edas
F
F
F
F
G
⑵.
whe eG
is heg a i a ional o ceo eachpa icipan andall heequipmen .F
is he
ic ional o cebe ween he olle skiand he eadmill,whichwasdi ec edalong hepa h
o heskimo ion,and hemagni udewascompu edbymul iplyingμwi hF.
Ano he app oach oes ima e o cesac ingonskie ’sCOMis ocalcula e he o al
ansla ional o ce( hemechanicalp incipleo ansla ional o ce,seeAppendixB).The
ansla ional o ceis hesha eo he esul an GRFac ingin hedi ec ion omPFA o
COM.The ansla ional o ce omskis(F
,Figu e4)is hesha eo skiGRF(F
)ac ingin
hedi ec ionde ined omPFAski oCOMandiscalcula ed om
F
F
•u
u
⑶.
whe eu
is heuni ec o de e mined omPFAski oCOM.The ansla ional o ce om
poles(F
)iscalcula ed om
F
F
•
⑷.
Senso s2022,22,27776o 14
whe e
is heuni ec o de e mined omPFA
p
oCOM.The o al ansla ional o ce
(F
)is hesumo he ansla ional o ce om helegs,poles,and he esis ance.Thus,
F
canbecompu edas
F
F
F
F
G
⑸.
As o cesac ingonskie ’scen e o mass(COM)in o wa ddi ec iona e hep opul‐
si e o ces, heYcomponen o F
,F
,andF
(F,F
ne
,andF
p o
)wascompa edandana‐
lyzedin hep esen s udy.
Figu e4.Diag amo o cedecomposi ion omskis.F
is he esul an o cegene a ed omlegs.
F
is he ansla ionalcomponen ,whichwen h ough heCOM.F
ep esen s hep opulsion
gene a ed omlegsin he o wa ddi ec ion.
2.4.3.CycleDe ini ionandAnalyzedPa ame e s
A o alo 10consecu i epolingphases o eachDP echnique ialand10consecu i e
kickingphases(5le skikickingand5 igh skikicking) o eachV2 echnique ialwe e
analyzed.Thepolingphasewasde inedas hepe iod om hes a o hepoleg ound
con ac o heendo hepoleg oundcon ac (Figu e5a).Thekickingphasewasde ined
as heski o ceminimaun il heendo g oundcon ac [7](Figu e5b).The o ceso skis
andpoles ombo h hele and igh sideswe eincludedwhilecalcula ing he o alp o‐
pulsioninbo h echniques.
Theposi i esqua e oo o headjus edcoe icien o mul iplede e mina ion,which
is headjus edcoe icien o mul ipleco ela ion(CMC,0<CMC<1)[21,22],wascalcu‐
la ed o e alua ing hesimila i yo o ce– imecu es.Onecompa isonwasbe weenF
ne
andF o ce– imecu es.Thesimila i ybe weenF
ne
andFwas ep esen edbyCMC
ne
.
Themean o cedi e enceandmeanabsolu e o cedi e encebe weenF
ne
andFwe e
M
andM
||
.Ano he compa isonwasbe weenF
p o
andF o ce– imecu es.The
simila i ybe weenF
p o
andFwas ep esen edbyCMC
p o
.Themean o cedi e enceand
meanabsolu e o cedi e encebe weenF
p o
andFwe eM
andM
.Themean
o cedi e encesandmeanabsolu e o cedi e enceswe ecompu edo e o cecu es
a e agedo e 10 o ce‐p oducingphases.Themean o cedi e ences,whicha eM
andM
,we ecalcula ed op o idedesc ip i es a is icsonly.The o cesin hiss udy
we ep esen edas alues ela i e obodyweigh (%BW).
Senso s2022,22,27777o 14
Figu e5.De ini iono he o cep oducingphaseo DPandV2 echniques:(a)GRFs omskisand
polesin heDP echniqueand hede ini iono hepolingphase.(b)GRFs omskisandpolesin
heV2 echniqueand hede ini iono hekickingphase.
2.5.S a is icalAnalyses
A wo‐waymixed ac o ialANOVAwaspe o med.Thedependen a iableso he
analyseswe e(1)CMCsand(2)meanabsolu e o cedi e ences.Theindependen a iables
we e hespeed(o heincline)o he eadmilland hecompa isons(i.e.,compa isonbe‐
weenF
ne
andFandcompa isonbe weenF
p o
andF).Thespeed(o heincline)o he ead‐
millwas ea edas hewi hin‐subjec ac o ,and hecompa isonpai was ea edas he
be ween‐subjec ac o .TheEMMEANSsubcommandwi h heBon e oniadjus men in
SPSSwasused ope o m hepai wisecompa isonso hedependen a iablewhenin e ‐
ac ionswe ede ec ed[23],and hee ec size(
p
η
2
)wascalcula ed o u he e alua ion.The
le elo s a is icalsigni icancewasse a α=0.05.Allda aa ep esen edasmean±s anda d
de ia ion(SD).Da aanalyseswe econduc edusing e sion23.0o heSPSSp og ampack‐
age o s a is icalanalysis(SPSSInc.,Chicago,IL,USA).
3.Resul s
The o ce– imecu eso F,F
ne
,andF
p o
o heDPand heV2 echniquesa eshown
inFigu e6.Thein e ac ione ec (compa ison*speed)wassigni ican onCMCwi h he
DP echnique(p=0.038),bu no wi h heV2 echnique(p=0.988).CMC
p o
didno di e
omCMC
ne
a anyspeedin heDP echnique(p≥0.106,Table1).Wi h heV2 echnique,
heo e allCMC
p o
wasabou 5%lowe hanCMC
ne
(p=0.011,Table1).Thein e ac ion
e ec (compa ison*incline)wasno signi ican onCMCin heDP echnique(p=0.620)
bu wassigni ican in heV2 echnique(p=0.042).In heDP echnique, hemaine ec o
compa isononCMCwasno signi ican (p=0.218,Table1).In heV2 echnique,CMC
ne
wassigni ican lyg ea e hanCMC
p o
a 3°(p=0.042,Table1).
Ona e age, heM
waslowe hanze oand heM
wasg ea e hanze o
(Figu e7) o bo h heDPandV2 echniquesa anyspeedsandanyinclines.Thein e ac ion
e ec (compa ison*speed)wassigni ican on heabsolu emean o cedi e encewi h he
DP echnique(p=0.025)bu no wi h heV2 echnique(p=0.165).In heDP echnique,
M
||
was24%lowe hanM
a 15km/h(p=0.028,Table2).Fo heV2 echnique,
heo e allM
wasabou 37%g ea e hanM
|
Fne F
|
.
Thein e ac ione ec (compa i‐
son*incline)wasno signi ican onabsolu emean o cedi e encein heDP echnique(p=
0.393)bu wassigni ican in heV2 echnique(p=0.016).In heDP echnique, heo e all
M
||
wasabou 39%lowe hanM
.Wi h heV2 echnique,M
|
Fne F
|
wassigni i‐
can lylowe hanM
a 3°and4°(p≤0.013,Table2).
Wi h heDP echnique,CMC
p o
wasindependen om hespeed(p=0.371,Table1).
Howe e ,CMC
ne
dec easedsigni ican lya 21km/hwhencompa ed oCMC
ne
a 13,15,
and17km/h(p≤0.046).Theo e allCMCinc easedbyabou 2% om3 o5°.Bo h
Senso s2022,22,27778o 14
M
||
andM
inc easedwi h heinc easingspeedo he eadmill(p<0.001,p<
0.001,Table2).Theo e allabsolu emeandi e enceinc easedby23% om3 o5°.Wi h
heV2 echnique, heo e allCMCdec easedbyabou 2% om13 o21km/h.CMC
ne
wasindependen o heinclineo he eadmill(p=0.042,Table1).CMC
p o
inc eased om
3 o5°(p=0.007,Table1).Theo e allabsolu edi e enceinc easedby33% om13 o21
km/h.M
|
Fne F
|
wasdependen on heinclineo he eadmill(p=0.014,Table2),and
M
wasindependen o heinclineo he eadmill(p=0.577,Table2).
Figu e6.Fo ce‐ imecu eso F,F
ne
,andF
p o
:(a)DP echnique.(b)V2 echnique.Valuesa ea e ‐
agedo e 10 o ce‐p oducingphaseso onesubjec omeach echnique(speedo he eadmillwas
19km/h;inclineo he eadmillwas2°).
Figu e7.Mean o cedi e enceo e o cep oducingphasesinDPandV2 echniques
(%BW).M
ep esen s hedi e encebe weenFandF
ne
andiscalcula edbyF–F
ne
.
M
lowe hanze oindica es ha F
ne
isg ea e hanF.M
ep esen s hedi e ‐
encebe weenFandF
p o
andiscalcula edbyF–F
p o
.M
g ea e hanze oindica es
ha F
p o
islowe hanF.
Table1.Meanands anda dde ia iono heCMC o heDP echnique(n=9)and heV2 echnique
(n=10).
DPTechniqueV2Technique
CMC
ne
CMC
p o
p‐ValuePη
2
CMC
ne
CMC
p o
p‐ValuePη
2
Speeds
13km/h0.935±0.0220.910±0.0380.106
b
0.1550.901±0.0480.853±0.043
15km/h0.933±0.0230.916±0.0340.230
b
0.0890.908±0.0470.862±0.050
17km/h0.920±0.0300.919±0.0300.951
b
0.0010.905±0.0400.861±0.0350.011
a
0.309
19km/h0.901±0.0450.908±0.0460.778
b
0.0050.885±0.0450.837±0.047
21km/h0.883±0.058
1,2,3
0.907±0.0420.330
b
0.0590.879±0.0440.832±0.041
p‐ alue0.043
d
0.371
d
0.008
c
Pη
2
0.5090.264 0.216
Inclines3°0.933±0.0240.914±0.046 0.911±0.0320.856±0.0730.042
b
0.210