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Volume 5, Issue 3, December 2016 | JOURNAL OF FITNESS RESEARCH 57
ISSN 2201-5655 © 2016, Australian Institute of Fitness
ORIGINAL RESEARCH
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ABSTRACT
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HJ[P]P[`T\KKSLZV\Y\UKLYZ[HUKPUNVMT\ZJSLYLJY\P[TLU[PU[OLIHJRZX\H[;OPZZ[\K`KL[LYTPULK,4.
HJ[P]P[`HZHM\UJ[PVUVMZX\H[KLW[OPUMV\YZ\WLYÄJPHST\ZJSLZVM[OLSV^LYSPTI\ZPUNYLSH[P]LSVHKPUN
4L[OVK!,PNO[YLZPZ[HUJL[YHPULKTHSLZTLHU:+HNL!`LHYZWLYMVYTLKIHJRZX\H[Z[VWHY[PHS
WHYHSSLSHUKM\SSKLW[O\ZPUNKLW[OYLSH[P]LYLWL[P[PVU¶TH_PT\TSVHKZ4\ZJSLHJ[P]P[`PU[OL]HZ[\Z
TLKPHSPZVISPX\L=46]HZ[\ZSH[LYHSPZ=3NS\[L\ZTH_PT\Z.4HUKIPJLWZMLTVYPZ)-K\YPUN[OL
JVUJLU[YPJHUKLJJLU[YPJWOHZLZVM[OLZX\H[^HZKL[LYTPULK\ZPUNZ\YMHJLLSLJ[YVT`VNYHWO`7LHR7LHR
,4.TLHU4LHU,4.HUKPU[LNYH[LKP,4.,4.UVYTHSPZLK[V[OLPYYLZWLJ[P]LTH_PT\T]VS\U[HY`
PZVTL[YPJJVU[YHJ[PVU4=0*MVYLHJOT\ZJSL^LYLL]HS\H[LK
Results: ;OYLL^H`(UV]HZHUK:PKHRWVZ[OVJHUHS`ZPZYL]LHSLKZPNUPÄJHU[LɈLJ[ZMVYZX\H[[`WLW$
ZX\H[WOHZLW$HUKT\ZJSLW$;OLZPNUPÄJHU[KPɈLYLUJLZ^LYLIL[^LLU[OL
WHY[PHSHUK[OLWHYHSSLSZX\H[W$"MVYP,4.ZPNUPÄJHU[LɈLJ[Z^LYLHSZVMV\UKIL[^LLU[OL
WHY[PHSHUKM\SSZX\H[W$;OL=46LSPJP[LK[OLOPNOLZ[,4.HJ[P]P[`LN7LHR,4.
4=0*"WHYHSSLSZX\H[JVUJLU[YPJHUK[OL)-[OLSV^LZ[LN7LHR,4. .YLH[LY.4HJ[P]P[`
VJJ\YYLKPUWHYHSSLSZX\H[ZJVTWHYLK[VM\SSZX\H[ZTLHUKPɈLYLUJLPU7LHR,4.$ 4=0*
Conclusion:;OLÄUKPUNZZ\NNLZ[[OH[ZX\H[[PUN[V[OLWHYHSSLSWVZP[PVUVYSV^LYPUK\JLZVW[PTHSJVU[YHJ[PSL
Z[PT\SH[PVUVM[OLX\HKYPJLWZ:X\H[[PUN[VWHYHSSLSKLW[OTH_PTPZLZ,4.HJ[P]H[PVUVM[OL.4WVZZPIS`K\L
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VISPX\L
Volume 5, Issue 3, December 2016 | JOURNAL OF FITNESS RESEARCH 58
INTRODUCTION
The free barbell back squat is a closed-chain,
multi-joint movement frequently incorporated into
the strength and conditioning programmes of
athletes 1,2,WLVLPSHUDWLYHWKDWFRDFKHVDUHHTXLSSHG
with underlying research evidence regarding the
contribution of different muscles of the lower limb
WRWKHVTXDW,QVWUHQJWKWUDLQLQJSURJUDPVYDULDWLRQV
in the lifting technique are applied in an attempt to
target certain muscle groups by altering the joint
torques 3,4+RZHYHUWKHSK\VLRORJLFDOVWUHVVHV
associated with high levels of muscle activity and
time-under-tension are central to stimulating a
training effect 5; simply shifting joint torques does
QRWJXDUDQWHHDXJPHQWDWLRQVLQPXVFOHÀEUH
UHFUXLWPHQW)RUWKLVUHDVRQVXUIDFH
HOHFWURP\RJUDSK\(0*LVFRPPRQO\HPSOR\HGWR
determine the potential effectiveness of an exercise
variation and the associated neuromuscular adaptive
stimulus 6; whereby, measures typically include peak
3HDN(0*PHDQ0HDQ(0*DQGLQWHJUDWHG
L(0*(0*QRUPDOLVHGWRPD[LPXPYROXQWDU\
LVRPHWULFFRQWUDFWLRQ09,&$OWHULQJWKHGHSWKWR
which an athlete descends in the squat is one
approach that may permit favourable outcomes in
muscle activity and concomitant physiological
perturbations, and hence optimise neuromuscular
DGDSWDWLRQVLQDWKOHWHV([LVWLQJOLWHUDWXUHVXSSRUWV
that small alterations in squat technique can impact
on the muscle activity evoked 77KHWKUHHVTXDW
depths most commonly adopted in strength training
are the partial squat, parallel squat, and full squat 8,9
It has been reported that with increased hip and
NQHHÁH[LRQLQWKHVTXDWUHODWLYHPXVFXODUHIIRUWDW
these joints increases in the concentric phase 5$Q
increase in muscle activity and concomitant stimuli
IRUQHXURPXVFXODUDGDSWDWLRQKDVEHHQLPSOLHG
+RZHYHU%U\DQWRQet al. 5 used inverse dynamics to
compute net joint moments and an isokinetic
dynamometer matched for joint angle at each squat
depth to establish a maximal force for relative
FRPSDULVRQVDQG(0*DQDO\VLVZDVQRWXVHG-RLQW
moments are a product of both mechanical leverage
and muscle tension, and involve all muscles acting to
SURGXFHH[WHQVLRQDERXWWKHMRLQW7RWKLVHQG(0*
analysis must be employed for the analysis of the
VTXDW7KHRQO\LQYHVWLJDWLRQRQWKHPXVFXODUDFWLYLW\
RI WKH*OXWHXV0D[LPXV*0DWGLIIHUHQWVTXDW
depths is the research by Caterisano and colleagues
10,QWKHLUDQDO\VLVRI WKH*0YDVWXVPHGLDOLV
REOLTXH902YDVWXVODWHUDOLV9/DQGELFHSV
IHPRULV%)WKHDXWKRUVIRXQGRQO\WKH*0WR
EHFRPHVLJQLÀFDQWO\PRUHDFWLYHZLWKGHSWKLQ
partial, parallel and full squats during the concentric
SKDVHL(0*DQG09,&
UHVSHFWLYHO\1RQHWKHOHVVRXUXQGHUVWDQGLQJRI *0
FRQWULEXWLRQWRWKHVTXDWLVOLPLWHG
Previous research report that lifted load decreases
with squat depth due to mechanical factors that
include a greater range of motion through which the
load must be moved and thus an increased time
under tension and concomitant demands on the
muscle, and an unfavourable length-tension
relationship created by the increased muscle lengths
RI WKHYDVWLDQG*097KHUHIRUHDFRPSOH[FRQWURO
strategy is required in the squat movement since the
joint moments, muscle activity, relative contribution
of the lower limb joints, and lifted load are
LQÁXHQFHGE\VTXDWGHSWK11,128QFRYHULQJD
limitation of previous research 10, the same absolute
EDUEHOOORDGZDVXVHGIRUHDFKVTXDWGHSWK
Therefore, the maximum exercise intensity possible
at each depth was not used; posing implications for
muscle activity 1,57KHJUHDWHULQWHQVLWLHVDVVRFLDWHG
with increased squat depth would thereby ostensibly
elicit greater muscle activity in the prime movers 5,7
DQGSRLQWWRWKHQHHGIRUIXUWKHUUHVHDUFK
5HVHDUFK13 found a sudden increase in hip and
NQHHH[WHQVRU(0*DFWLYLW\GXULQJWKHLQLWLDODVFHQW
from full squats, consistent with pertinent literature
regarding increases in activity after transitioning from
the eccentric to the concentric phases of the
movement 2,4+RZHYHUWKHUHVXOWVRI 5REHUWVRQet
al13GHSLFWDJUDGXDOLQFUHDVHLQ*0DFWLYLW\
WKHUHDIWHUDSSDUHQWRYHUWKHÀUVWWZRWKLUGVRI WKH
DVFHQW7KLVVXJJHVWVWKDW3HDN(0*DFWLYLW\RI WKH
*0PD\EHDWWDLQHGE\VTXDWWLQJWRDSDUWLDORU
parallel depth only; however, the study does not
compare muscle activity between squats to different
GHSWKVZDUUDQWLQJIXUWKHUUHVHDUFK
Unlike the quadriceps femoris, which have
demonstrated near maximal levels of recruitment
Volume 5, Issue 3, December 2016 | JOURNAL OF FITNESS RESEARCH 59
during full squats 13, hamstring activity during the
EDFNVTXDWLQFOXGLQJWKDWRI WKH%)LVVHHPLQJO\ORZ
ZLWKVWXGLHVKDYLQJUHSHDWHGO\GRFXPHQWHGWKH%)DV
contributing minimally to the movement in terms of
DEVROXWH(0*7,14)RULQVWDQFH(EEHQ14VKRZHG
times less activity in the hamstrings muscles relative
to the quadriceps; however, squat depth comparisons
DUHODUJHO\DEVHQW*RUVXFKDQGFROOHDJXHV15
examined the effect of squat depth on the
P\RHOHFWULFDODFWLYLW\RI WKH%)DQGUHSRUWHGRQO\
PDUJLQDODQGVWDWLVWLFDOO\QRQVLJQLÀFDQWGLIIHUHQFHV
LQ(0*DFURVVVTXDWGHSWKFRQGLWLRQVRQO\SDUWLDO
P9DQGSDUDOOHOP9
VTXDWGHSWKVZHUHFRPSDUHG)XUWKHUUHVHDUFKLV
UHTXLUHGWRXQYHLOWKH(0*SDWWHUQVRI WKH
KDPVWULQJVDVDIXQFWLRQRI VTXDWGHSWK
)URPWKHDYDLODEOHOLWHUDWXUHRQHFDQGHGXFHWKDW
the vasti are moderately-to-highly active, while the
%)LVPLQLPDOO\DFWLYHLQWKHSDUDOOHOVTXDW2,4/LPLWHG
UHVHDUFKKDVLQYHVWLJDWHGPXVFOHDFWLYLW\RI WKH*0
in the back squat 13$OVRWKHOLWHUDWXUHLVHTXLYRFDO
UHJDUGLQJ(0*DFWLYLW\DWYDU\LQJVTXDWGHSWKV
0XVFOHUHFUXLWPHQWLVKLJKO\GHSHQGHQWRQEDUORDG
7+RZHYHUIHZ(0*VWXGLHVKDYHH[SORUHG
LQWHQVLWLHVJUHDWHUWKDQUHSHWLWLRQPD[LPXP50
in the back squat; intensities which are most
conducive to maximal strength development 16
Therefore, the aim of this study was to determine
(0*DFWLYLW\RI WKH9029/*0DQG%)PXVFOHV
at different depths of the back squat using relative
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IRURSWLPLVDWLRQRI VTXDWWUDLQLQJ
METHODOLOGY
Experimental Design
Participants were requested to attend three data
collection sessions separated by at least 72 hours to
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VHVVLRQDQGGHWHUPLQDWLRQRI ÀYHUHSHWLWLRQ
PD[LPXP50ORDGVWHVWVIRU09,&DQG
H[SHULPHQWDOVHVVLRQ,QGHSHQGHQWYDULDEOHVLQFOXGHG
VTXDWGHSWKSDUWLDOVTXDWSDUDOOHOVTXDWDQGIXOO
VTXDWVTXDWSKDVHFRQFHQWULFDQGHFFHQWULFDQG
PXVFOH9029/*0DQG%)7KHGHSHQGHQW
YDULDEOHVZHUH3HDN(0*0HDQ(0*DQGL(0*
3HDN(0*DOORZVIRUWKHKLJKHVWOHYHODQGQHDU
instantaneous changes in muscle activation to be
REVHUYHG0HDQ(0*LVUREXVWWRERWKPRYHPHQW
DUWHIDFWDQGWLPHWKXVSURYLGLQJDUHOLDEOH(0*
amplitude over the entire movement 177KHL(0*
best illustrates mechanical work performed by the
PXVFOH7KHSDUWLDOVTXDWZDVGHÀQHGE\DIHPXUWR
VKDQNDQJOHRI DSSUR[LPDWHO\)LJXUH7KH
SRVLWLRQDWZKLFKWKHIHPXUZDVSDUDOOHOWRWKHÁRRU
GHQRWHGWKHSDUDOOHOVTXDW7KHIXOOVTXDWZDV
determined based on the acetabulofemoral joint
distinctly below the horizontal plane of the knee
ZKLOVWZLWKLQWKHPRELOLW\FRQÀQHVRI WKHSDUWLFLSDQW
LHPDLQWDLQLQJKHHOFRQWDFWZLWKWKHJURXQG16$W
the instant the desired squat depth was reached, an
investigator situated to the side of the participant
provided verbal cues to participants instigating the
concentric portion of the lift; video analysis was used
to verify that each depth was achieved 107RDFFRXQW
for circadian variations 6, experimental testing and
09,&WULDOVZHUHXQGHUWDNHQFRQVLVWHQWO\EHWZHHQ
••
Figure 1. Partial (a), parallel (b) and full squat (c) depths.
Volume 5, Issue 3, December 2016 | JOURNAL OF FITNESS RESEARCH 60
WKHKRXUVRI DPDQGSP)XUWKHUPRUH
participants were asked to abstain from any lower
body resistance training or exhaustive activity in the
48 hours preceding all testing to ensure no muscle
soreness was present that may have compromised
WKHYDOLGLW\RI WKHGDWD7HVWLQJZDVFRQGXFWHGXVLQJ
a randomised and counterbalanced repeated
measures design to mitigate order effects 18
Participants
(LJKWKHDOWK\PDOHVRI PHDQ6'DJHRI
years, height of 176 ± 5 cm, mass of 80 ± 9 kg, and
training experience in the free barbell back squat of 5
\HDUVZHUHUHFUXLWHG([FOXVLRQFULWHULD
encompassed a history of lower body injury or
SDWKRORJ\WKDWPD\LQÁXHQFHSDWWHUQVRI DFWLYDWLRQ
LQORZHUERG\PXVFXODWXUH,QVXIÀFLHQWGRUVLÁH[LRQ
preventing full squat depth reached safely using
correct squatting technique was contraindicated 19, as
ZDVH[FHVVLYHOXPEDUÁH[LRQDWWULEXWDEOHWRLQKHUHQW
anatomical or immobility induced posterior pelvic tilt
16&ULWHULDIRULQVXIÀFLHQWGRUVLÁH[LRQZDVDVVHVVHG
E\DQH[SHULHQFHG6WUHQJWK&RQGLWLRQLQJFRDFKE\
ascertaining whether the participants were able to
maintain heel contact with the ground during full
VTXDWVDQGH[FHVVLYHOXPEDUÁH[LRQZDVJDXJHG
visually by the coach based on own experience and
NLQHVLRORJLFDOHGXFDWLRQ7KHXVHRI HLJKW
participants elicited medium and large statistical
effect sizes 207KHVWXG\ZDVDSSURYHGE\WKH(WKLFV
&RPPLWWHHDW(GJH+LOO8QLYHUVLW\
Squat Technique
Participants performed the back squat wearing
WKHLURZQFURVVWUDLQLQJVKRHVZLWKDÀUPDQGVWDEOH
VROH7KHIHHWZHUHSRVLWLRQHGVOLJKWO\ZLGHUWKDQ
shoulder width apart while maintaining a naturally
QHXWUDORUVOLJKWO\DEGXFWHGRULHQWDWLRQ)RRW
SRVLWLRQZDVVWDQGDUGLVHGEHWZHHQWULDOV7KHEDUEHOO
was held using a pronated grip at a width as narrow
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permit, and placed behind the neck across the upper
WUDSH]LXVLQWKH¶KLJKEDU·SRVLWLRQZLWKWKHVFDSXODH
retracted 16'XULQJWKHVTXDWWKHNQHHVZHUHDOLJQHG
with the toes and tracked them throughout the
PRYHPHQW$FXHIRUDEGXFWLRQDQGH[WHUQDO
rotation of the hips was given to facilitate this action
and mitigate gravity induced hip adduction torque
and deleterious knee valgus in the presence of
ORZHU²ERG\VWUHQJWKDQGPRELOLW\GHÀFLWV217KH
lumbar and thoracic spinal regions maintained their
natural or slightly extended curvatures throughout
the movement, with slight hyperextension of the
cervical spine, as participants faced forward 22
/XPEDUDQGWKRUDFLFVSLQDOFXUYDWXUHDQGIRUZDUG
lean were visually monitored by the experienced
6WUHQJWK&RQGLWLRQLQJFRDFK$YLVXDOLQGLFDWRURI
excessive forward lean was when the hips rose up too
quickly relative to the shoulders from the start of the
ascent, in which case the data were discarded and the
trial repeated 103DUWLFLSDQWVZHUHLQVWUXFWHGWR
´FRQWUROµWKHLUGHVFHQWDQGQRWWR´ERXQFHµRII
WKHLUFDOYHVLQWKHIXOOVTXDW1REHOWVRUNQHHZUDSV
were permitted due to their attenuation effect on
(0*DFWLYLW\1
Familiarisation Trial and 5RM Procedures
$50ORDGZDVVHOHFWHGDVUHSHWLWLRQVLV
common place in strength training programs and
within the recommended repetition range for
developing maximum strength 167KH50ORDGDW
each depth was used to allow the prescription of
relative loading 7'XULQJDIDPLOLDULVDWLRQVHVVLRQ
SDUWLFLSDQWVHVWDEOLVKHGWKHLU50WRWKHQHDUHVW
kg at each squat depth; ten minutes recovery was
SURYLGHGEHWZHHQWKH50WULDOV17KHSDUWLFLSDQWV
performed two warm up sets before attempting the
ÀUVWHVWLPDWHG50ORDGXVLQJDIUHH2O\PSLF
EDUEHOO7KUHH50VTXDWDWWHPSWVZHUHFDUULHGRXW
WRGHWHUPLQHWKH50DWHDFKGHSWK12:LWK
consideration to circadian rhythm 6DOO50WULDOV
WRRNSODFHEHWZHHQWKHKRXUVRI DPDQG
SP$WWDLQHG50ORDGVE\DOOSDUWLFLSDQWVUDQJHG
IURPWRNJSDUWLDOVTXDWWR
NJSDUDOOHOVTXDWDQGWRNJIXOOVTXDW
Electromyography Procedures
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ELSRODUFRQÀJXUHGSDVVLYHZHWJHOVXUIDFHHOHFWURGHV
ZHUHDIÀ[HGLQSDLUVVSDFHGPPDSDUWWRWKH
EHOO\RI HDFKPXVFOHDFFRUGLQJWR6(1,$0
guidelines and oriented parallel with the muscle
Volume 5, Issue 3, December 2016 | JOURNAL OF FITNESS RESEARCH 61
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of electrode placement was shaved, and cleansed
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connected to the electrodes via a two-snap lead and
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These modules housed a reference electrode which
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relayed wirelessly from the modules to the telemetric
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1RUD[RQ86$,QF$UL]RQD86$DQGVDPSOHGDW
+]7RRSWLPLVHWUDQVPLVVLRQVLJQDOVZHUHKLJK
SDVVÀOWHUHGXVLQJDEDQGSDVVDW+]$OO
(0*GDWDZDVVDYHGXVLQJWKHPDQXIDFWXUHU·V
VRIWZDUH0\RUHVHDFUK;31RUD[RQ86$,QF
$UL]RQD86$5DZ(0*WUDFHVZHUHIXOOZDYH
UHFWLÀHGDQGVPRRWKHGXVLQJDURRWPHDQVTXDUH
506DOJRULWKPZLWKDPVWLPHZLQGRZ3HDN
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QRUPDOLVHGWR09,&WULDOV17
MVICs
7KH09,&VDWHDFKPXVFOHRI LQWHUHVWZHUH
SHUIRUPHGWRREWDLQDUHIHUHQFH(0*GHQRPLQDWRU
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normalisation technique 24 and its exclusivity in
providing estimates of the degree of motor-unit
recruitment relative to a muscle’s maximum
activation potential, permitting comparisons between
muscles 18,237KHIROORZLQJWDVNVKDYHEHHQLGHQWLÀHG
as eliciting maximum muscle activity and were
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was performed with the participants assuming a
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approximately 90° and full extension of their right
hip 217KHYDVWL09,&VZHUHDFKLHYHGZKLOHVHDWHG
RQDFRPPHUFLDOJ\PEDVHG¶OHJH[WHQVLRQ·PDFKLQH
/LIH)LWQHVVZLWKWKHULJKWNQHHDQGKLSVÁH[HGWR
approximately 60° and 90°, respectively 25$SSO\LQJ
a resistance great enough to deny movement, a
maximum effort knee extension was then performed
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09,&ZDVFRPSOHWHGDWFLUFDRI NQHHÁH[LRQ
DQGRI KLSÁH[LRQZKLOHVHDWHG25,26; though a
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pad placed atop the upper thighs prevented any
unwanted movement of the thighs or hips during the
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cue to contract the muscle as quickly as possible 1
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520UHSHWLWLRQVWKUHHÀYHVHFRQGPD[LPDO
isometric efforts were performed for each muscle
group, intervened by a minimum of two minutes to
lessen fatigue effects 17KHKLJKHVW(0*UHDGLQJ
obtained from these repetitions subsequently
denoted the normalisation reference for the
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Experimental Procedures
Participants undertook a standardised warm-up,
comprising activation exercises, dynamic stretching
DQGXQZHLJKWHG2O\PSLFEDUEHOOVTXDWVEHIRUH
incremental warm-up sets of 6 repetitions at 40%,
DQGRI WKHLUÀUVWWHVWHGVTXDWGHSWK50
XVLQJDVWDQGDUGNJ2O\PSLFEDUEHOO276XFFHHGLQJ
the warm-up, participants performed 3 consecutive
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repetitions, rather than 5, were used to circumvent
possible fatigue induced deterioration of technique
that may affect relative muscle contribution during
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set up perpendicular to the line of action at
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IURPWKHEDUDQGV\QFKURQLVHGWRWKH(0*WUDFHIRU
DQDFFXUDWHLQWHUSUHWDWLRQRI UHVXOWV7KLVLQFOXGHG
the partitioning of data into respective concentric
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VTXDWGHSWK$OOWKUHHWULDOVZHUHSHUIRUPHGGXULQJ
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variable physiological and biochemical states and
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H[DFWSRVLWLRQVRQWKH(0*VLJQDODQG
consequentially compromising the reliability of data
23,247KLVWHFKQLTXHKDVSUHYLRXVO\GHPRQVWUDWHG
KLJKLQWUDFODVVFRUUHODWLRQFRHIÀFLHQWV,&&V
IRUWKLJKDQGKLSPXVFXODWXUHLQWKH
back squat 29(DFKWULDOZDVLQWHUVSHUVHGZLWKWHQ
minutes of rest to allow fatigue to fully dissipate and
DQ\UHV\QWKHVLVRI $733&UVWRUHVWRRFFXU17KH
back squat was performed inside a power rack, while
Volume 5, Issue 3, December 2016 | JOURNAL OF FITNESS RESEARCH 62
two spotters, one at each end of the barbell, were
present during each lift to ensure safety 16
Statistical Analyses
6WDWLVWLFDODQDO\VLVZDVFDUULHGRXWXVLQJ,%06366
VRIWZDUH,%0$VVHVVPHQWRI WKH
normality of raw data assumption was performed
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44SORWV$VVHVVPHQWRI WKHQRUPDOLW\RI UHVLGXDOV
and homogeneity of residuals assumptions was
DFFRPSOLVKHGXVLQJ44SORWVDQGVFDWWHUJUDSKVWR
inspect homoscedasticity, and Cook’s distance 305DZ
data were mathematically transformed using a
ORJDULWKPLFIXQFWLRQ7KUHHZD\$QRYDVZHUH
SHUIRUPHGZKHUHLQ3HDN(0*0HDQ(0*DQG
L(0*ZLWKLQVTXDWW\SHVVTXDWSKDVHVDQGPXVFOH
HIIHFWVZHUHFDOFXODWHGS6LGDNSRVWKRF
tests were performed on any measure that achieved a
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2 was
interpreted based upon the guidelines of 20; that is, a
Ƨp
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0
20
40
60
80
100
120
140
VMO VL GM BF
% M VIC
Muscle ( Concentr ic)
Partial Parallel Full
0
20
40
60
80
100
120
140
VMO VL GM BF
% M VIC
Muscle ( Eccentr ic)
Partial Parallel Full
0
20
40
60
80
100
120
140
VMO VL GM BF
% M VIC
Muscle ( Concentr ic)
Partial Parallel Full
0
20
40
60
80
100
120
140
VMO VL GM BF
% M VIC
Muscle ( Eccentr ic)
Partial Parallel Full
0
20
40
60
80
100
120
140
VMO VL GM BF
% M VIC
Muscle ( Concentr ic)
Partial Parallel Full
0
20
40
60
80
100
120
140
VMO VL GM BF
% M VIC
Muscle ( Eccentr ic)
Partial Parallel Full
Figure 2. Peak EMG presented as mean + SD normalised to
MVIC.
Figure 3. Mean EMG presented as mean + SD normalised to
MVIC.
Figure 4. iEMG presented as mean + SD normalised to MVIC.
Volume 5, Issue 3, December 2016 | JOURNAL OF FITNESS RESEARCH 63
SDUDOOHO902 9/ IXOO902
9/ )LJXUH7KHKLJKHUPXVFOH
activity of the vasti in the parallel compared to the
partial squat is likely due to the mechanical
disadvantage that occurs as a result of the initial
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reported 1 that during concentric contractions, neural
drive to the quadriceps is greater for intermediate
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the quadriceps femoris in the partial squat may in
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rates 11HJOLJLEOHGLIIHUHQFHVLQ(0*DFWLYLW\ZHUH
found between the parallel and full squats in both
YDVWLPXVFOHVIRUDOO(0*SDUDPHWHUV7KLVÀQGLQJLV
in agreement with Wretenberg and colleagues 31, who
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9/EHWZHHQSDUDOOHODQGIXOOVTXDWV+RZHYHU
5REHUWVRQ et al. 13IRXQGWKDWSHDN9/DFWLYLW\ZDV
maximum at the bottom of the squat suggesting that
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RESULTS
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by a progressive reduction in activity in the order
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Table 1: Statistically signicant results of the three-way Anova
and Sidak post-hoc statistical tests (Peak EMG).
Variables F
ratio df pȘp2power
Squat type 4.1 2,156 0.018 0.05 0.72
Squat phase 228.0 1,156 0.001 0.61 1.00
Muscle 101.0 3,156 0.001 0.67 1.00
Squat type * Phase 9.2 2,156 0.001 0.11 0.98
Squat phase * Muscle 10.3 3,156 0.001 0.17 1.00
Sidak post-hocs
Squat type
Partial vs. parallel 0.016
Muscle
VMO vs. GM 0.001
VMO vs. BF 0.001
VL vs. GM 0.001
VL vs. BF 0.001
GM vs. BF 0.001
Volume 5, Issue 3, December 2016 | JOURNAL OF FITNESS RESEARCH 64
IXUWKHU
7KHPRVWSURPLQHQWÀQGLQJZDVWKDWVTXDWWLQJWR
SDUDOOHOHYRNHGJUHDWHU3HDN(0*0HDQ(0*DQG
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Caterisano et al. 10ZKRUHSRUWHGWKH*0VLJQLÀFDQWO\
more active in the full squat, and the mechanical
DQDO\VLVFDUULHGRXWE\%U\DQWRQet al5 who reported
that the largest hip joint moment and relative
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RXUÀQGLQJVXEVWDQWLDWHVRWKHUUHSRUWV13 that found
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ERWWRPRI DIXOOVTXDWWRDSDUDOOHOGHSWK
7KHKLJKHU*0DFWLYLW\LQWKHSDUDOOHOVTXDWPD\
EHH[SODLQHGE\DQXPEHURI IDFWRUV([DPLQDWLRQRI
the time-motion analysis of the full squat 1 reveals
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appears to attenuate once the participant descends
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maximised and the femur to shank angle is reduced,
bringing the acetabulofemoral joint closer to the
vertical plane of the bar 17KLVREVHUYDWLRQVXEPLWV
WKDWOHVVWRUTXHDQGWKXVOHVV(0*DFWLYLW\RI WKH
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load compared to the parallel squat 22+RZHYHUQR
published kinematic data exists to substantiate this
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relative muscular effort of the knee extensor with
greater squat depth 5DQGKLJKHU902(0*DFWLYLW\
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muscle activity did not increase in the full squat is the
role of soft tissue in supporting the load at the end
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conducive to muscle force production 3 and
suggestive that perhaps less activation is required to
generate tension in the partial squat 22,WLVXQFOHDU
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depth and remains constant, whereby muscle length
and involvement would not necessarily change as the
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Table 2: Statistically signicant results of the three-way Anova
and Sidak post-hoc statistical tests (Mean EMG).
Variables F
ratio df pȘp2power
Squat type 3.9 2,156 0.021 0.05 0.70
Squat phase 205.6 1,156 0.001 0.57 1.00
Muscle 166.6 3,156 0.001 0.76 1.00
Squat type * Phase 4.9 2,156 0.009 0.06 0.80
Squat phase * Muscle 13.3 3,156 0.001 0.02 1.00
Sidak post-hocs
Squat type
Partial vs. parallel 0.07*
Muscle
VMO vs. GM 0.001
VMO vs. BF 0.001
VL vs. GM 0.001
VL vs. BF 0.001
GM vs. BF 0.001
* Approaching significance
Table 3: Statistically signicant results of the three-way Anova
and Sidak post-hoc statistical tests (iEMG).
Variables F
ratio df pȘp2power
Squat type 22.1 2,156 0.001 0.22 1.00
Squat phase 165.7 1,156 0.001 0.51 1.00
Muscle 112.8 3,156 0.001 0.68 1.00
Squat type * Phase 4.3 2,156 0.015 0.05 0.74
Squat phase * Muscle 9.5 3,156 0.001 0.15 1.00
Sidak post-hocs
Squat type
Partial vs. parallel 0.001
Partial vs. full 0.001
Muscle
VMO vs. GM 0.001
VMO vs. BF 0.001
VL vs. GM 0.001
VL vs. BF 0.001
GM vs. BF 0.001
Volume 5, Issue 3, December 2016 | JOURNAL OF FITNESS RESEARCH 65
7KH%)ZDVPRUHDFWLYHDWSDUDOOHO0HDQ(0*
09,&WKDQGXULQJSDUWLDOVTXDWV
during the concentric phase, similarly to the vasti and
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differences were found between parallel and full
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4 of 26 ± 11% and 2 of approximately 24% even
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the eccentric phase, both knee extensors were active
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reported previously 18RI DQG
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lower than those reported by the other studies, as is
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compared to other work 13, which is unexpected as
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Nonetheless, while the back squat provides an
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GHYHORSPHQWWKH%)LVPXFKOHVVDFWLYHGXULQJWKH
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risk from squatting below parallel have since been
dispelled and such forces are no longer considered
an issue when concerning a healthy knee joint 22,32
7KHÀQGLQJVRI WKHSUHVHQWVWXG\LQGLFDWHWKDWWKH
EDFNVTXDWZLOOSURGXFHKLJK902DQG9/UHODWLYH
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thus prompt a disproportionate development of
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must be cognizant of the necessity to incorporate
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imbalance in muscle activation and reduce the
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is associated with risk factors such as hamstrings
inhibition during antagonistic co-activation, reduced
knee joint stability and resulting anterior tibial
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susceptibility to injury 337KLVLVSDUWLFXODUO\
pertinent in female athletes in whom inherent
quadriceps to hamstrings dominance is apparent 34,
and highly applicable to athletic performance where
lateral cutting manoeuvres and landing forces
demand effective joint stability 35
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2 and high statistical power were achieved
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care was taken to ensure electrode placement sites
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days separate from the experimental trials which may
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To this end, it would be expedient to analyse trunk
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CONCLUSIONS
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squat provides an effective training stimulus for
902DQG9/GHYHORSPHQWPRGHUDWHVWLPXOXVIRU
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Thus, supplementary strength training exercises may
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full squats than in the partial squat during the
concentric phase, and in the eccentric phase with
UHJDUGVWRL(0*7KHKLJKHUPXVFOHDFWLYLW\RI WKH
vasti in the parallel compared to the partial squat is
likely due to mechanical disadvantage and greater
neural drive to the quadriceps at intermediate and
ODUJHPXVFOHOHQJWKVLHDWSDUDOOHODQGIXOOVTXDW
GHSWKVWKDQIRUVKRUWPXVFOHOHQJWKVLHSDUWLDO
VTXDWGHSWKDQGVXERSWLPDOPRWRUXQLWÀULQJUDWHV
LQWKHSDUWLDOVTXDW$PDMRUÀQGLQJZDVJUHDWHU*0
Volume 5, Issue 3, December 2016 | JOURNAL OF FITNESS RESEARCH 66
activity in parallel squats compared to full squats
which may be explained by a number of factors
related to external moment arm, relative muscular
HIIRUWDQGRSWLPDOOHQJWKWHQVLRQUHODWLRQVKLS
ACKNOWLEDGEMENTS
The authors would like to acknowledge the
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& Exercise.
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peak torque, and quadriceps and hamstrings
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