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Différences de recrutement musculaire entre le front squat et le back squat

18/06/2013 | Musculation des fessiers et Musculation des quadriceps et Musculation des ischio-jambiers et Etudes Musculation

 

ACTIVATION OF LOWER-EXTREMITY MUSCULATURE DURING VARRIED SQUAT CONFIGURATIONS: COMPARING FRONT AND BACK SQUATS
B. CAMPBELL   Journal of Strength and Conditioning Research       VOLUME 27 | SUPPLEMENT 4 | APRIL 2013 | S73

There is limited information available comparing changes in
muscle activity among these two squat configurations. This is
especially true when both variations of the back squat (high-bar
and low-bar) are compared with the front squat. Purpose: To
evaluate the muscle activation levels in select lower extremity
muscles during a high-bar back squat, a low-bar back squat,
and a front squat.

Methods: Eleven recreationally trained individuals
(8 males and 3 females) between the ages of 19 and 25
yrs participated. Eligibility was dependent upon the following
criteria: being able to squat to parallel, squat 75% of one’s bodyweight,
and have participated in squat exercises regularly within
the past year. One session was used to collect all of the EMG
data. The muscles examined were the rectus femoris, biceps
femoris, gluteus medius, and vastus medialis. Parallel squat
depth was controlled by electronic beepers placed on the thigh
of each participant. The participants performed five bodyweight
squats for a baseline measurment while EMG data was being
sampled. Each participant then performed one set of five repetitions
of each squat variation (HBS – high bar back squat, LBS –
low bar back squat and FS – Front Squat) with 75% of their
bodyweight loaded on a standard Olympic barbell. Two minutes
of rest was provided between squat variations and the order of
squat variations was randomized. The EMG data for all participants
was processed and smoothed using a 50 ms moving
window RMS. The mean EMG value for the middle three repetitions
of each squat condition was evaluated and normalized to
the body weight squat condition yielding a percent change from
the body weight condition (i.e. normalized mean EMG activity).

Results: The front squat (FS) elicited the greatest normalized
mean EMG activity for the biceps femoris and gluteus medius
(202.8% and 201.7%, respectively). The low-bar squat (LBS)
elicited the greatest normalized mean EMG activity for the rectus
femoris and the vastus medialis (176% and 185.6%, respectively).

Conclusions: Our preliminary findings demonstrate that
the FS elicited greater normalized mean EMG activity for the
biceps femoris while the LBS elicited greater normalized mean
EMG activity for the rectus femoris and vastus medialis. While it
was not directly measured in this study, a plausible explanation
for this initial finding is that the placement of the barbell during
the LBS shifted the COM posteriorly thereby eliciting more anterior
thigh (RF and VM) muscle activity, whereas the FS shifted the
COM anteriorly causing the posterior thigh (BF) musculature to
become more active to control the increased hip flexion moment.
Additionally, it may be appropriate to evaluate frontal plane knee
and hip kinematics during these squat variations in future studies
as it appears that the increase in gluteus medius activity during
the FS trials could be linked to an increased demand in hip
adduction and or knee valgus control.

Practical Applications:
Given these results it may be possible to use specific squatting
techniques to focus on specific lower extremity musculature. For
example, an athlete that suffers from a hamstring injury may
want to perform the LBS which seems to increase the amount
of quadriceps muscle activity and may reduce the hamstring
demand. Conversely, a person with weak or injured quadriceps
may want to perform FS which seems to increase hamstring
demand.

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