Article

Numerous studies have described 3D kinematics, 3D kinetics and electromyography
(EMG) of the lower limbs during quasi-static or dynamic squatting activities. One
study compared these two squatting conditions but only at low speed on healthy
subjects, and provided no information on kinetics and EMG of the lower limbs. The
purpose of the present study was to contrast simultaneous recordings of 3D
kinematics, 3D kinetics and EMG of the lower limbs during quasi-stat ic and
fast-dynamic squats in healthy and pathological subjects. Ten subjects were
recruited: five healthy and five osteoarthritis subjects. A motion-capture
system, force plate, and surface electrodes respectively recorded 3D kinematics,
3D kinetics and EMG of the lower limbs. Each subject performed a quasi-static
squat and several fast-dynamic squats from 0 degrees to 70 degrees of knee
flexion. The two squatting conditions were compared for positions where
quasi-static and fast-dynamic knee flexion-extension angles were similar. Mean
differences between quasi-static and fast-dynamic squats were 1.5 degrees for
rotations, 1.9 mm for translations, 2.1% of subjects' body weight for ground
reaction forces, 6.6 Nm for torques, 11.2 mm for center of pressure, and 6.3% of
maximum fast-dynamic electromyographic activities for EMG. Some significant
differences (p<0.05) were found in internal rotation, anterior translation,
vertical force and EMG. All differences between quasi-static and fast-dynamic
squats were small. 69.5% of compared data were equivalent. In conclusion, this
study showed that quasi-static and fast-dynamic squatting activities are
comparable in terms of 3D kinematics, 3D kinetics and EMG, although some
reservations still remain.
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Langue : ANGLAIS