Article

The purpose of this study was to investigate the neuromuscular efficiency of
women with knee osteoarthritis (OA) when performing a sit-to-stand movement and
during maximum strength efforts. Twelve women with unilateral knee OA (age
60.33+/-6.66 years, height 1.61+/-0.05 m, mass 77.08+/-9.2 kg) and 11 controls
(age 56.54+/-5.46 years, height 1.64+/-0.05 m, mass 77.36+/-13.34 kg)
participated in this study. Subjects performed a sit-to-stand movement from a
chair while position of center of pressure and knee angular speed were recorded.
Furthermore, maximal isokinetic knee extension and flexion strength at 60 degrees
/s, 120 degrees /s and 150 degrees /s was measured. Surface, electromyography
(EMG) from the biceps femoris (BF), vastus lateralis (VL) and vastus medialis
(VM) was recorded during all tests. Analysis of variance (ANOVA) showed that
during the sit-to-stand OA group demonstrated significantly lower knee angular
speed (44.49+/-9.61 degrees /s vs. 71.68+/-19.86 degrees /s), a more posterior
position of the center of pressure (39.20+/-7.02% vs. 41.95+/-2.49%) and a higher
antagonist BF activation (57.13+/-20.55% vs. 32.01+/-19.5%) compared with
controls (p<0.05). Further, women with knee OA demonstrated a lower Moment-to-EMG
ratio than controls in extension and eccentric flexion at 60 degrees /s and 150
degrees /s, while the opposite was found for concentric flexion at 60 degrees /s
(p<0.05). Among other factors, the slower performance of the sit-to-stand
movement in women with OA is due to a less efficient use of the knee extensor
muscles (less force per unit of EMG) and, perhaps, a higher BF antagonist
co-activation. This may lead subjects with OA to adopt a different movement
strategy compared with controls.
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Langue : ANGLAIS