Article

There is substantial evidence indicating an increase in the incidence of
lower limb joint osteoarthritis with increasing age. One factor that may
contribute to this is an age related reduction in the ability to attenuate the
impulse generated during gait and step descent. SCOPE: The aim of this study was
to investigate the differences between older and younger adults, in the
strategies used to attenuate the force generated between initial contact (IC) and
maximum vertical ground reaction force (vGRF) (impulse phase) when descending a
step. METHODS: Ten older participants aged 60-80 years (mean 65.3, SD +/-5) and
10 younger participants aged 20-30 years (mean 22.8, SD +/-2.5) took part in the
study. Vertical ground reaction force (vGRF) and the time taken to reach maximum
vGRF were measured. The maximum joint range of motion of the hip and knee during
step descent was measured between IC and the maximum vGRF. Electromyography (EMG)
was measured from four lower limb muscles and normalised to task for each
individual. RESULTS: There was a statistically significant difference between
older and younger adults in the amount of knee flexion and vastus lateralis EMG
activity in the leading leg during the impulse phase of step descent. Older
adults had less knee flexion (F(1,18)=5.48; p=0.031) and more vastus lateralis
EMG activity (F(1,18)=5.21; p=0.035) during step descent than younger adults.
CONCLUSION: Older and younger adults used different strategies during step
descent. Older adults demonstrated two strategies that have the potential to
increase the impulse of a step.
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Langue : ANGLAIS