Article

There is growing evidence that aging and muscle fatigue result in impaired
postural reflexes in humans. Therefore, the objective of this study was to
examine the effects of ankle fatigue on functional reflex activity (FRA) during
gait perturbations in young and elderly men. Twenty-eight young (27.0+/-3.1
years, n=14) and old (67.2+/-3.7 years, n=14) healthy active men participated in
this study. Fatigue of the plantarflexors and dorsiflexors was induced by
isokinetic contractions. Pre and post-fatigue, subjects were tested for their
ability to compensate for decelerating gait perturbations while walking on a
treadmill. Latency, FRA of lower extremity muscles and angular velocity of the
ankle joint complex were analysed by means of surface electromyography and
goniometry. After the fatigue protocol, no significant main and interaction
effects were detected for the parameter latency in m. tibialis anterior (TA). For
both groups, a significant pre to post-test decrease in FRA in TA (p<.001) was
observed coming along with increases in antagonist coactivity (p=.013) and
maximal angular velocity of the ankle joint (p=.007). However, no significant
groupxtest interactions were found for the three parameters. Ankle fatigue has an
impact on the ability to compensate for gait perturbations in young and elderly
adults. However, no significant differences in all analysed parameters were
detected between young and elderly subjects. These results may imply that
age-related deteriorations in the postural control system do not specifically
affect the ability to compensate for gait perturbations under fatigued condition.
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Langue : ANGLAIS