Article

The effect of muscle fatigue on quiet standing is equivocal, including its
duration/recovery and whether it leads to an increase in attentional demands. The
purpose of this study was to assess the effects of ankle and hip muscle fatigue
on postural sway and simple reaction time during a unipedal task. Two groups of
14 young adults (mean age=22.50+/-3.23) had to stand on their dominant leg for
30-s trials before and after fatigue of hip or ankle flexors and extensors. Half
of the unipedal trials were performed in a dual-task condition where subjects, in
addition to standing, had to respond verbally to an auditory stimulus. Sway area,
and sway variability and velocity in the AP and ML planes were calculated using
center of pressure data obtained from a force platform. Voice reaction time was
recorded seated and during the dual-task condition to assess attentional demands.
A main effect of fatigue was found for AP sway variability (p=0.027), AP sway
velocity (p=0.017) and ML sway velocity (p=0.004). Both groups showed increased
sway velocity in both directions and in reaction time during the dual-task
condition (p<0.001), but reaction time did not increase with fatigue. A group by
fatigue interaction was found significant for ML sway velocity (p=0.043). Results
suggest that hip and ankle fatigue affected postural control in the fatigued
plane (AP) but only hip fatigue affected postural control in the non-fatigued
plane (ML sway velocity). However, fatigue did not lead to an increase in
attentional demands and increased AP and ML sway velocity had recovered within
30min.
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Langue : ANGLAIS