Article

Although the effect of muscle fatigue on posture is apparent, results are
inconsistent across studies and this may be due to differences in the fatigue
protocol, postural stance used and/or amount of visual information provided. The
purpose of this study was to test the hypothesis that fatigue would have a more
pronounced effect for more difficult compared with less difficult postural tasks.
Twenty-three young adults (mean age 22 +/- 3 years) were asked to perform three
different postural tasks on a force-platform: feet together, semi-tandem and
single-leg stance, before and immediately after fatiguing the plantarflexor
muscles. Three 30-s trials were performed for each postural task with eyes open
and eyes closed. The fatigue protocol consisted of an isometric contraction of
the plantarflexor muscles, with subjects instructed to rise on their toes and
maintain this position until exhaustion. The 95% ellipse area of the center of
pressure (COP), as well as the COP sway amplitudes (standard deviation) and sway
velocities in the antero-posterior and medio-lateral directions were calculated.
All variables were greater for each postural task performed without vision
compared to with vision, with the greatest difference found during the single-leg
task. For both visual conditions, all variables increased as the difficulty of
the task increased. Fatigue of the plantarflexor muscles mostly affected postural
sway variables during single-leg and feet together tasks. In conclusion, the
reduction in postural stability with muscle fatigue of the plantarflexors does
not depend on the difficulty of the postural task.
CI - Copyright (c) 2010 Elsevier B.V. All rights reserved.

Langue : ANGLAIS