Do ankle foot orthoses modify postural control during bipedal quiet standing following a localized fatigue of the ankle muscles?

The purpose of the present experiment was to investigate the effects of wearing ankle foot orthoses (AFO) on postural control during bipedal quiet standing following a localized fatigue of the ankle muscles. To this aim, eight young healthy subjects were asked to stand upright as immobile as possible with and without AFO in two conditions of non-fatigue and fatigue of the ankle muscles. The center of foot pressure displacements (CoP) were recorded using a force platform. Larger CoP displacements in the fatigue than non-fatigue condition were observed without AFO along both the medio-lateral and antero-posterior axes. Interestingly, with AFO, these destabilizing effects were not observed along the medio-lateral axis. Altogether, the present findings suggested that the AFO allowed the subjects to limit the postural perturbation induced by a localized fatigue of the ankle muscles during bipedal quiet standing.