Degraded postural performance after muscle fatigue can be compensated by skin stimulation

It has been shown that the ability of humans to maintain a quiet standing posture is degraded after fatigue of the muscles at the ankle. Yet, it has also been shown that skin stimulation at the ankle could improve postural performance. In the present study, we addressed the issue of the interaction of these two effects. Subjects were tested with the eyes closed in four conditions of quiet stance: with or without skin stimulation and before and after a fatigue protocol. The skin was stimulated with a piece of medical adhesive tape on the Achilles' tendon. The fatigue protocol consisted of multiple sets of ankle plantar flexion of both legs on stool. Without fatigue, we did not observe a significant effect of the tape. With fatigue, subjects decreased their postural performance significantly, but this effect was cancelled out when a piece of tape was glued on the Achilles' tendon. This indicated that the beneficial effect of the tape was unveiled by the degraded postural performance after fatigue. We conclude that, when the muscular sensory input flow normally relevant for the postural system is impaired due to fatigue, the weight of cutaneous information increases for the successful representation of movements in space to adjust postural control.