  Whereas the acuity of the position sense at the ankle can be disturbed by
muscle fatigue, it recently also has been shown to be improved, under normal
ankle neuromuscular state, through the use of an artificial tongue-placed
tactile biofeedback. The underlying principle of this biofeedback consisted of
supplying individuals with supplementary information about the position of
their matching ankle position relative to their reference ankle position
through electrotactile stimulation of the tongue. Within this context, the
purpose of the present experiment was to investigate whether this biofeedback
could mitigate the deleterious effect of muscle fatigue on joint position sense
at the ankle. To address this objective, sixteen young healthy university
students were asked to perform an active ankle-matching task in two conditions
of No-fatigue and Fatigue of the ankle muscles and two conditions of
No-biofeedback and Biofeedback. Measures of the overall accuracy and the
variability of the positioning were determined using the absolute error and the
variable error, respectively. Results showed that the availability of the
biofeedback allowed the subjects to suppress the deleterious effects of muscle
fatigue on joint position sense at the ankle. In the context of sensory
re-weighting process, these findings suggested that the central nervous system
was able to integrate and increase the relative contribution of the artificial
tongue-placed tactile biofeedback to compensate for a proprioceptive
degradation at the ankle.
