EFFECT OF PLANTAR FLEXOR AND DORSIFLEXOR FATIGUE ON UNILATERAL POSTURAL CONTROL

The purpose of this study was to determine the effect of plantar flexo r and dorsiflexor fatigue on postural sway amplitude during unilateral , or one-legged, stance. It was hypothesized that plantar flexor and d orsiflexor fatigue would increase unilateral postural sway amplitude. Eight uninjured male subjects participated in pre- and postfatigue uni lateral stability tests. Selected parameters describing medial-lateral (ML) and anterior-posterior (AP) postural sway were measured on a Cha ttecx Balance System before and after an isokinetic fatigue protocol. The fatigue protocol resulted in a significant increase in ML postural sway amplitude (p < 0.05) and an increase in AP sway amplitude (p = 0 .065). Previously, links have been established between increased postu ral sway amplitude and ankle joint injury. Thus, fatigue of the planta r flexors and dorsiflexors, which increased postural sway amplitude, m ay render the ankle joint susceptible to injury. Induced ankle muscle fatigue may represent a valid paradigm to study the causes of traumati c ankle joint injury.