Effects of isokinetic ankle fatigue on the maintenance of balance and postural limits

Abstract

Objective: To quantify changes in balance parameters and ranges of postural control at the ankle after isokinetic fatigue.

Design: Before-after trials, with a 5 x 6 repeated-measures design.

Setting: General community.

Participants: Twenty-four men (age, 24.9 +/- 3.92y; height, 177.79 +/- 6.36cm; weight, 80.78 +/- 13.22kg) without ankle trauma within 2 years.

Interventions: Fatigue of the plantarflexors and dorsiflexors was induced by isokinetic contractions. Balance was assessed by using a unilateral test (15-s quiet stance, 10-s lean test) on a force platform immediately before and at 0 (T0), 10 (T10), 20 (T20), and 30 (T30) minutes postfatigue.

Main outcome measure: Mediolateral (ML) and fore-aft (FA) sway as well as ML and FA displacement were analyzed by analysis of variance with repeated measures for time (alpha =.05).

Results: In quiet stance, ML sway was greater at T0, whereas total sway increased at all time points postfatigue (P < .05). For the lean test, FA sway increased at T0 and T10, and total sway increased at all time points (P < .05). Both ML and FA displacement significantly differed at T0 (P < .05). All sway parameters returned to baseline within 20 minutes.

Conclusions: Isokinetic fatigue of ankle plantarflexors and dorsiflexors significantly influences sway parameters and ranges of postural control in healthy young men. These perturbations are transient, and recovery occurs within 20 minutes.