The effects of knee and ankle muscles surrounding the knee and ankle joints on one-leg static standing balance

The purpose of this study was to determine whether knee and ankle muscle fatigue affect one-leg static standing balance. We compared the affects of muscle fatigue between the knee and ankle joints on one-leg static standing balance. Sixty-four healthy subjects were used for this study: 44 men and 20 women, with an average age of 19.5. One leg static standing balance was measured at pre-fatigue and post-fatigue status by an instrumented balance assessment system (Kinesthetic Ability Training Balance Platform) which is commercially available for testing and balance training. Isokinetic exercises performed at 180 degree/sec on the Cybex 1200 were used to induce muscle fatigue. One-leg static standing balance ability was significantly decreased after knee and ankle muscle fatigue. There was a significantly greater decrease in one-leg static standing balance ability in ankle joint muscle fatigue as opposed to the knee joint muscles. Although these phenomena were not clearly understood, these results have important implications for rehabilitation of fatigable patients. These results suggest that excessive fatigue during rehabilitation may increase risk of reinjury and falling due to balance disturbance in patients with diseases involving fatigue. Further studies are required to determine the physiological mechanisms of muscle fatigue that play a role in decreasing one-leg static standing balance.