Effect of lower-extremity muscle fatigue on postural control

OBJECTIVE: To examine the effects of fatigue of the lower extremity on postural control during single-leg stance. DESIGN: Pretest-posttest. SETTING: University research laboratory. PARTICIPANTS: Fourteen healthy volunteers (age, 21+/-2y) with no history of lower-extremity injury or neurologic deficits. INTERVENTIONS: Testing consisted of isokinetically fatiguing the sagittal plane movers of the ankle, knee, or hip with measures of static postural control. Postural control was assessed with three 30-second trials during unilateral stance with eyes open. MAIN OUTCOME MEASURES: Center of pressure excursion velocity (COPV) in the frontal and sagittal planes. RESULTS: Fatigue at the knee and hip led to postural control impairment in the frontal plane, whereas fatigue at the ankle did not. In the sagittal plane, fatigue at all 3 joints contributed to postural control impairment. CONCLUSIONS: Our results suggest that there is an effect of localized fatigue of the sagittal plane movers of the lower extremity on COPV. It appears that fatigue about the hip and knee had a greater adverse affect on COPV.