THE INFLUENCE OF ANKLE SPRAIN INJURY ON MUSCLE ACTIVATION DURING HIP EXTENSION

The likely influence of a localised injury in a distal joint on the fu nction of proximal muscles is an important consideration in assessment and treatment of musculoskeletal injuries. However, little experiment al evidence in humans exists in this area. Accordingly, a controlled s tudy was carried out, in which the function of muscles at the hip was compared between subjects who had suffered previous severe unilateral ankle sprain and matched control subjects. The pattern of activation o f the gluteus maximus, the hamstring muscles and the ipsilateral and c ontralateral erector spinae muscles was monitored through the use of s urface electromyography during hip extension from prone lying. Analyse s revealed that the pattern of muscle activation in subjects with prev ious injury differed markedly from normal control subjects, and that c hanges appeared to occur on both the uninjured and the injured sides o f the body. A significant difference between the two groups was the de lay in onset of activation of the gluteus maximus in previously injure d subjects. The existence of remote changes in muscle function followi ng injury found in this study emphasise the importance of extending as sessment beyond the side and site of injury.