An electromyographic analysis of the hip abductors during load carriage: implications for hip joint protection.

Decreasing the relative force demands on the hip abductor muscles may reduce hip joint forces. The purpose of this study was to use surface electromyography (EMG) to determine the relative demand on the hip abductor muscles as subjects walked and carried single hand-held loads of multiple weights. Thirty healthy, college-aged subjects carried single hand-held loads by their side. The loads weighed between 3 and 30% of body weight. Loads were carried in a position either ipsilateral or contralateral to a given hip side. Normalized EMG (%EMG) was collected during the middle stance phase of walking. The amount of %EMG remained statistically equal to or less than the no-load EMG baseline for all ipsilateral-held loads and greater than the no-load EMG for all contralateral-held loads above 3% body weight. Load positions and weights that generated %EMG levels less than or equal to the no-load baseline most likely offer a degree of hip joint protection for persons with hip disability.