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The activity pattern of the lumbo-pelvic muscles during prone hip extension in athletes with and without hamstring strain injury.

Authors: Emami M, Arab AM, Ghamkhar L

Patterns of altered muscular activation have been associated with musculoskeletal disorders. Previous studies have demonstrated muscle weakness or tightness in athletes who have sustained hamstring (HAM) injuries. To date, however, no study has clinically investigated the muscular activity pattern in subjects with HAM strain injuries. The purpose of this study was to investigate the activity pattern of the ipsilateral erector spinae (IES), contralateral erector spinae (CES), gluteus maximus (GM), and medial and lateral HAM muscles during the prone hip extension (PHE) test in athletes with and without history of HAM strain injury. Subjects performed three repetitions of the PHE and the electromyographic (EMG) outputs of the IES, CES, GM, and HAM muscles were recorded, processed and normalized to maximum voluntary electrical activity (MVE). Independent t-tests were used for comparing activation means of each muscle between athletes with and without history of HAM strain injury. The results of this study demonstrated significant differences in EMG activity of the GM (p= 0.04) and medial HAM (p = 0.01) between two groups. No significant difference was found in EMG signals of the IES (p= 0.26), CES (= 0.33) and lateral HAM (p= 0.58) between the two groups. Greater although non-significant normalized EMG outputs of IES, CES and lateral HAM were seen in athletes with history of HAM strain compared to those without HAM strain. Therefore, the findings of this study demonstrated greater normalized EMG activity of GM and medial HAM tested in athletes with history of HAM strain compared to those without HAM strain (altered activation pattern).

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