Electronic Thesis and Dissertation Repository


Master of Science




James P Dickey


Increased quadratus lumborum activation and decreased gluteal activation may lead to lateral pelvic drop and increased hip adduction and internal rotation during single-leg exercises. These activation patterns and motions are associated with low back pain or lower extremity injuries. The purpose of this study was to evaluate if mechanically restricting hip adduction and internal rotation of the femur affected muscle activation. Twenty female track and field athletes performed single-leg squats and step-ups, and the quadratus lumborum, gluteus medius and maximus muscles activations were measured with surface electromyography. This study tested the hypothesis that mechanically restricted exercises would decrease quadratus lumborum and increase gluteal muscle activation. Mechanically restricted single-leg squats performed on the left side significantly decreased ipsilateral quadratus lumborum muscle activation. Athletes should focus on maintaining lower extremity alignment in the frontal plane to decrease quadratus lumborum activation. There was some evidence that these athletes have asymmetrical muscle activation patterns.