Muscle Activation of the Uninjured Leg During an Acute Achilles Tendon Rupture

Abstract

The purpose of this study was to describe muscle activation of the uninjured leg during an acute Achilles tendon rupture. Electromyographic (EMG) data were collected on the following muscles: medial hamstring, biceps femoris, gluteus medius, gluteus maximus, and the gastrocnemius while the participant was performing a round-off dismount type of maneuver in which she sustained an Achilles tendon rupture. Electromyographic data analysis suggested that the participant fell into a knee valgus flexed hip position on the uninjured leg immediately after the injury. Vastus medialis obliqueous activity indicated a position of knee valgus, whereas the shutdown of the gluteus medius and gluteus maximus indicated the patient's hip was falling into hip collapse. The lateral hamstring activity indicated an attempt to catch the falling pelvis and that the medial hamstrings were most likely caught in the reflex arc of the gluteals. If the decreased EMG activity in the uninjured limb occurred subsequently to the rupture, the resultant kinetic chain activity displays the way the body adapts because of a traumatic injury of the lower extremity. Reproduction of the muscular pattern of activity in landing maneuvers and subsequent training intervention may reveal targeting muscle groups that have been shown to fail early. Targeting the muscle groups through training interventions may have an impact on injury reduction patterns.