Analysis of the ratios of medial-lateral and proximal-distal muscle activities surrounding the hip joint in the step-up and step-down positions.

Abstract

Many practitioners recommend step-up and step-down exercises to increase muscle strength in the lower extremities. However, decreased stability of the hip joint and imbalanced muscle activities can alter limb biomechanics during these movements. This study investigated muscle imbalance between the medial and lateral muscle components and between the proximal and distal muscle components by expressing the proportions of muscle activation in the step-up and step-down positions. Nineteen subjects participated in the study. Activity of the vastus medialis oblique, vastus lateralis, semitendinosus, biceps femoris, adductor, gluteus medius, and gluteus maximus was assessed. The semitendinosus-biceps femoris ratio was higher in the step-down position than in the step-up position. The adductor-gluteus medius, adductor-vastus lateralis, and adductor-biceps ratios were higher in the step-up position than in the step-down position. The gluteus maximus-biceps ratio was greater in the step-down position than in the step-up position. In the hip joint, internal rotation was significantly greater in the step-up position. The transverse angle of the hip joint has a greater effect on the medial-lateral balance of the muscles surrounding the hip joint. Muscle activation in the medial hamstring is greater in the step-down position; in the adductor, muscle activation is greater in the step-up position. The step-down position is more appropriate for those with proximal weakness, as it can promote muscle activation in the gluteus maximus while maintaining biceps femoris activation.