Affiliations: [a] Department of Physical Therapy, Youngsan University, Yangsan, Korea | [b] Rehabilitation Medicine Device Research Institute, G.O. Meditech, Korea | [c] Department of Physical Therapy, Kyungsung University, Busan, Korea
Correspondence:
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Corresponding author: So Hyun Park, Department of Physical Therapy, Youngsan University, Yangsan, Korea. E-mail: ptpsh@ysu.ac.kr.
Abstract: BACKGROUND: 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. OBJECTIVE: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.
Keywords: Hip joint, muscle activities, step-up, step-down
