The relationship between muscle activity of the quadriceps muscle and ground reaction force in the supporting leg during ascent and descent motions

Abstract

Purpose: To understand stair ascent and descent motions, we examined the muscle activities of the vastus medialis (VM) and vastus lateralis (VL) and the ground reaction force (GRF) in the supporting leg of eight young healthy males. We also compared these data with level walking data. Result: The muscle activities of VM and VL during the ascent motion were the highest among the three tasks. The muscle activity ratios of VM and VL during ascending and descending differed from that during level walking. The VM contribution increased in the ascent and descent tasks compared with level walking. There was no significant difference for the vertical GRF among the tasks. Although the anterior-posterior GRF during the ascent motion was similar to that during level walking, the anterior-posterior GRF during the descent motion was different from that of the ascent motion and level walking. Further, the medial-lateral GRF during ascending and descending were different from that during level walking. Conclusion: The results of this study suggest that the increased VM contribution of the supporting leg may be related to the change of medial-lateral GRF during ascent and descent. This finding will add knowledge to the rehabilitation and physical therapy of ascent and descent motions for elderly people and patients with motor disorders.