Landing is a frequently executed motion in athletic activities, and injuries have been reported to occur often during landing, suggesting that legs are subjected to large loads during landing. Many studies, based on posture and floor reaction, have been conducted on this subject; however, few have been conducted from the muscular-activity perspective. Moreover, we found no studies investigating the functions of biarticular muscles (muscles that cross two joints). Therefore, we studied landing motion in which feet make ground contact after falling from a suspended position. Our objective was to clarify activity patterns of biarticular thigh muscles in two different trunk postures. Our results showed that the activity patterns of the antagonistic biarticular muscle pair at the thigh anterior and posterior were affected by trunk posture.

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