Abstract
[Purpose] To examine the relationship between the pattern of contralateral lower-limb muscle activity and postural changes during lateral weight shift on the lower limb. [Subjects and Methods] Ten limbs of 10 healthy males were involved. During lateral weight shift in a standing position, movements were filmed using a video-recorder, contralateral lower limb muscle activity was evaluated using electromyography, and the center of foot pressure was measured. [Results] On the initiation of lateral weight shift, the leg-heel angle of the contralateral lower limb remained unchanged in 7 participants, and movements in the direction of inversion were observed among 3 participants. The muscle activity levels of peroneal, triceps surae, and foot inverter increased in the former, while those of peroneal and triceps surae increased after a rise in that of foot inverter in the latter. In all cases, the activity of the middle fibers of the gluteus medius was promoted. [Conclusion] Different foot movements and muscle activity patterns were also observed among healthy participants immediately after the initiation of lateral weight shift in a standing position, emphasizing the necessity of carefully assessing contralateral lower limbs during lateral weight shift in clinical environments.
