立位における膝関節屈曲運動に伴う筋活動および関節音

抄録

  We investigated muscle activity and the joint sounds associated with knee flexion in standing. Thirteen healthy young adults were asked to flex their knee to 45° once per second for 5 repetitions from a quiet standing posture. Joint angle, anterior movement and joint sounds of the knee, and muscle activity of the rectus femoris (RF), biceps femoris (BF), and gastrocnemius medialis (GcM) were measured. Only GcM activity started approximately 50 ms prior to the onset of knee flexion, which suggests that GcM could be strongly related to the release of knee locking. RF activity peaked about 60 ms after RF onset (first RF peak). Approximately 50 ms after the first RF peak, the first joint sound was observed along with acceleration peaks in joint angle and anterior movement of the knee. This finding suggests that the first joint sound could be related to higher RF tension and/or friction caused by the quick sliding of the femur on the tibia. The RF peak was followed by low activity for about 60 ms, before switching to an increase in activity to reach a second RF peak. Approximately 50 ms after the second peak, a second joint sound was observed. This suggests that the second joint sound is associated with higher RF tension to resist the fall of the center of gravity, which leads by a stretch reflex of the RF.