The Effect of Fatigued Hip Abductors on Single-Leg Stance Postural Control and Muscle Control

Abstract

[Purpose] The purpose of this study was to clarify postural control and muscle activity of the gluteus medius and musculus erector spinae in a single-leg stance before and after hip muscle abductor fatigue.[Subjects] Subjects were 22 healthy male adults (mean age; 21.4 yrs) with no significant medical history or current medical problems.[Methods] We examined postural control and muscle activity in a single-leg standing position before and after hip muscle abductor fatigue. A statistical analysis was performed using the paired t-test before and after muscle fatigue, and Pearson's rank correlation coefficient was obtained for muscle activity associated with postural control.[Results] The results indicate a significant increase in stability indices, a decrease in gluteus medius muscle activity, and an increase in right musculus erector spinae activity after fatigue. There was a positive correlation between the increase in right musculus erector spinae activity and increase in postural control. [Conclusion] We believe that postural control increased in the orientation related to the working of the muscles due to their fatigue, and that muscle activity increased to compensate.

Effects of Intensive Up-to-Exhaustion Walking Exercise on the Center of Gravity Sway

“…These studies suggest that intensive walking exercises cause muscle fatigue in the whole body and legs and affect the COGS. On the other hand, Matsuda et al [9] reported that, although the X-axis trajectory length was affected by the hip abduction muscle fatigue, the Y-axis trajectory length remained unchanged. Here, both before/after (COP displacement in anterior-posterior; COP-AP) and left/right (medial-lateral; COP-ML) directions were affected, similarly to the data obtained during a walking exercise on a treadmill by Selthafner et al [15].…”

“…The balance function and leg strength are also involved in maintaining a stable posture [7]. During aging, the COGS is affected by the decline of nervous functions [8] and decreased leg strength [9].…”

“…Moreover, Selthafner et al [15] evidenced that walking on a treadmill (2 km/h) resulted in fluctuations of the center of pressure measured before and after the ex-ercise in the anteroposterior (COP displacement in anterior-posterior; COP-AP) and left-right (mediolateral; COP-ML) directions. Matsuda et al [9] compared the COGS measured before and after fatigue of the hip abductor muscles and showed that the left-right fluctuation (the X-axis trajectory length) was greater after muscular fatigue, whereas the before/after fluctuation (the Y-axis trajectory length) was not different. Pedaling is a leg-based exercise which the body weight is not carried by the legs, whereas walking is a whole body exercise, which imposes the body weight on the legs and uses arm movements.…”