Modality of postural movement in men and women with both arms flexed during standing

We investigated postural movement associated with bilateral arm flexion in response to a light signal during standing in 179 healthy men and women to assess whether individual and sex differences arc evident in the postural movement pattern. The following results were obtained. (a) A correlation of -.87 was noted between movement angles of the foot-leg and leg-trunk. (b) Individual differences in movement angle were approximately twice as large in the hip joint as in the ankle and knee joints, and the movement angle of the leg trunk showed approximately half the number of extension as flexion movements. (c) The postural movement pattern was categorized on the basis of the movement angle of the foot leg and leg trunk into the following three patterns: hip flexion, backward leaning, and hip extension. The percentages of subjects showing these patterns were 59.2%, 33.5%, and 7.3%, respectively. (d) The inclination angle reflecting the righting response showed a gradual increase in size in the order of trunk, head, and neck. However, the righting response was not controlled precisely enough to enable subjects to maintain the inclination angle in a quiet standing posture. (e) We identified a significant sex difference in the relative frequency of subjects in the postural movement pattern.