[Characteristics of vertical posture maintenance during standing with asymmetrical legs loading]

We studied the motion of the common center of pressure (CP) and of right and left foot CP, while maintaining a vertical posture when standing with symmetrical legs loading and with the transfer a part of weight to the right and left leg. It was shown that when standing with symmetrical legs loading the single leg CP motion occurred along a straight line with small side deviations in contrast to common CP motion, which was along an irregular curve, which often changed the direction and covered some area. When weight was transferred on one leg the motion of CP of loaded leg was similar to the motion of CP of that leg during standing with symmetrical load. The motion of CP of unloaded leg was along an irregular curve. During standing with weight transferred on one leg, the correlation between the CP movements of the left and right foot was reduced compared to standing with symmetrical load on thelegs. The velocity of loaded leg CP increased in the sagittal direction, but did not change inthe frontal direction. The velocity of unloaded leg CP motion did not change in the sagittal direction, and increased in the frontal. It was suggested that during standing with asymmetrical load on legs the involvement of the leg in maintaining the vertical posture depends on the load supported by this leg.