British Bobath Tutors Association

This study explored the effect of body asymmetry on anticipatory postural adjustments (APAs) in six healthy subjects between the ages of twenty two and twenty seven, without any known neurological or muscle disorders, performing a motor task. The subjects stood in a symmetrical stance as well as with their right or left lower limb externally rotated, a commonly observed alignment in individuals post stroke, in three experimental paradigms. Electromyography activity of the trunk and lower limb muscles were recorded during a self-induced perturbation and were quantified within the time intervals typical of APAs. The authors found that asymmetrical body positioning was associated with significant asymmetrical patterns of APAs. These APA asymmetries were dependent upon the side in which the body asymmetry was induced. Reduced APAs were observed in the asymmetrical lower limb muscles, while increased APAs were seen in the muscles on the contralateral side. Postural asymmetry can be due to intrinsic and extrinsic factors and can result in decreased loading and degenerative changes as well as postural instability. The authors conclude these findings stress the important role that body asymmetries play in the control of upright posture.