Effects of Repetitive Reaching Movements on Performance and Postural Control

Abstract

Abstract.[Purpose] The purpose of this study was to examine whether muscle activity and joint movement in the lower limbs related to postural control are affected by repetitive reaching movements.[Methods] Fourteen healthy subjects attempted to reach a small target as fast as possible while standing. The target was placed at approximately the maximum reach distance. The reaching movement was repeated 50 times. Positions of each body segment were measured by three-dimensional motion analysis. Surface electromyograms (EMG) of tibialis anterior (TA) and gastrocnemius (GAS) were recorded. Parameters related to reaching performance and postural control were analyzed.[Results] With repetition of reaching movements, movement time and peak reaching velocity related to performance significantly increased. In addition, the onset of the EMG activity of TA appeared earlier, the integrated EMG activity of TA and GAS increased, and the maximum ankle dorsiflexion angle increased significantly. Changes in postural response were correlated with those of reaching performance. Moreover, postural response changed earlier than reaching performance.[Conclusion] Changes in postural control were induced by repeated reaching movements. These results suggest that changes in postural control associated with the central nervous system occur in advance in order to improve reaching performance.

Therapeutic effects of reaching with forward bending of trunk on postural stability, dynamic balance, and gait in individuals with chronic hemiparetic stroke

“…The movement of reaching out an arm towards a target varying in distance and direction during the performance of everyday tasks requires adaptation of postural changes through the action of the nervous and musculoskeletal systems in order to maintain a stable dynamic posture 12 , 13 , 14 ) . Voluntary movement of the upper limb when sitting or standing provides stability to the center of the trunk 26 ) .…”

“…This can promote postural movements in stroke patients according to the position of the target to be reached and the distance and direction, and so it is assumed to improve the ability to solve daily postural difficulties 11 ) . In stroke patients, performing external tasks, such as reaching for a target while considering direction and distance, promotes sensory and motor performance, and by finding ways to adapt to changes in posture, these exercises can improve posture and prevent falling 12 , 13 , 14 ) .…”

“…Several researchers have studied the effect of target distance (near vs. far in the sagittal plane) when performing the action of bending forwards and extending the arms in postural activities 14 , 15 , 16 ) . Functional movements, such as moving the torso while extending the arms, require movements of the trunk 17 ) , so they can help to develop the trunk muscles in hemiparesis patients 18 , 19 ) , while actions that require extending the arms to touch external targets in different directions and distances have been found to improve sensory processes and adaptation to postural changes 12 , 13 , 14 ) .…”