The Impact of Segmental Trunk Support on Posture and Reaching While Sitting in Healthy Adults

ABSTRACT

The authors investigated postural and arm control in seated reaches while providing trunk support at midribs and pelvic levels in adults. Kinematics and electromyography of the arm and ipsiliateral and contralateral paraspinal muscles were examined before and during reaching. Kinematics remained constant across conditions, but changes were observed in neuromuscular control. With midribs support, the ipsilateral cervical muscle showed either increased anticipatory activity or earlier compensatory muscle responses, suggesting its major role in head stabilization. The baseline activity of bilateral lumbar muscles was enhanced with midribs support, whereas with pelvic support, the activation frequency of paraspinal muscles increased during reaching. The results suggest that segmental trunk support in healthy adults modulates ipsilateral or contralateral paraspinal activity while overall kinematic outputs remain invariant.

Keywords:

• EMG
• goal-directed action
• kinematics
• postural control

Additional information

Funding

This research was funded by the National Institute of Health Grant 1R01HD062745-01 (Dr. Marjorie H. Woollacott, principal investigator).