A comparison of motor control characteristics of the dominant and non-dominant arms in response to assistive force during unilateral task

BACKGROUND: In recent years, power assist suits have been used in nursing and rehabilitation scenarios. The external assistive force might disturb the user's motor control system during the process of assisted training using power assist suit, thus affect the progress of rehabilitation. With the consideration of the non-negligible physiological differences between upper limbs, this study focused on the physiological responses of the two arms against the external assistive force. OBJECTIVE: To investigate and contrast the impact of assistive force on dominant and non-dominant arms during unilateral isometric elbow flexion. METHODS: Participants were instructed to adjust force exertion to a target value based on the visual feedback. Task performances including muscle activity of agonist and antagonist muscles, force steadiness and rated perceived exertion were evaluated at multiple workload and assistive load conditions. RESULTS: No significant differences in muscle activity of agonist and antagonist muscles between the two arms. In contrast, the dominant arm showed a higher assist efficiency at a low assistive level, whereas the non-dominant arm had a lower level of force fluctuation during a unilateral force matching task. CONCLUSIONS: Both arms could utilize the assistive force to reduce muscle activity. However, the two arms showed different abilities in response to external assistive force. This indicates distinct motor control strategies for each arm and implicates the necessity of side-individualized rehabilitative approach for achieving a better training effect.