Antigravity assistive force reduces muscle activations during shoulder elevation movements

We investigated the effect of a continuous upward force applied to the arm on shoulder neuromuscular activity and kinematics in healthy young adults. With assistance compared to without, muscle activity was lower in muscles contributing to shoulder elevation and unchanged in other muscles. The shoulder kinematics between assistance conditions differed during the first 40% of movement, but remained similar at higher elevation angles. Importantly, our results suggest that continuous passive assistance may help people with shoulder disability move more efficiently.