G1-1　Comparison of muscle adaptation toward assistive force between the young and elderly.

Abstract

Improving our understanding of muscle response towards assistive force is important not only to ensure the effectiveness of assistive devices but also to avoid injury due to excessive assistance. Therefore, the objective of this study was to compare muscle activities towards assistive force during isometric elbow flexion in young and elderly participants. The study involved right-handed young (n = 9, 25.3 ± 2.4 years) and elderly (n = 9, 68.4 ± 3.3 years) male participants and determined the maximum voluntary contraction (MVC) and maximum workload for each participant. The participants performed isometric elbow flexion under two conditions of submaximal workload (20% and 40%) and three levels of assistive force (0%, 50%, and 100%). The electromyographic activity of agonist and antagonist muscles decreased with increased levels of assistive force under both workload conditions in both groups. In addition, a more effective reduction in electromyographic activity was observed during 50% assistance in both muscles for both groups. In summary, assistive force relieved the exertion in the agonist muscle in both young and elderly groups; however, their effects were influenced by the level of assistive force.