Age-related differences in muscle strength alter the feasible torque space of the shoulder in a musculoskeletal model

The prevalence of shoulder pathology increases with age, but the progressive changes driving this pathology remain unknown. Identifying the changes preceding symptom onset may permit early detection and prevention of pathology. Altered strength and coordination are thought to contribute to tissue degeneration, but changes in these factors have not been confirmed to precede pathology in humans. The feasible torque space, a measure of strength in all directions, is sensitive to both muscle strength and coordination and may therefore be able to detect age-related changes in these factors. Our objective was to quantify the impact of simulated age-related changes in muscle strength on the feasible torque space of the shoulder in a musculoskeletal model. We found a significant difference in the feasible torque space of the shoulder between a younger and older-adult model, demonstrating the potential utility of these metrics for detecting age-related changes in shoulder strength.