Abstract
Life expectancy is increasing worldwide, with older adults expected to account for 16% of the population within 30 years. Understanding age-related declines in muscle function is crucial for prevention and maintaining independence in Activities of Daily Living (ADL). Additionally, a major consequence of these declines is the development of the physical frailty phenotype. Therefore, this study aimed to identify changes in muscular coordination during elbow flexion and extension with aging and varying movement velocities. Twelve older adults (76 ± 6.5 years) performed the movements at varying angular velocities using a constant 1 kg external load (0.4 Nm). Elbow joint kinematics and muscle activity (biceps brachii, brachioradialis, and triceps brachii) were recorded using motion capture and surface electromyography and compared to 15 healthy young adults (26.2 ± 3.2 years) under identical conditions. Clinical assessments in the older group also evaluated comorbidities, ADL dependency, and frailty risk. Despite being considered healthy, older adults showed indicators of physical decline and exhibited increased muscular coactivation, possibly as a compensatory mechanism to maintain joint stability. However, coordination patterns remained unchanged across velocities, indicating stability with age. These findings suggest changes may occur before clinical decline and should be considered in training strategies for older adults.