Fig. 3: Theoretical relation between musculoskeletal fitness and independent living across a person's lifespan. As a person ages, his or her musculoskeletal fitness (i.e., muscular strength, muscular endurance, muscular power or flexibility) declines, such that a small impairment may result in disability. Many elderly people currently live near or below the functional threshold for dependence. High levels of (or improvements in) musculoskeletal fitness will enhance the capacity to meet the demands of everyday life and allow a person to maintain functional independence for a greater period.^9,10