Predictors of physical disability after age 50. Six-year longitudinal study in a runners club and a university population.

Predictors of disability were studied over 6 years among 50- to 80-year-old members of a runners club (N = 407) and a university population (N = 299). Data have been collected annually since 1984 on sociodemographic characteristics, health habits, medical history, medication use, family history, psychological parameters, and physical disability as measured by the Health Assessment Questionnaire. Members of the runners club, compared to university participants, had better overall health and less disability at baseline (0.03 versus 0.08) and at 6-year follow-up (0.04 versus 0.24). Predictors of greater subsequent disability among university participants were greater baseline disability, greater medication use, greater number of pack-years of cigarette smoking, older age, being unmarried, higher blood pressure, history of arthritis, and less physical activity compared to one's peers. In addition, changes in characteristics during follow-up that were independently associated with greater disability were development of joint pain, arthritis, or bone fracture and increased body mass index. Predictors of greater disability in the runners group included greater baseline disability, being a nonrunner at baseline, greater dietary salt intake, more years of running at baseline, and greater frequency of physician visits for running injuries. Greater disability in this group also was associated with increases in medication use, declining alcohol consumption, and development of joint pain over 6 years. Results of this study suggest that physical disability is linked to a constellation of characteristics, health habits, medical history, comorbidities, and marital status. While self-selection bias cannot be ruled out entirely, these data are consistent with the hypothesis that those who engage in high levels of physical activity beyond middle age will continue to maintain better functional abilities.