Occupational physical activity and the development of impaired mobility - The 12-year follow-up of the Baltimore epidemiologic catchment area sample

Objective: To examine the association between occupational physical activit y and self-reported disability. Design: Population-based case control analysis of a longitudinal population -based study in east Baltimore. Eligible participants were aged 18 to 29 yr in 1981, had complete information on occupation in 1981, no disability wit h tasks related to the domain of mobility in 1981, and complete information on mobility function in 1993 (n = 174). Occupations were divided into low, moderate, and high metabolic equivalents based on job category in 1981. Th e main outcome measure was disability defined by self-report of difficulty in one or more of five exercise mobility tasks in 1993. Results: Of 174 eligible participants, 45 (26%) reported the onset of disab ility at follow-up in 1993. A crude odds ratio of 0.25 (95% confidence inte rval, 0.06, 0.82) was found for the association of moderate compared with l ow occupational physical activity and the risk of incident disability in mo bility tasks. After adjustments to control for possible confounders, modera te job metabolic activity (1.8-2.9 Mets) was independently protective again st disability in this cohort (odds ratio = 0.25; 95% confidence interval = 0.083, 0.783). Conclusion: In this cohort of people aged 18 to 29 yr, a moderate amount of occupational physical activity was protective against disability in mobili ty tasks.