Physical activity and mortality risk in the Japanese elderly: a cohort study.

Background: Physical activity recommendations for older adults with poor health needs to be understood.

Purpose: This study aims to examine the association between the frequency of physical activity and mortality among a sample of elderly subjects, most of whom were under treatment for pre-existing disease.

Methods: Data on the frequency of leisure-time physical activity, walking for transportation, and non-exercise physical activity were obtained from a population-based cohort study in Shizuoka, Japan. Of the randomly selected 22,200 residents aged 65-84 years, 10,385 subjects were followed from 1999 to 2006 and analyzed. Hazard ratios (HRs) and 95% CIs were obtained for all-cause; cardiovascular disease (CVD); and cancer mortality, after adjusting for covariates such as pre-existing disease(s). A subgroup analysis that was restricted to subjects under treatment for pre-existing disease(s) at baseline was further conducted. Data were collected between 1999 and 2006, and all analyses were conducted in 2008 and 2009.

Results: Every physical activity was associated with a reduced risk of all-cause and CVD mortality, among not only the total sample but even those under treatment. The HRs for CVD mortality among participants with 5 or more days of non-exercise physical activity per week for the total sample and those with pre-existing disease(s) were 0.38 (95% CI=0.22, 0.55) and 0.35 (95% CI=0.24, 0.52), respectively, compared with no non-exercise physical activity. The association between physical activity and cancer mortality was not clear.

Conclusions: This study suggests a protective effect of physical activity on all-cause and CVD mortality among Japanese elderly people with pre-existing disease.