Objective: To investigate the association between physical activity (eg, energy expenditure) and survival over 11 years of follow-up in a large representative community sample of older Brazilian adults with a low level of education. Furthermore, we assessed sex as a potential effect modifier of this association.
Materials and methods: A population-based prospective cohort study was conducted on all the ≥60-year-old residents in Bambuí city (Brazil). A total of 1,606 subjects (92.2% of the population) enrolled, and 1,378 (85.8%) were included in this study. Type, frequency, and duration of physical activity were assessed in the baseline survey questionnaire, and the metabolic equivalent task tertiles were estimated. The follow-up time was 11 years (1997-2007), and the end point was mortality. Deaths were reported by next of kin during the annual follow-up interview and ascertained through the Brazilian System of Information on Mortality, Brazilian Ministry of Health. Hazard ratios (95% confidence intervals [CIs]) were estimated by Cox proportional-hazard models, and potential confounders were considered.
Results: A statistically significant interaction (P<0.03) was found between sex and energy expenditure. Among older men, increases in levels of physical activity were associated with reduced mortality risk. The hazard ratios were 0.59 (95% CI 0.43-0.81) and 0.47 (95% CI 0.34-0.66) for the second and third tertiles, respectively. Among older women, there was no significant association between physical activity and mortality.
Conclusion: It was possible to observe the effect of physical activity in reducing mortality risk, and there was a significant interaction between sex and energy expenditure, which should be considered in the analysis of this association in different populations.
Keywords: elderly; mortality; physical activity; sex.