Domains of Physical Activity and All-cause Mortality: Systematic Review and Dose-response Meta-analysis of Cohort Studies

Background: The dose-response relation between physical activity and all-cause mortality is not well defined at present. We conducted a systematic review and meta-analysis to determine the association with all-cause mortality of different domains of physical activity and of defined increases in physical activity and energy expenditure.

Methods: MEDLINE, Embase and the Cochrane Library were searched up to September 2010 for cohort studies examining all-cause mortality across different domains and levels of physical activity in adult general populations. We estimated combined risk ratios (RRs) associated with defined increments and recommended levels, using random-effects meta-analysis and dose-response meta-regression models.

Results: Data from 80 studies with 1 338 143 participants (118 121 deaths) were included. Combined RRs comparing highest with lowest activity levels were 0.65 [95% confidence interval (95% CI) 0.60-0.71] for total activity, 0.74 (95% CI 0.70-0.77) for leisure activity, 0.64 (95% CI 0.55-0.75) for activities of daily living and 0.83 (95% CI 0.71-0.97) for occupational activity. RRs per 1-h increment per week were 0.91 (95% CI 0.87-0.94) for vigorous exercise and 0.96 (95% CI 0.93-0.98) for moderate-intensity activities of daily living. RRs corresponding to 150 and 300 min/week of moderate to vigorous activity were 0.86 (95% CI 0.80-0.92) and 0.74 (95% CI 0.65-0.85), respectively. Mortality reductions were more pronounced in women.

Conclusion: Higher levels of total and domain-specific physical activity were associated with reduced all-cause mortality. Risk reduction per unit of time increase was largest for vigorous exercise. Moderate-intensity activities of daily living were to a lesser extent beneficial in reducing mortality.