Leisure time physical activity of moderate to vigorous intensity and mortality: a large pooled cohort analysis.
Level 3 - non-randomized controlled study
Pooled analysis of prospective non-randomized cohort studies.
PubMed 23139642 · doi:10.1371/journal.pmed.1001335
What was done
Analyzed pooled data from six prospective cohort studies in the National Cancer Institute Cohort Consortium, tracking 654,827 individuals aged 21-90 years over a median of 10 years with 82,465 deaths. Leisure time physical activity was categorized by metabolic equivalent hours per week (MET-h/wk). Life expectancies and years of life gained or lost after age 40 were estimated using direct adjusted survival curves with bootstrap 95% confidence intervals across activity levels and body mass index categories.
What was found
Low physical activity (0.1-3.74 MET-h/wk, equivalent to brisk walking up to 75 min/wk) was associated with a 1.8-year gain in life expectancy (95% CI: 1.6-2.0) relative to no leisure time activity. The highest activity level (22.5+ MET-h/wk, equivalent to 450+ min/wk of brisk walking) was associated with a 4.5-year gain (95% CI: 4.3-4.7). Life expectancy gains were observed across every BMI category. In joint analysis, individuals who were active (7.5+ MET-h/wk) and normal weight (BMI 18.5-24.9) gained 7.2 years of life (95% CI: 6.5-7.9) compared to those who were inactive (0 MET-h/wk) and obese (BMI 35.0+).
Why it matters
This paper quantifies the survival benefit of physical activity directly in years of life gained, showing that even modest amounts below standard recommendations confer substantial longevity benefits across all weight classes.
Limits
Physical activity and body mass index were measured via self-report rather than objective assessment. The observational cohort design cannot rule out residual confounding or reverse causation.
Cited by
- contradicts A study in obese individuals found approximately an 8-year difference in lifespan between sedentary obese individuals and moderately exercising obese individuals.