Leisure-Time and Occupational Physical Activity Associates Differently with Epigenetic Aging.
Level 3 - non-randomized controlled study
Cross-sectional twin study with quantitative genetic modeling
PubMed 32868581 · doi:10.1249/MSS.0000000000002498
What was done
Researchers evaluated the cross-sectional association between physical activity domains and blood DNA methylation (DNAm) age acceleration across three clocks: DNAm age, PhenoAge, and GrimAge. Participants were 285 young adult twin pairs (aged 21–25 yr) and 235 older twin pairs (aged 55–74 yr), including 16 pairs discordant for long-term leisure-time physical activity. Physical activity was assessed with sport, leisure-time, and work indices using the Baecke Questionnaire. Genetic and environmental variance components were estimated with quantitative genetic modeling.
What was found
Epigenetic age acceleration was approximately 60% heritable in both cohorts. In sex-adjusted models, higher sport index was associated with slower GrimAge acceleration, whereas occupational physical activity was associated with faster GrimAge acceleration. Genetic and nonshared environmental factors shared with sport index explained 1.5%–2.7% and 1.9%–3.5% of variance in GrimAge acceleration, respectively; for occupational activity, corresponding proportions were 0.4%–1.8% and 0.7%–1.8%. After adjusting for smoking status, all explained variance proportions fell below 0.5%.
Why it matters
This study provides biological evidence supporting the physical activity paradox—that occupational physical activity does not confer the same anti-aging profile as leisure exercise—while demonstrating that lifestyle confounders like smoking account for most of the apparent association.
Limits
The study is cross-sectional, preventing causal conclusions. Physical activity was self-reported via questionnaires rather than measured objectively. The discordant twin subsample was small (16 pairs), and the vast majority of observed variance explained by physical activity disappeared after controlling for smoking status.
Cited by
- contradicts Genetics is estimated to account for only about 10% to at most 20% of variation in epigenetic aging rates.