Recent Physical Activity in Relation to DNA Damage and Repair Using the Comet Assay

Background: Limited evidence suggests that very high-intensity exercise is positively associated with DNA damage but moderate exercise may be associated with DNA repair. Methods: Participants were 220 healthy, Washington State 50- to 76-year-olds in the validity/biomarker substudy of the VITamins And Lifestyle (VITAL) cohort, who provided blood samples and completed questionnaires assessing recent physical activity and demographic and health factors. Measures included nested activity subsets: total activity, moderate- plus high-intensity activity, and high-intensity activity. DNA damage (n = 122) and repair (n = 99) were measured using the comet assay. Multivariate linear regression was used to estimate regression coefficients and associated 95% confidence intervals (CIs) for relationships between MET-hours per week of activity and each DNA outcome (damage, and 15- and 60-minute repair capacities). Results: DNA damage was not associated with any measure of activity. However, 60-minute DNA repair was positively associated with both total activity (beta = 0.21, 95% CI: 0.0057-0.412; P = .044) and high-intensity activity (beta = 0.31, 95% CI: 0.20-0.60; P = .036), adjusting for age, sex, BMI, and current multivitamin use. Conclusions: This study is the first to assess broad ranges of activity intensity levels related to DNA damage and repair. Physical activity was unrelated to DNA damage but was associated with increased repair.