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 50–76 year-olds in the validity/biomarker sub-study 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 (β=0.21, 95% CI: 0.0057, 0.412; p=0.044) and high-intensity activity (β=0.31, 95% CI: 0.20, 0.60; p=0.036), 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.

Purpose Obesity is associated with impaired quality of life (QoL), but less is known about physical activity. We investigated how decreases in body mass index (BMI) and increases in activity affect obesity-specific QoL and potential gender differences in associations. Methods In a large worksite-randomized trial of a multilevel intervention on diet and physical activity behaviors, we conducted a cohort analysis at two years of follow-up. Self-reported activity and Obesity and Weight-Loss Quality Of Life (OWLQOL) were analyzed for individual-level associations using linear mixed models accounting for random worksite effects. Results Gender modified the BMI-OWLQOL relationship, so analyses were conducted for males and females separately. Adjusting for demographic confounders, baseline OWLQOL, and several worksite-level variables including intervention arm, a 1.9 unit decrease in BMI (the interquartile range) was associated with an OWLQOL increase of 1.7 (95% CI: 1.2, 2.2) in males and 3.6 (95% CI: 3.2, 4.0) in females. Similarly, a 23 unit increase in physical activity score was associated with an OWLQOL increase of 0.9 (95% CI: 0.5, 1.4) in males and 1.6 (95% CI: 1.0, 2.3) in females. Physical activity associations were attenuated when adjusting for change in BMI, but remained significant for women (mean BMI 27.8 kg/m2). Conclusions This is the first study to demonstrate that increasing physical activity may improve obesity-specific QoL to a greater extent in women, particularly among overweight women, independent of BMI. Results may inform the design of interventions tailored to women targeting well-being through messages of increasing physical activity.