Physical Activity Domains/Recommendations and Leukocyte Telomere Length in U.S. Adults

Purpose The purpose of this study was to examine the associations between different physical activity (PA) domains, PA recommendations, and leukocyte telomere length (LTL) using data from a nationally representative sample of U.S. adults in the National Health and Nutrition Examination Survey, 1999-2002. Methods A total of 6933 U.S. adults (3402 men, 3531 women; age range: 20-84 yr) who completed demographic, general health and PA questionnaires and provided a blood sample were included in the analyses. Multivariable-adjusted linear regression models were used to determine associations between PA (domain-specific PA [household/yard work PA, transportation PA, moderate leisure time PA (LTPA), and vigorous LTPA], total moderate PA and PA recommendation groups), and log-transformed LTL adjusting for age, gender, education, cigarette smoking, alcohol consumption, and body mass index. Results On average, an increase of 1 h·wk ^-1 of vigorous LTPA was associated with a 0.31% (P < 0.001) longer LTL, and an increase of 1 h·wk ^-1 of household/yard work PA was associated with a 0.21% (P = 0.03) shorter LTL while adjusted for sociodemographic and health behavior covariates. Neither transportation PA nor moderate LTPA was significantly associated with LTL. In addition, compared with not meeting the PA recommendation (<150 min·wk ^-1), exceeding the recommended PA levels (≥300 min·wk ^-1) was positively associated with longer LTL (P = 0.04), whereas there was no difference in telomere length between those not meeting versus those meeting the PA recommendation (150-299 min·wk ^-1). Conclusion Greater engagement in vigorous LTPA and exceeding the PA recommendation may have a protective effect against telomere shortening. Future studies should examine the association between PA and LTL by exploring potential mediators such as sedentary behavior, genetics, nutrition, and chronic diseases.