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 of vigorous LTPA was associated with a 0.31% (P < 0.001) longer LTL, and an increase of 1 h·wk 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), exceeding the recommended PA levels (≥300 min·wk) 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).

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.