Telomere length is an index of cellular aging. Healthy lifestyles are associated with reduced oxidative stress and longer telomeres, whereas unhealthy behaviors are related to shorter telomeres and greater biological aging. This investigation was designed to determine if strength training accounted for differences in telomere length in a random sample of 4814 US adults. Data from the National Health and Nutrition Examination Survey (NHANES) were employed to answer the research questions using a cross-sectional design. Time spent strength training was calculated by multiplying days of strength training per week by minutes per session. Participation in other forms of physical activity was also calculated based on reported involvement in 47 other activities. Weighted multiple regression and partial correlation were used to calculate the mean differences in telomere length across levels of strength training, adjusting for differences in potential confounders. With the demographic covariates controlled, strength training and telomere length were linearly related (F = 14.7,