Reallocation of Time Between Sedentary Behavior and Physical Activity In Relation to Biological Aging.

BACKGROUND/OBJECTIVES: To evaluate the associations between sedentary behavior and physical activity (PA) with biological aging and the effect on biological aging of replacing sedentary behavior with an equal amount of time spent on different PA. METHODS: A total of 301,603 U.K. adults (aged 38-73 years) were included. Sedentary behavior was quantified by summing up the time spent on watching TV, using computer, and driving every day. PA was quantified by the duration and frequency of light, moderate, and vigorous PA. Biological aging was estimated by PhenoAge algorithms based on clinical traits. Linear regression and isotemporal substitution model were used to test the relationships of sedentary behavior and PA with biological aging. RESULTS: Compared with individuals with sedentary behavior ≤3 hr/day, those with sedentary behavior of 3-5, 5-8, and >8 hr/day were associated with higher biological age acceleration, respectively. Consistently, PA was associated with lower biological age acceleration (p < .001). The isotemporal substitution model suggested that replacing sedentary behavior with PA (in hours per day) can delay biological age acceleration (light PA: β = -0.12, 95% CI [-0.14 to -0.09]; moderate PA: β = -0.22, 95% CI [-0.25 to -0.18]; vigorous PA: β = -0.21, 95% CI [-0.28 to -0.14). Multiplicative interactions were observed between sedentary behavior and all type of PA on biological age acceleration (p for interaction <.001). CONCLUSION: Based on UK Biobank cohort, sedentary behavior and lack of PA were associated with accelerated biological aging, while replacing sedentary behavior with PA was linked to slower biological aging. Significance/Implications: To delay biological aging, the population should replace sedentary behaviors with PA.