Associations of physical activity domains and delayed biological aging: assessing heterogeneity and interaction of effects

Physical activity (PA) is widely recognized for its physical and mental health benefits, but the effects of different PA domains on delayed biological aging remain inconclusive. This study aimed to investigate the specific effects of occupational PA (OPA), transportation PA (TPA), and leisure-time PA (LTPA) on delayed biological aging, as well as the heterogeneity and joint interactions of these effects. We analyzed data from 18,362 adults in NHANES 2007-2010 and 2015-2018. Biological aging was assessed using Klemera-Doubal Method Biological Age (KDM-BA), Phenotypic Age (PhenoAge), and Homeostatic Dysregulation (HD). Delayed aging was defined as biological age acceleration < 0 for KDM-BA and PhenoAge, and as values below the median for HD. Logistic regression models were applied to estimate associations of PA domains and levels with delayed aging, and joint analyses were conducted to examine combined effects. Results showed that high OPA was associated with a lower likelihood of delayed aging (KDM, OR=0.84, 95% CI=0.78-0.91; PhenoAge, OR=0.86, 95% CI=0.79-0.94), whereas high LTPA (PhenoAge, OR=1.35, 95% CI=1.22-1.49; HD, OR=1.18, 95% CI=1.09-1.29) was associated with a higher likelihood, while associations for TPA were not significant after adjustment. Joint analysis showed that combinations with high OPA were associated with lower likelihood of delayed aging, whereas those with high LTPA were associated with higher likelihood. These findings highlight the distinct roles of different PA domains and levels in delaying biological aging, providing important evidence for public health strategies to promote healthy aging.