Associations of physical activity patterns with sarcopenia prevalence and all cause mortality among adults in the United States

Sarcopenia is an age-related degenerative condition of skeletal muscle that impairs health and quality of life in middle-aged and older adults. Physical activity (PA) is an important modifiable factor, yet the effects of different PA domains—leisure-time (LPA), occupational (OPA), and transportation-related (TPA)—on sarcopenia and mortality remain unclear. Data were obtained from the National Health and Nutrition Examination Survey (NHANES) 1999–2018, including 4,963 participants with available dual-energy X-ray absorptiometry (DXA) data. Sarcopenia was defined using appendicular lean mass based on FNIH criteria. Multivariable logistic regression examined associations between PA patterns and sarcopenia prevalence, and Cox proportional hazards models assessed relationships with all-cause mortality. Restricted cubic splines (RCS) explored potential nonlinear associations, and Kaplan-Meier analysis compared survival differences. Among the 4,963 participants, 676 had sarcopenia and 98 deaths occurred during follow-up. Higher levels of LPA, OPA, and TPA were inversely associated with sarcopenia prevalence ( P < 0.01). In contrast, among individuals with sarcopenia, higher levels of LPA and TPA were associated with a higher risk of all-cause mortality relative to the lowest activity category ( P < 0.05). RCS analyses indicated a nonlinear association between TPA and mortality, characterized by an inverted U-shaped pattern. Different PA domains exhibited differential associations with sarcopenia and mortality. While higher PA levels were associated with a lower prevalence of sarcopenia in the general population, PA–mortality associations among individuals with sarcopenia varied by activity level and domain. These findings highlight the importance of considering baseline health status when interpreting PA–mortality relationships and support the need for tailored PA recommendations.