Physical Activity Trajectories: Consequences for Sarcopenia Risk Among Middle-Aged and Older Adults.

PURPOSE: This study aimed to identify distinct physical activity (PA) trajectories among middle-aged and older adults using group-based trajectory modeling and to examine whether these trajectories were associated with different sarcopenia-related profiles. METHODS: Data were obtained from 2029 individuals aged 40 years and older who participated in the China Health and Retirement Longitudinal Study in 2011, 2013, and 2015. PA was assessed using the International Physical Activity Questionnaire. Sarcopenia-related outcomes included low muscle strength, poor physical performance, low muscle mass, possible sarcopenia, and sarcopenia. RESULTS: Compared with the low-stable group, individuals in the moderate-stable group had lower odds of poor muscle strength (adjusted odds ratio [aOR] = 0.70; 95% CI, 0.52-0.93) and sarcopenia (aOR = 0.58; 95% CI, 0.39-0.88). Individuals in the high-stable group had lower odds of poor muscle strength (aOR = 0.70; 95% CI, 0.51-0.97), poor physical performance (aOR = 0.73; 95% CI, 0.54-0.98), and sarcopenia (aOR = 0.57; 95% CI, 0.36-0.91). Stratified analyses suggested sex- and age-specific association patterns, with significant associations mainly involving muscle strength and muscle mass in men and physical performance and possible sarcopenia in women. Subgroup analyses suggested that these associations differed by sex and were more evident in older age groups. CONCLUSIONS: Distinct PA trajectories were associated with different patterns of sarcopenia-related risk among middle-aged and older adults. These findings suggest that trajectory-based PA assessment may provide additional information beyond single-time PA measures and support more refined muscle health risk stratification.