Association of dynapenia with adverse physical function trajectories in community-dwelling adults: a CHARLS cohort study

The 2025 Asian Working Group for Sarcopenia (AWGS 2025) consensus redefined sarcopenia as low muscle strength with concomitant low muscle mass and repositioned physical performance as a downstream outcome. Longitudinal evidence on how sarcopenia-related phenotypes relate to subsequent physical performance trajectories remains limited. This prospective cohort study included 2,657 community-dwelling adults aged ≥50 years with preserved baseline physical function (SPPB >9) from the China Health and Retirement Longitudinal Study. Participants were categorized as Normal, Low muscle, Dynapenia, or operationally defined Sarcopenia using criteria informed by the AWGS 2025 conceptual framework. Latent class mixed models identified longitudinal SPPB trajectories, and multivariable multinomial logistic regression examined associations between baseline phenotypes and trajectory membership. Three SPPB trajectories were identified: High-stable (86.4%), Moderate-stable (10.4%), and Rapidly-declining (3.2%). After adjustment for age, sex, waist circumference, smoking status, and hypertension, dynapenia was associated with higher odds of Moderate-stable (OR 1.76, 95% CI 1.18–2.61) and Rapidly-declining (OR 2.40, 95% CI 1.30–4.42) membership, relative to the normal phenotype, with High-stable as the reference trajectory. Low muscle mass alone and operationally defined sarcopenia were also associated with Moderate-stable membership, whereas their associations with Rapidly-declining membership were inconclusive. Among community-dwelling adults aged ≥50 years with preserved baseline physical function, distinct patterns of functional change emerged over four years. These findings support an association between low muscle strength and subsequent patterns of functional deterioration, but do not establish superior prognostic value over sarcopenia.