Functional Fitness and Objectively Measured Movement Behaviors in Relation to Arterial Stiffness in Older Adults: Age Emerges as the Only Independent Correlate After Multivariable Adjustment

Background: Central arterial stiffness assessed by carotid–femoral pulse wave velocity (PWVc-f) strongly predicts cardiovascular risk. We examined associations of objectively measured physical activity, sedentary behavior, and functional fitness with PWVc-f in community-dwelling older adults. Methods: The study included 170 older adults (124 women; 64–91 years). Moderate-to-vigorous physical activity (MVPA) and sedentary behavior were assessed by accelerometry, functional fitness by the Fullerton Functional Fitness Test (composite score), and PWVc-f by applanation tonometry. Associations were examined using correlation, hierarchical linear regression, and logistic regression analyses. Results: Elevated arterial stiffness (PWVc-f > 10 m/s) was present in 62.3% of participants. PWVc-f was associated with all functional fitness measures, including the composite score (ρ = −0.338, p < 0.001), but not with MVPA or sedentary behavior. High functional fitness was associated with lower odds of elevated PWVc-f in unadjusted analyses (OR = 0.39, 95% CI 0.20–0.78; p = 0.007), but this was no longer significant after adjustment for age, sex, and anthropometric/clinical characteristics. Neither MVPA nor sedentary behavior predicted PWVc-f. Age remained the only independent correlate across all models. Conclusions: Functional fitness showed stronger unadjusted associations with PWVc-f than MVPA or sedentary behavior. However, after multivariable adjustment including sex and clinical covariates, age emerged as the only consistent independent correlate of PWVc-f. These findings highlight the importance of considering age when interpreting the relationship between functional fitness and arterial stiffness in older adults.