Across 12,944 older adults in three nationally representative cohorts — China's CHARLS, England's ELSA, and the US HRS — each one standard-deviation increase in estimated cardiorespiratory fitness (eCRF) was associated with a 39% lower hazard of developing cardiometabolic multimorbidity (CMM), defined as two or more conditions among hypertension, diabetes, heart disease, and stroke. Those in the highest fitness category faced a striking 60% lower risk (HR 0.40, 95% CI 0.35–0.45) compared to the lowest, with 3,029 incident CMM cases observed over follow-up. Crucially, eCRF was derived from a validated non-exercise equation — requiring no treadmill or lab test — and still meaningfully improved risk discrimination when added to standard sociodemographic and behavioral predictors.
This finding is notable because CMM is increasingly recognized as a critical driver of disability and healthcare burden in aging populations worldwide, yet most risk models rely on individual diseases rather than co-occurring clusters. The cross-national consistency of the association — spanning three distinct health systems and ethnic populations — strengthens generalizability beyond prior single-cohort work. That said, this is a preprint not yet peer-reviewed, and several cautions apply: the observational design precludes causal inference, eCRF equations carry inherent estimation error, and the authors themselves flag meaningful between-cohort heterogeneity. Still, the practical implication is clear: a non-exercise fitness estimate, derived from routine clinical data, may serve as an actionable screening tool for multimorbidity risk in aging adults — an incremental but genuinely useful advance.
