Longitudinal changes of cardiorespiratory fitness are associated with cardiovascular disease and mortality: evidence...

Cardiorespiratory fitness (CRF) is a strong predictor of cardiovascular disease (CVD) and mortality. However, whether longitudinal changes in CRF independently predict cardiovascular outcomes beyond baseline CRF remains unclear.

We analysed 11 530 UK Biobank participants (aged 40-73 years) who completed two CRF assessments via submaximal cycle ergometry. Annualized change in estimated VO₂max (mL·kg-1·min-1·year-1) was calculated as the difference between assessments divided by the time between the two measurements. After excluding participants with prior CVD or events within 2 years of follow-up, we identified incident CVD and CVD mortality through clinical records and self-reports. Cox models were adjusted for baseline CRF, sociodemographic and lifestyle behaviours, genetic predisposition to CVD, BMI change, and physical activity. Over a median follow-up of 14.0 years (interquartile range 13.0-14.6), 921 incident CVD events and 119 CVD-related fatalities occurred. Annual improvements in VO₂max were associated with a lower risk of incident CVD [hazard ratio (HR) per +1 mL·kg-1·min-1·year-1 = 0.85; 95% confidence interval (CI) 0.75-0.96] and CVD-related mortality (HR = 0.66, 95% CI 0.51-0.87). Conversely, declines in VO₂max were associated with increased CVD risk. Analyses demonstrated an approximately linear dose-response pattern, with progressively lower risk across the spectrum of positive VO₂max change and higher risk with negative change, without evidence of threshold effects.

An annual improvement as little as 1 mL/kg/min may be enough to lower CVD risk, independent of baseline CRF. Longitudinal assessment of CRF may enhance cardiovascular risk stratification and inform prevention strategies.