Cardiorespiratory exercise intensity prescription in cardiovascular rehabilitation: do updated guideline recommendations reflect real individual effort responses?

AIMS: To evaluate how accurately the updated AHA/AACVPR Scientific Statement prescribes moderate-intensity exercise based on percentage of heart rate reserve (%HRR), by comparing it with heart rate (HR) at ventilatory thresholds in patients with cardiometabolic disease (CMD). METHODS: This retrospective multicentre study included 2,554 individuals from 12 centres across nine countries. HR at the first and second ventilatory thresholds (VT1, VT2), obtained by cardiopulmonary exercise testing (CPET), was compared with HR estimated from the guideline-defined moderate-intensity range (40-59% HRR). Agreement was assessed using Bland-Altman analysis, calibration using Passing-Bablok regression, and prediction error using mean absolute error. RESULTS: HR at VT1 closely approximated the lower limit (40% HRR), with minimal bias and a mean absolute error of 6.4 bpm. In contrast, HR at VT2 was substantially higher than the upper limit (59% HRR), with a negative bias (-11.4 bpm) and greater prediction error (mean absolute error of 12.0 bpm). Calibration analysis showed minor deviation at VT1 but marked systematic and proportional bias at VT2, indicating miscalibration at higher intensities. These findings were consistent across subgroup analyses. CONCLUSION: The AHA/AACVPR %HRR-based recommendations accurately reflect the lower boundary of moderate-intensity exercise but underestimate the transition to higher intensities. Aligning %HRR-based prescriptions with CPET-derived physiological thresholds are likely to improve the precision and effectiveness of exercise prescription in cardiac rehabilitation, while also strengthening methodological rigor and supporting more accurate interpretation of research findings.