Exercise prescription guidelines for individuals undergoing cardiovascular rehabilitation (CR) are often based on heart rate training zones and rating of perceived exertion (RPE). United Kingdom guidelines indicate that patients should exercise at an intensity of RPE 11 to 14.

We aimed to determine the accuracy of this approach by comparing this RPE range with an objectively measured marker of exercise intensity, the ventilatory anaerobic threshold (VAT), and examine whether baseline directly determined cardiorespiratory fitness (CRF) affects the association between VAT and RPE.

Participants underwent a maximal cardiopulmonary exercise test before an 8-week community-based CR programme. Peak oxygen uptake (V̇O_2peak) and VAT were recorded, and RPE at the workload at which VAT was identified was recorded. Data were then split into tertiles, based on VO_2peak, to determine whether RPE at the VAT differed in participants with low, moderate or higher CRF.

We included 70 individuals [mean (SD) age 63.1 (10.0) years; body mass index 29.4 (4.0) kg/m²; 86% male]. At baseline, the mean RPE at the VAT (RPE@VAT) was 11.8 (95% confidence interval 11.0–12.6) and significantly differed between low and high CRF groups (P<0.001). The mean RPE@VAT was 10.1 (8.7–11.5), 11.8 (10.5–13.0), and 13.7 (12.5–14.9) for low, moderate and high CRF groups, respectively.

When using RPE to guide exercise intensity in CR populations, one must consider the effect of baseline CRF. Mean RPEs of ∼10, 12 and 14 correspond to the VAT in low, moderate and higher-fit patients, respectively.