Reproducibility of ratings of perceived exertion soon after myocardial infarction: responses in the stress-testing clinic and the rehabilitation gymnasium

The purpose of this study was to compare ratings of perceived exertion (RPE; Borg's 6-20 scale) at the same exercise intensity, between a standard exercise electrocardiogram (ECG) treadmill stress test (exECG) and two subsequent bouts of treadmill exercise in a cardiac rehabilitation gymnasium. Eleven patients (mean ± s) 60.8 ± 6.1 years performed an exECG within 12.1 ± 7.5 d after myocardial infarction (MI) and commenced their first exercise-based rehabilitation session (gym-1), which included the use of a motorised treadmill, within 5.0 ± 1.3 d after the exECG. A second gym session (gym-2) was performed within 4.2 ± 1.3 d of gym-1. Gym-1 and gym-2 treadmill exercise was performed at an intensity that equated to the penultimate testing stage of exECG, and RPE and heart rate were compared at this level between the three sessions of testing. The mean work rate at the penultimate testing stage of the exECG was 6.0 ± 1.0 metabolic equivalents; ∼67% of peak work rate. The RPE at this work rate during exECG, gym-1 and gym-2 were 15.8 ± 2.7, 13.3 ± 3.4 and 13.0 ± 3.6, respectively. A repeated measures ANOVA revealed these RPE responses to be significantly different (F 2, 20 = 9.8; p = 0.001). Post-hoc Bonferroni-corrected pairwise t-tests showed significant differences (p ≤ 0.008) between exECG and gym-1 and exECG and gym-2 but not between gym-1 and gym-2. There was no significant difference in heart rate between the three testing sessions (p = 0.076) but it showed signs of a similar trend to RPE. The intra-participant agreement in RPE between gym-1 and gym-2 was substantial; intraclass correlation coefficient (ICC 2,1 ) = 0.85 (p