Relationship between ratings of perceived exertion and MET levels during graded exercise testing in early outpatient cardiac rehabilitation

Abstract

The purpose of this study was to evaluate the relationship between ratings of perceived exertion (RPE) and MET levels during four graded exercise tests (GXTs) in early outpatient (Phase II) cardiac rehabilitation. Thirty post-coronary artery bypass and valve replacement surgery patients were tested on the day prior to hospital discharge, a LLGXT (T1); two weeks post-discharge, a FGXT (T2); four weeks post-discharge, a FGXT (T3); and eight weeks post-discharge, a SLM-GXT (T4). Mean peak heart rate (HR), RPE, and MET levels were calculated. A Scheffe post-hoc revealed significant (p .01) differences in RPE between T1 and T4, and T2 and T4. Significant changes in MET levels were also noted between T1 and T2 (p .05), and between all other GXTs (p .01). Mean correlation coefficients (r) and individual regression equations were developed for each subject for each GXT. Mean beta-coefficients and Y-intercepts were also calculated. A one-way ANOVA with repeated measures revealed significant F values. A Scheffe post-hoc analysis revealed significant differences in the slopes of the calculated regression lines between T1 and T3 (p .01), T1 and T4 (p .01), and T2 and T4 (p .05). The decline in the slopes of the calculated regression represented progressively greater MET capacities at the same RPE. It was concluded that as a result of postsurgical recovery and exercise training, perception shifts occurred to yield the same RPE at higher MET levels.