Subjective Ratings of Perceived Exertion in Cardiac Rehabilitation Programs: what can we Rely on to Predict Exercise Tolerance?

Abstract

Background: Borg’s Rating of Perceived Exertion (RPE) is a simple and convenient method for monitoring exercise intensity. However, it’s based on subjective feeling of exertion and fatigue during exercise, and possible factors that influence perception are highly variable inter and intra-individually.

Objective: To evaluate the predictors of a higher RPE at the beginning of a cardiac rehabilitation program (CRP).

Methods: Patients enrolled in a cardiac rehabilitation program after an acute coronary event between September 2008 and October 2010. Psychosocial profile at admission was characterized using Hospital Anxiety and Depression Scale (HADS) and the Medical Outcomes Study Short Form – 36 (SF-36). Functional status was estimated using both physical components of the SF-36 and exercise intensity in metabolic equivalents (MET) achieved at baseline exercise stress testing (EST). We used peak exercise perception score (PEPS=RPE/MET) to determine level of fatigue indexed to exercise intensity level during the first exercise training session.

Results: One-hundred seventy five patients were analysed, 160(91,4%) were male, mean age [mean(SD): 53(9)] years and had low level of education [P50(P25-P75):6(4.-11)]. Treatment after the acute coronary event consisted of percutaneous coronary revascularization in 144 (82,3%), coronary artery bypass graft surgery in 19 (10,9%) and 12 (6,9%) patients received only medical treatment. Mean exercise capacity was 10 (2,0) MET at baseline EST and the perception of overall physical ability in daily activities scored 46,2 (8,1) in summary physical component of SF36.

During initial exercise training sessions, we found a 2,27(0,6) increase in RPE per 1 MET increase in exercise intensity. Univariate determinants of exercise perception were gender (b=-0.23; p=0.003), years of education (b=- 0.32; p<0.001), maximum volume ventilation (MVV) (b=-0.29 per 10% of MVV increase; p<0.001), functional status at admission [SF-36v2 physical domains (b=-0.34; p<0.001); peak MET level at EST (b=-0.32; p<0.001)] and psychosocial profile at admission [HADS≥8 (b=0.18; p=0.02); SF-36 summary mental component (b=- 0.20;p=0.009)]. Age and sex-adjusted multivariate analysis identified level of education (b=-0.24; p=0.001), MVV (b=-0.19 per 10% of MVV increase; p=0.008), SF-36v2 physical domains (b=-0.19; p=0.011), MET level at EST (b=- 0.20; p=0.009), as predictor variables.

Conclusions: Effort perception is multifactorial depending upon a complex interplay between psychosocial and physical capacities. Indentifying their main determinants may allow for more individualized interventions in CRP resulting in a better functional recovery, social participation and quality of life.

Keywords: Coronary Heart Disease; Cardiac Rehabilitation; Physical Exertion.