Exercise prescription using resting heart rate plus 20 or perceived exertion in cardiac rehabilitation.
OBJECTIVE
For patients starting a cardiac rehabilitation program, exercise intensity often is set 20 beats per minute above the standing resting heart rate (RHR+20) or in a range of 11 to 13 on Borg's Scale for Rating of Perceived Exertion (RPE 11-13). The purpose of this study was to determine the actual exercise intensity, expressed as a percentage of peak oxygen uptake reserve (%VO2R) using these techniques.


METHODS
For this study, 11 new referrals to a phase 2 cardiac rehabilitation program voluntarily underwent a symptom-limited exercise test and a field test that consisted of self-paced over-the-ground walking for 10 minutes at levels corresponding to RPE 11-13 and RHR+20. During both tests, gas exchange data were obtained via the Cosmed K4b and heart rate via the Polar monitor.


RESULTS
The mean %VO2R at RHR+20 (41.8 +/- 12.3%) and RPE 11-13 (71 +/- 15.3% mL.kg.min) were significantly different. Exercise at RHR+20 resulted in 4 of the 11 patients (36%) exercising at less than 40% VO2R, 6 of the patients (55%) exercising at 40% to 60% VO2R, and 1 of the patients (9%) exercising at more than 60% VO2R. Exercise at RPE 11-13 resulted in 1 of the 11 patients (9%) exercising at less than 40% VO2R, 1 of the patients at exercising at 40% to 60% VO2R (9%), and 9 of the patients (82%) exercising at more than 60% VO2R.


CONCLUSIONS
The results of this study indicate that using RHR+20 or RPE 11-13 to prescribe exercise intensity during over-the-ground walking for phase 2 cardiac rehabilitation patients results in substantial intersubject variability and raises questions about the safety and efficacy of these approaches.
Joo
Kee-Chan
KC
Department of Sports and Health Science, Seowon University, Korea.
Brubaker
Peter H
PH
MacDougall
Andrew
A
Saikin
Aaron M
AM
Ross
James H
JH
Whaley
Mitchell H
MH
D000328:Adult; D001794:Blood Pressure / Q000502:physiology; D004562:Electrocardiography; D005080:Exercise Test / Q000009:adverse effects / Q000379:methods; D005081:Exercise Therapy / Q000009:adverse effects / Q000379:methods*; D005260:Female; D006331:Heart Diseases / Q000534:rehabilitation*; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption / Q000502:physiology; D010465:Perception / Q000502:physiology*; D005082:Physical Exertion / Q000502:physiology*; D011446:Prospective Studies; D012146:Rest / Q000502:physiology; D013997:Time Factors; D016138:Walking / Q000502:physiology