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Abstract
Exercise during cardiac rehabilitation (CR) leads to an improvement in functional capacity (FC). The purpose of this study was to determine the role of exercise prescription variables on FC change among CAD patients who complete 36 sessions of CR. Methods: Exercise testing and prescription data for 151 patients were extracted from the AACVPR registry and a local cardiac rehabilitation facility’s database. Patients completed a submaximal exercise test for determination of FC, measured in metabolic equivalents (METs), pre- and post- 36 sessions of CR. A regression equation to determine the influence of exercise prescription components (intensity, duration, frequency) on change in peak METs was established. Results: The average FC at pre- and post-CR was 4.4 ± 1.9 and 6.7 ± 1.7METs, respectively. The average increase in FC among patients was 2.2 ± 1.7METs. Over 36 CR sessions, patients averaged 10.92 ± 3.58 minutes of treadmill exercise at an intensity of 92 ± 25.7% of pre-CR peak METs. The regression equation established was: ΔMETs = -1.288–(0.024*age)+(0.331(*1 if men, *0 if women))+(0.417*frequency)+(0.109*treadmill duration) + (0.029*intensity) (R=0.536, SEE=1.44). Treadmill walking intensity and duration were significant predictors of change in FC (p<0.01). Frequency was not a significant predictor but was clinically meaningful. Conclusions: Every 35% increase in intensity averaged over 36 CR-sessions and every 10 minutes of treadmill exercise lead to an improvement of FC by 1 MET each. Therefore, clinical exercise physiologists and others on the CR team should strive to increase patient's treadmill walking duration and intensity continuously.