A Controlled Trial of Circuit Weight Training on Aerobic Capacity and Myocardial Oxygen Demand in Men After Coronary Artery Bypass Surgery

BACKGROUND: Cardiovascular benefits of resistance training in cardiac patients have been suggested but not studied in a randomized, controlled trial of circuit weight training (CWT) without an aerobic exercise component. The purpose of the current study was to examine the effects of 10 weeks of CWT on muscular strength, peak oxygen consumption (peak VO2), and myocardial oxygen demand (mVO2) in men after coronary artery bypass surgery. METHODS: Twenty-six, post-coronary bypass male subjects (mean 19 months after bypass), aged 60 +/- 8.5 years, were randomly allocated to 10 weeks of CWT at 40 to 60% of maximum voluntary contraction (n = 12) or to a control group (n = 14). Muscular strength was assessed using a modified one repetition maximum technique. Peak VO2 was recorded during symptom-limited treadmill exercise. Rate pressure product, as an indirect measure of mVO2, was measured during isometric, isodynamic, and dynamic exercise. RESULTS: No ischemic symptoms nor electrocardiographic changes were recorded during testing or training. Strength increased by 18% (P < 0.005) in five out of seven exercises in the training group, but was unchanged in the control group. Training did not improve peak VO2. Rate pressure product during isometric and isodynamic exercise decreased from pre- to post-testing (P < 0.05) but was equivalent to that seen in the control group. CONCLUSIONS: Moderate intensity CWT is safe and can improve strength in selected low-risk patients after coronary artery bypass surgery. However, it does not significantly increase peak VO2 nor reduce mVO2 during isometric, isodynamic, and dynamic exercise.