High Versus Moderate Intensity Exercise Training after Coronary Bypass Surgery

Abstract

PURPOSE: To determine the effect of high versus moderate intensity exercise training in a residential rehabilitation setting upon peak oxygen uptake (VO2peak). METHODS: 57 coronary artery bypass graft (CABG) patients referred to a residential rehabilitation centre 4–15 weeks post surgery were randomised to moderate (n = 29) or high (n = 28) intensity exercise training. Subjects walked on a treadmill 5 times per week during a 4 weeks rehabilitation period. The moderate intensity group carried out 46 minutes of walking at 70% of peak heart rate at pre-test (HRpeak), while the high intensity group carried out 4×4 minutes intervals at 85–95% of HRpeak with lower intensity periods in between. Total training volume was similar in both groups. In addition, the subjects participated in the ordinary training program at the centre, which consisted of both high and moderate intensity training. At discharge, the subjects were advised to continue training with the intensity they were randomised to. Subjects were re-tested after the rehabilitation period and again 6 months after discharge from the centre. SUMMARY OF RESULTS: Subjects performed on average 17 supervised treadmill sessions (range 14–18). VO2peak increased significantly in both groups, from 26.3 (SD 5.3) to 28.6 (SD 5.7) ml/min/kg in the moderate intensity group (p<0.0001) and from 27.3 (SD 4.4) to 30.5 (5.5) ml/min/kg (p<0.0001) in the high intensity group, with no significant difference between groups. So far, 17 patients in each group have been tested 6 months after the rehabilitation period: The high intensity group showed a significant increase from post-test of 6.6% (SD 8.7) in VO2peak (p < 0.005), while the moderate group showed no increase (0.6%, SD 9.6, p = 0.7). No significant changes in blood cholesterol were observed during the stay in the two groups. As a total however, the patients had a significant increase of 6.6% (p<0.05) in HDL. CONCLUSION: Moderate and high intensity training, in addition to a regular rehabilitation program, equally increases VO2peak in patients undergoing 4 weeks residential rehabilitation after coronary bypass surgery. Preliminary 6 months follow-up data suggest a further increase in the high intensity group only.