Elsevier

American Heart Journal

Volume 158, Issue 6, December 2009, Pages 1031-1037
American Heart Journal

Clinical Investigation
Outcomes, Health Policy, and Managed Care
Aerobic interval training versus continuous moderate exercise after coronary artery bypass surgery: A randomized study of cardiovascular effects and quality of life

https://doi.org/10.1016/j.ahj.2009.10.003Get rights and content

Background

Peak oxygen uptake (Vo2peak) strongly predicts mortality in cardiac patients. We compared the effects of aerobic interval training (AIT) versus moderate continuous training (MCT) on Vo2peak and quality of life after coronary artery bypass grafting (CABG).

Methods

Fifty-nine CABG patients were randomized to either AIT at 90% of maximum heart rate or MCT at 70% of maximum heart rate, 5 d/wk, for 4 weeks at a rehabilitation center. Primary outcome was Vo2peak, at baseline, after rehabilitation (4 weeks), and after 6 months of home-based exercise (6 months).

Results

Vo2peak increased between baseline and 4 weeks in AIT (27.1 ± 4.5 vs 30.4 ± 5.5 mL·kg−1·min−1, P < .001) and MCT (26.2 ± 5.2 vs 28.5 ± 5.6 mL·kg−1·min−1, P < .001; group difference, not significant). Aerobic interval training increased Vo2peak between 4 weeks and 6 months (30.4 ± 5.5 vs 32.2 ± 7.0 mL·kg−1·min−1, P < .001), with no significant change in MCT (28.5 ± 5.6 vs 29.5 ± 5.7 mL·kg−1·min−1). Quality of life improved in both groups from baseline to 4 weeks, remaining improved at 6 months. There were no changes in echocardiographic systolic and diastolic left ventricular function. Adiponectin increased between 4 weeks and 6 months in both groups (group differences, not significant).

Conclusions

Four weeks of intense training increased Vo2peak significantly after both AIT and MCT. Six months later, the AIT group had a significantly higher Vo2peak than MCT. The results indicate that AIT and MCT increase Vo2peak similarly in the short term, but with better long-term effect of AIT after CABG.

Section snippets

Patients

Coronary artery bypass grafting patients referred to a residential rehabilitation center 4 to 16 weeks postoperatively were included. Exclusion criteria were heart failure, inability to exercise, or drug abuse.

Exercise training

The aerobic exercise training program consisted of treadmill walking, 5 days a week for 4 weeks. Patients were randomized to either AIT or MCT. Aerobic interval training consisted of 8 minutes warm-up, followed by 4 times of 4-minute intervals with HR at 90% of maximum HR, with active

Participant flow and protocol deviations

We recruited patients between April 2004 and November 2006 (Figure 1). Baseline characteristics of the 2 groups were well balanced (Table I). There were no major complications or cardiac events during the study period. One patient was excluded after randomization to MCT because of a large pericardial effusion that had not been discovered at the time of allocation. Oxygen uptake data on one patient in the AIT group were excluded from the analysis because of a technical error in the measurement.

Discussion

Our main finding was that both AIT and MCT training groups showed a significant increase in Vo2peak, HR recovery, and quality of life after a 4-week intense rehabilitation program (at 4w). At follow-up 6 months from discharge (6m), the AIT group showed a further increase in Vo2peak, whereas MCT did not.

Based on previous studies,4, 5, 6,14 we had hypothesized that AIT would increase Vo2peak more than MCT. After 4 weeks of exercise training, there was slight evidence for a greater increase in Vo

Conclusions

Vo2peak and HR recovery increased significantly after a brief but intense exercise program of both moderate continuous exercise training (MCT) and AIT in coronary artery bypass patients. Aerobic interval training was superior to MCT in increasing Vo2peak and HR recovery 6 months after ending the formal program. Quality of life increased significantly after 4 weeks of rehabilitation and remained improved for 6 months in both training groups.

Acknowledgements

We are sincerely indebted to the great work of Dr Ole Christen Haanæs who died during the study period. Great thanks to the patients and staff at Røros Rehabilitation Center for excellent cooperation and to Tomas Stølen for collection of data.

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