Interval training confers greater gains than continuous training in people with heart failure.

QUESTION: Is aerobic interval training (AIT) more effective than moderate continuous training (MCT) at enhancing aerobic fitness and myocardial remodelling in patients with stable heart failure?

DESIGN

Randomised controlled trial in which participants were allocated to AIT, MCT, or a control group.

SETTING

Hospital in Trondheim, Norway.

PARTICIPANTS

Adults with stable heart failure post myocardial infarction with left ventricular ejection fraction (EF) < 40% on optimal medical management. Exclusion criteria comprised: unstable angina pectoris, uncompensated heart failure, myocardial infarction within four weeks, complex ventricular arrhythmias, no use of Đ-blockers and ACE inhibitors or, any other limitation to exercise. Randomisation of 27 patients allocated nine to each group.

INTERVENTIONS: The AIT and MCT groups completed two supervised exercise training sessions and one home training session each week for 12 weeks. Those in AIT completed uphill treadmill walking that comprised a warm-up and cool down interspersed with 4 × 4 minute exercise intervals completed at 90-95% of peak heart rate. Intervals were separated by three minutes of walking at 50-70% of peak heart rate (total exercise time = 38 minutes). The MCT participants walked continuously for 47 minutes at 70-75% of peak heart rate. Weekly home training comprised outdoor hill walking. The control group completed 47 minutes of supervised treadmill walking at 70% of peak heart rate once every three weeks.

OUTCOME MEASURES: The primary outcomes related to exercise capacity (eg, peak rate of oxygen uptake; VO(2peak)); secondary outcomes comprised measures of echocardiography and endothelial function.

RESULTS

Outcomes were available from 26 participants. The VO(2peak) achieved on completion of training was greater in the AIT group compared with the MCT group (mean difference 4.1; 95% CI 2.4 to 5.8ml/kg/min) and the control group (5.8, 95% CI 3.8 to 7.8ml/kg/min). Compared with the other groups, AIT also conferred greater gains in measures of systolic and diastolic function and endothelial function.

CONCLUSION

In adults with stable heart failure, AIT conferred greater gains than MCT in improving aerobic capacity and measures reflecting left ventricular and endothelial function. [Mean difference and 95% CIs calculated by the CAP Editor].