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].