Aerobic Interval vs. Continuous Training in Patients with Coronary Artery Disease or Heart Failure: An Updated Systematic Review and Meta-Analysis with a Focus on Secondary Outcomes

Background In a previous meta-analysis including nine trials comparing aerobic interval training with aerobic continuous training in patients with coronary artery disease, we found a significant difference in peak oxygen uptake favoring aerobic interval training. Objective The objective of this study was to (1) update the original meta-analysis focussing on peak oxygen uptake and (2) evaluate the effect on secondary outcomes. Methods We conducted a systematic review with a meta-analysis by searching PubMed and SPORTDiscus databases up to March 2017. We included randomized trials comparing aerobic interval training and aerobic continuous training in patients with coronary artery disease or chronic heart failure. The primary outcome was change in peak oxygen uptake. Secondary outcomes included cardiorespiratory parameters, cardiovascular risk factors, cardiac and vascular function, and quality of life. Results Twenty-four papers were identified (n = 1080; mean age 60.7 +/- 10.7 years). Aerobic interval training resulted in a higher increase in peak oxygen uptake compared with aerobic continuous training in all patients (1.40 mL/kg/min; p < 0.001), and in the subgroups of patients with coronary artery disease (1.25 mL/kg/min; p = 0.001) and patients with chronic heart failure with reduced ejection fraction (1.46 mL/kg/min; p = 0.03). Moreover, a larger increase of the first ventilatory threshold and peak heart rate was observed after aerobic interval training in all patients. Other cardiorespiratory parameters, cardiovascular risk factors, and quality of life were equally affected. Conclusion This meta-analysis adds further evidence to the clinically significant larger increase in peak oxygen uptake following aerobic interval training vs. aerobic continuous training in patients with coronary artery disease and chronic heart failure. More well-designed randomized controlled trials are needed to establish the safety of aerobic interval training and the sustainability of the training response over longer periods.