Interval training for patients with coronary artery disease: a systematic review

Interval training (IT) may induce physiological adaptations superior to those achieved with conventional moderate-intensity continuous training (MCT) in patients with coronary artery disease (CAD). Our objectives were (1) to systematically review studies which have prescribed IT in CAD, (2) to summarize the findings of this research including the safety and physiological benefits of IT, and (3) to identify areas for further investigation. A systematic review of the literature using computerized databases was performed. The search yielded two controlled trials and five randomized controlled trials (RCTs) enrolling 213 participants. IT prescribed in isolation or in combination with resistance training was shown to induce significant and clinically important physiological adaptations in cardiac patients. IT was also shown to improve cardiorespiratory fitness (e.g. VO_2max, VO_2AT), endothelial function, left ventricle morphology and function (e.g. ejection fraction) to a significantly greater extent when compared with conventional MCT. No adverse cardiac or other life-threatening events occurred secondary to exercise participation in these studies. However, these findings must be interpreted with caution, as methodological limitations were present in all trials reviewed. In conclusion, robustly designed RCTs with thorough and standardized reporting are required to determine the risk and benefits of IT in the broader cardiac patient population. Further research is required to determine optimal IT protocols for the use in cardiac rehabilitation programmes, potentially contributing to novel exercise prescription guidelines for this patient population.