Effects of High-Intensity Interval Training versus Moderate-Intensity Continuous Training on Cardiovascular Outcomes in Patients with Cardiovascular Disease

For patients in cardiac rehabilitation, the standard exercise prescription is steady, moderate effort. This meta-analysis asks whether short bursts of high intensity — HIIT — do more.

Pooling 19 randomized trials and over 1,300 patients with cardiovascular disease, the answer leans toward HIIT. It produced significantly greater gains than moderate continuous training in peak oxygen uptake (the best single measure of cardiorespiratory fitness), in flow-mediated dilation (a marker of blood-vessel health), and in left ventricular ejection fraction (the heart’s pumping strength).

The practical takeaway is that cardiac rehab programs should consider building in HIIT for patients who can do it safely, to extract larger fitness and vascular gains. The resistance is understandable caution — risk-averse programs hesitant to push cardiac patients to high intensity.

We rate the evidence solid: a methodologically rigorous meta-analysis of 19 RCTs with no disclosed conflicts. Its clinical significance is moderate-to-high — better fitness and cardiac function are meaningful and plausibly translate to better outcomes — tempered by the need for appropriate patient selection and monitoring, since HIIT isn’t suitable for everyone.