Is interval training (HIIT) better for my heart than regular cardio?
HIIT delivers slightly more benefit for your cardiovascular fitness than regular cardio. The difference is not enormous, but across several patient groups it is genuinely meaningful. Do you have heart problems or risk factors? Then consult a doctor first.
HIIT, alternating between short intensive bursts and recovery periods, improves your cardiovascular fitness slightly more than regular cardio. It is not a dramatic difference, but across several patient groups it is clinically meaningful. Context plays a major role here.
The strongest evidence comes from cardiac rehabilitation in people with stable coronary artery disease. HIIT improved maximum oxygen uptake by an average of 2.37 ml/kg/min; regular cardio did so by 1.32 ml/kg/min. There was only one serious adverse event that may have been related to HIIT, suggesting an acceptable safety profile1. A Mayo Clinic review confirms that HIIT is safe and effective in older cardiac patients, provided it is properly supervised2.
In stroke patients, HIIT also outperforms regular cardio: a review of 28 studies shows an advantage of +2.9 ml/kg/min for cardiovascular fitness and walking ability. The evidence is moderate and larger studies are needed3,4. In people with rheumatoid arthritis, HIIT combined with strength training yielded more than 3.7 ml/kg/min extra compared to the control group, without increased pain or joint inflammation5.
In Parkinson's disease, HIIT improved cardiovascular fitness more than regular cardio (+3.7 versus +1.7 ml/kg/min), but the difference was not statistically significant in a small study of 29 participants. That is preliminary evidence6. European experts strongly recommend HIIT in cases of overweight or obesity for improved insulin sensitivity and cardiovascular fitness, explicitly only after a cardiac risk assessment and under supervision7.
Importantly, all of these studies were conducted under supervision in people whose hearts were assessed beforehand. Do you have cardiovascular disease, risk factors such as obesity or diabetes, or are you older? If so, consult a doctor before starting intensive interval training.
All claims are based on RCTs, network meta-analyses and a clinical review article (6 PMIDs). The strongest claim, concerning coronary artery disease (PMID 36753063), comes from a meta-analysis with causal evidence. The remaining claims range from moderate to limited evidence. None of the studies had healthy adults without a medical condition as their primary target group.