High-Intensity Interval Training and Cardiometabolic Health in the General Population: A Systematic Review and Meta-Analysis of Randomised Controlled Trials

Background High-intensity interval training (HIIT) remains a promising exercise mode in managing cardiometabolic health. Large-scale analyses are necessary to understand its magnitude of effect on important cardiometabolic risk factors and inform guideline recommendations. Objective We aimed to perform a novel large-scale meta-analysis on the effects of HIIT on cardiometabolic health in the general population. Methods PubMed (MEDLINE), the Cochrane library and Web of Science were systematically searched. Randomised controlled trials (RCTs) published between 1990 and March 2023 were eligible. Research trials reporting the effects of a HIIT intervention on at least one cardiometabolic health parameter with a non-intervention control group were considered. Results This meta-analysis included 97 RCTs with a pooled sample size of 3399 participants. HIIT produced significant improvements in 14 clinically relevant cardiometabolic health parameters, including peak aerobic capacity (VO 2 ) [weighted mean difference (WMD): 3.895 ml min −1 kg −1 , P < 0.001), left ventricular ejection fraction (WMD: 3.505%, P < 0.001), systolic (WMD: − 3.203 mmHg, P < 0.001) and diastolic (WMD: − 2.409 mmHg, P < 0.001) blood pressure, resting heart rate (WMD: − 3.902 bpm, P < 0.001) and stroke volume (WMD: 9.516 mL, P < 0.001). Body composition also significantly improved through reductions in body mass index (WMD: − 0.565 kg m −2 , P < 0.001), waist circumference (WMD: − 2.843 cm, P < 0.001) and percentage body fat (WMD: − 0.972%, P < 0.001). Furthermore, there were significant reductions in fasting insulin (WMD: − 13.684 pmol L −1 , P = 0.004), high-sensitivity C-reactive protein (WMD: − 0.445 mg dL −1 , P = 0.043), triglycerides (WMD: − 0.090 mmol L −1 , P = 0.011) and low-density lipoprotein (WMD: − 0.063 mmol L −1 , P = 0.050), concurrent to a significant increase in high-density lipoprotein (WMD: 0.036 mmol L −1 , P = 0.046). Conclusion These results provide further support for HIIT in the clinical management of important cardiometabolic health risk factors, which may have implications for physical activity guideline recommendations.