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.
(© 2023. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)