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 (VO2) [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. [ABSTRACT FROM AUTHOR]