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

Abstract

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. We aimed to perform a novel large-scale meta-analysis on the effects of HIIT on cardiometabolic health in the general population. 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. 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): 3.895mlmin-1kg-1, P < 0.001), left ventricular ejection fraction (WMD: 3.505%, P < 0.001), systolic (WMD: - 3.203mmHg, P < 0.001) and diastolic (WMD: - 2.409mmHg, P < 0.001) blood pressure, resting heart rate (WMD: - 3.902bpm, P < 0.001) and stroke volume (WMD: 9.516mL, P < 0.001). Body composition also significantly improved through reductions in body mass index (WMD: - 0.565kgm-2, P < 0.001), waist circumference (WMD: - 2.843cm, P < 0.001) and percentage body fat (WMD: - 0.972%, P < 0.001). Furthermore, there were significant reductions in fasting insulin (WMD: - 13.684pmol L-1, P = 0.004), high-sensitivity C-reactive protein (WMD: - 0.445mg dL-1, P = 0.043), triglycerides (WMD: - 0.090mmol L-1, P = 0.011) and low-density lipoprotein (WMD: - 0.063mmol L-1, P = 0.050), concurrent to a significant increase in high-density lipoprotein (WMD: 0.036mmol L-1, P = 0.046). 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.