High-intensity interval training for cardiometabolic health in adults with metabolic syndrome: a systematic review and meta-analysis of randomised controlled trials

Objective To assess the effectiveness of high-intensity interval training (HIIT) compared with traditional moderate-intensity continuous training (MICT) and/or non-exercise control (CON) for modification of metabolic syndrome (MetS) components and other cardiometabolic health outcomes in individuals with MetS. Design Systematic review and meta-analysis Data sources Five databases were searched from inception to March 2024. Study appraisal and synthesis Meta-analyses of randomised controlled trials (RCTs) comparing HIIT with MICT/CON were performed for components of MetS (waist circumference (WC), systolic blood pressure (SBP), diastolic blood pressure (DBP), high-density lipoprotein cholesterol (HDL-C), triglyceride (TG), and fasting blood glucose (BG)) and clinically relevant cardiometabolic health parameters. Subgroup moderator analyses were conducted based on the intervention duration and HIIT volume. Results Out of 4819 studies, 23 RCTs involving 1374 participants were included (mean age: 46.2–67.0 years, 55% male). HIIT significantly improved WC (weighted mean difference (WMD) –4.12 cm, 95% CI –4.71 to –3.53), SBP (WMD –6.05 mm Hg, 95% CI –8.11 to –4.00), DBP (WMD –3.68 mm Hg, 95% CI –5.70 to –1.65), HDL-C (WMD 0.12 mmol/L, 95% CI 0.04 to 0.20), TG (WMD –0.34 mmol/L, 95% CI –0.41 to –0.27) and BG (WMD –0.35 mmol/L, 95% CI –0.54 to –0.16) compared with CON (all p<0.01). HIIT approaches demonstrated comparable effects to MICT across all parameters. Subgroup analyses suggested that HIIT protocols with low volume (ie, <15 min of high-intensity exercise per session) were not inferior to higher volume protocols for improving MetS components. Conclusion This review supports HIIT as an efficacious exercise strategy for improving cardiometabolic health in individuals with MetS. Low-volume HIIT appears to be a viable alternative to traditional forms of aerobic exercise. The datasets analysed in this review are available from the corresponding author on reasonable request.