Hiit Is Not Superior To Mict In Altering Blood Lipids: A Systematic Review And Meta-Analysis

Objective To compare the effects of moderate intensity continuous training (MICT) and high intensity interval training (HIIT) on adult lipid profiles; to identify training or participant characteristics that may determine exercise-induced change in total cholesterol (TC), triglycerides (TRG), high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C).Design Systematic review and meta-analysis.Data sources English language searches of several databases were conducted from inception until September 2019.Eligibility criteria for excluding studies Inclusion: (1) published randomised controlled human trials with group population n=5; (2) intervention duration =4 weeks; (3) comparing HIIT with MICT; and (4) reporting pre-post intervention lipid measurements. Exclusion: subjects with chronic disease, <18 years, pregnant/lactating, in elite athletic training; and studies with a dietary or pharmaceutical intervention component.Results Twenty-nine data sets (mmol/L) of 823 participants were pooled and analysed. Neither HIIT nor MICT was better in decreasing TC (0.10 (-0.06 to 0.19), p=0.12, I-2=0%), TRG (-0.05 (-0.11 to 0.01), p=0.10, I-2=0%), LDL-C (0.05 (-0.06 to 0.17), p=0.37, I-2=0%), or TC/HDL-C (-0.03 (-0.36 to 0.29), p=0.85, I-2=0%). HIIT significantly raised HDL-C (0.07 (0.04 to 0.11), p<0.0001, I-2=0%) compared with MICT.Conclusion Neither HIIT nor MICT is superior for altering TC, TRG, or LDL-C, or TC-HDL-C ratio. Compared with MICT, HIIT appeared to significantly improve HDL-C. Clinicians may prescribe either protocol to encourage participation in exercise and reduce cardiovascular risk. To raise HDL-C, HIIT may result in a larger effect size compared with MICT.