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, I2=0%), TRG (−0.05 (−0.11 to 0.01), p=0.10, I2=0%), LDL-C (0.05 (−0.06 to 0.17), p=0.37, I2=0%), or TC/HDL-C (−0.03 (−0.36 to 0.29), p=0.85, I2=0%). HIIT significantly raised HDL-C (0.07 (0.04 to 0.11), p<0.0001, I2=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.
PROSPERO registration number CRD42019136722.
- exercise training
- exercise intensity
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Contributors GW and NS designed the systematic review and meta-analysis, and performed searches. TvdT reviewed search results. Data extraction was performed by GW and AM. Data validation was performed by GW, AM, NS and TvdT. Data synthesis was performed by GW and AM. The article was written by GW with revisions suggested by AM, NS and TvdT.
Funding GW is supported by an Australian Government Research Training Program (RTP) Scholarship. This work received no other financial support and has no relationship to industry.
Competing interests None declared.
Patient consent for publication Not required.
Ethics approval This systematic review and meta-analysis used pooled data from previously published peer-reviewed articles for which the corresponding ethics approval was obtained by the authors of these previously published studies.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement Data are available on request.
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