Aerobic Exercise, Metabolic Syndrome, and Lipid Profiles: Protocol for a Quantitative Review

Background:
We describe two systematic reviews and univariate meta-analyses of randomized controlled trials to estimate the effect size of aerobic exercise training on the standard lipid profile of adults diagnosed with, and free of, metabolic syndrome; and the determination if study or intervention covariates explain change in lipid outcomes.
Methods:
English language searches of online databases from inception to June 2020. Data will be included from (a) randomized controlled trials of sedentary adult humans with intervention and non-exercising control groups of n ≥ 10; (b) an aerobic exercise training intervention duration ≥12 weeks of at least moderate intensity (>40% VO_2MAX); and (c) reporting of pre/post lipid measurements. Subjects with chronic disease (except diabetes mellitus or metabolic syndrome), or pregnant/lactating, or trials testing diet/medication, or resistance/isometric/unconventional training will be excluded.
Results:
We will follow the Preferred Reporting Items for Systematic Reviews and Meta-Analysis statement. Univariate meta-analysis will estimate the effect size of aerobic exercise training on the standard lipid profile, using a random raw mean difference, Knapp-Hartung adjusted, 95% confidence interval, model. Statistical tests and precision and standard error funnel plots will evaluate heterogeneity. Multivariate meta-regression will explore whether study or intervention covariates explain change in lipids. Analyses will be performed in Comprehensive Meta-Analysis 3.0. Study quality will be evaluated using TESTEX.
Conclusion:
We aim to estimate the effect size of aerobic exercise training on the standard lipid profiles of adults with and free of metabolic syndrome, and establish if these changes result in minimal meaningful change to cardiovascular disease risk. We aim to determine if meta-regression covariates might explain change in lipids.