The effect of exercise training on serum Omentin-1 levels, glycemic control and body composition in adults population: a systematic review and meta-analysis of randomized controlled trials

Background Omentin-1 has been acknowledged as an anti-inflammatory and insulin-sensitizing marker, which is mainly expressed in adipose tissue. Exercise training is a therapeutic intervention that can possibly improve and modify circulating Omentin-1 levels. Objective To determine the effects of exercise training on circulating Omentin-1, glycemic control, and body composition in adult population. Data sources Four electronic databases and reference lists of included articles were searched until February 5, 2023. The effect size of outcomes was summarized by calculating the mean difference (MD) with 95% confidence interval (CI). Results Ten RCTs comprising 385 participants were included. The overall model revealed that exercise training increased Omentin-1 compared to the control (MD = 3.57 ng.ml; 95% CI, 1.80 to 5.34 ng.ml; p < 0.001). Subgroup analysis by exercise modalities revealed significant increases in Omentin-1 after isolated aerobic ( p = 0.002) and resistance ( p < 0.001) training but not after combined training. Subgroup analysis by sex indicated a significant improvement of Omentin-1 in women ( p = 0.015) and men ( p = 0.007). Furthermore, a significant increase was found in both healthy ( p = 0.035) and non-healthy ( p = 0.002) participants. Analysis of other outcomes indicated that exercise training significantly reduced glucose, insulin, insulin resistance, body weight, body mass index, and body fat, as well as improved lipid profiles. Conclusion These findings reveal that isolated aerobic and resistance exercises resulted in an increase in serum levels of Omentin-1 in adults. More high-quality studies are required to clarify the mechanisms underlying the influence of exercise training on Omentin-1 concentrations.