Abstract
Physical exercise may activate a number of important biochemical processes in the human body. The aim of this systematic review and meta-analysis was to identify the long-term effect of physical activity on irisin blood levels.
We searched PubMed, Scopus, and Web of Science for articles addressing the long-term effect of physical exercise on irisin blood levels. Fifty-nine articles were included in the final qualitative and quantitative syntheses.
A statistically significant within-group effect of exercise on irisin blood levels was in 33 studies; out of them, the irisin level increased 23x and decreased 10x. The significant positive between-groups effect was found 11x.
Furthermore, the meta-analysis indicated that physical exercise had a significant positive effect on irisin blood levels (SMD = 0.39 (95% CI 0.27-0.52)). Nevertheless, considerably high heterogeneity was found in all the analyses.
This systematic review and meta-analysis indicate that physical exercise might increase irisin blood levels; however, the results of individual studies were considerably inconsistent, which questions the methodological detection of irisin by ELISA kits.