Objective. The aim of the present meta-analysis was to investigate the effect of different types of exercise training on circulating irisin levels in individuals with metabolic disorders.
Research Methods. A comprehensive search was conducted in PubMed, Web of Science, Scopus, Google Scholar, and Iranian databases without time limits up to December 1403. The inclusion criteria were based on the PICOS guidelines (population, intervention, comparison, outcome, and study design) and included: (1) adults over 18 years of age with metabolic disorders; (2) regular exercise training with an intervention duration of more than 2 weeks; (3) studies with a control group or more than one training group; (4) measurement of irisin in the bloodstream (serum or plasma); and (5) controlled study designs.
Findings. A total of 27 studies including 1204 male and female subjects aged 20–75 years were included in the meta-analysis. The results showed that aerobic exercise (15 interventions, P = 0.09, SMD = 0.422), HIIT (8 interventions, P = 0.001, SMD = 0.981), and combined exercise training (9 interventions, P = 0.036, SMD = 0.391) significantly increased irisin levels. In contrast, resistance training (11 interventions, P = 0.116, SMD = 0.309) did not result in a significant change in irisin levels.
Conclusion. Overall, the results of this meta-analysis indicate that exercise training is an effective intervention for increasing circulating irisin levels in individuals with metabolic disorders. However, the response of irisin to exercise training depends on the type of exercise.