Incidental physical activity and circulating irisin levels in the adult population: A systematic review and meta-analysis.

Previous studies have confirmed that irisin is released during and after exercise, a subset of physical activity. However, the association between incidental physical activity, including walking up the stairs or to the bus stop, and irisin levels in adults remains unclear. We investigated the association between incidental physical activity and circulating irisin levels in adults. We searched PubMed and Web of Science databases from inception to March 1, 2023. Studies investigating the association between physical activity (but not exercise) and irisin levels in adults were included. Subgroup and meta-regression analyses were performed to identify the factors that could modify the association between physical activity and irisin. The primary outcome was the standardized mean difference (SMD) in circulating irisin levels between the least and most active groups. Twenty articles were included in this systematic review, totaling 6881 adults. Adults engaging in physical activity showed a higher circulating irisin concentration than inactive counterparts (SMD: 1.56; 95%CI: 1.49, 1.63; I2 = 99.1%). Meta-regression revealed that the SMD between active and inactive adults was lower in women than men. Sporadic physical activity is positively associated with circulating irisin levels in adults. [ABSTRACT FROM AUTHOR]