Irisin levels before and after physical activity among school‐age children with different BMI: A direct relation with leptin

Abstract

Objective: Irisin is a novel myokine that seems to mediate the beneficial effects of exercise. Levels of circulating irisin before and after an 8-month physical activity program (PAP) in school-age children were evaluated. Methods: Irisin and leptin were measured at baseline and at follow-up among 85 children with different BMI. Results: Of the 85 children (mean age 8.9; 47% female), 25 children had normal weight, 23 were overweight, and 37 had obesity. We observed no significant difference in irisin serum levels between boys and girls. Irisin was positively associated with BMI before and after the PAP (r before 5 0.42; r after 5 0.37, P < 0.001), with the highest levels in children with obesity. There was a slight decrease of circulating irisin after PAP, but this decrease was not of statistical significance. We observed a high and positive association between irisin and leptin levels before and after the PAP (r before 5 0.78; r after 5 0.82, P < 0.001). Moreover, changes in leptin correlated with changes in irisin (r 5 0.72, P < 0.001). Conclusions: Circulating irisin is positively linked to BMI and leptin in school-age children, supporting the notion that that irisin is produced by adipose tissue. As in previous reports, this study failed to observe changes in irisin levels after exercise, likely because higher irisin levels are produced only during exercise.

Association of Irisin Plasma Levels with Anthropometric Parameters in Children with Underweight, Normal Weight, Overweight, and Obesity

“…Notably, Stengel et al reported lower plasma irisin in anorexic adult patients and a linear relationship between the irisin levels and BMI in adults [8], similar to our finding in children with underweight status. Moreover, a recent study by Palacios-González et al [14] showed higher levels of circulating irisin in obese children and a positive correlation with BMI, also in agreement with our results.…”

“…The underweight group showed the highest proportion of body muscle mass to fat mass, followed by the normal weight, overweight, and obese groups, in this order. The different body composition of each group might account for the variations in the irisin plasma levels, but this relationship remains to be defined for children [14]. …”

“…Few studies have focused on the relationship between irisin and markers of adiposity and physical activity in children [14]. To our knowledge, the present study is the first to examine the association of irisin with anthropometric and physical activity parameters in children with a broad spectrum of BMI percentile statuses.…”

Changes in Thyroid Hormone Levels Within the Normal and/or Subclinical Hyper- or Hypothyroid Range Do Not Affect Circulating Irisin Levels in Humans

“…In addition, previous cross-sectional studies reported associations between irisin and anthropometric or biochemical parameters (10-12), other myokines (13), and adipokines such as adiponectin (14). Studies in children and adolescents have shown that irisin is regulated in a sex-dimorphic manner (15), is positively associated with BMI and leptin (16), and is increased after a 1-year lifestyle intervention program that resulted in significant weight-loss and improvement of other clinical parameters (17). In a longitudinal interventional study, irisin levels were higher in obese children with impaired glucose metabolism and This article has been peer-reviewed and accepted for publication, but has yet to undergo copyediting and proof correction.…”

Brown and Beige Adipose Tissue

“…It seems that irisin is not only a myokine, but it is also an adipokine, 62 and plasma irisin levels are unexpectedly higher in obese humans. 63, 64 Furthermore, Viitasalo and colleagues 65 found a positive and unfavourable correlation between plasma FFAs and irisin in overweight children. More reliable and sensitive detection methods and greater in depth study of the mechanistic regulation of irisin are required to establish whether irisin is indeed a mediator of pathways that propagate obesity, or whether irisin has potential as a therapeutic target for treating or managing obesity.…”