Cytokine Response To Resistance Exercise In Children With Obesity Or Prader-Willi Syndrome

BACKGROUND: Interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-α), and irisin are cytokines that are affected both by adiposity and exercise. Adiposity increases all of these cytokines at rest, while the research is limited on the responses of these cytokines in children to resistance exercise. PURPOSE: To compare IL-6, TNF-α and irisin responses to resistance exercise in children with Prader-Willi Syndrome (PWS), a genetic cause for obesity (OB), vs. children with normal fat mass (LN), or excess body fat (OB). METHODS: Nine children with PWS (11.4 ± 3.3 years, 45.6 ± 5.2% body fat), 11 children with LN (9.2 ± 1.4 years, 18.6 ± 5.0% body fat), and 12 children with OB (9.6 ± 1.3 years, 40.4 ± 5.4% body fat) participated. Children stepped onto an elevated platform wearing a weighted vest for 6 sets of 10 repetitions per leg (sets separated by 1 min of rest). Children with PWS, stepped to a platform height of 23.0 cm and wore a vest load = (20% of stature* 50% of lean body mass)/23.0 cm. For the controls, the platform height was 20% of the stature and the vest load was 50% of the lean body mass. Blood samples were obtained before (pre), immediately post (IP), and during recovery (+15 and + 60 min). Areas under the curve (AUC) were computed for all cytokines. RESULTS: There were no group by time interactions for IL-6, TNF-α or irisin; and no time or group effects for TNF-α or irisin (p ≥ .378 for all). There were time (p < .001) and group effects (p = .011) for IL-6. Pairwise comparisons showed 60+ (1.065 ± 0.10 pg/mL) was higher than pre (0.660 ± 0.05 pg/mL), IP (0.728 ± 0.06 pg/mL), and + 15 (0.764 ± 0.066 pg/mL) for IL-6 (p < .001 for all). Children with PWS and OB had higher IL-6 concentrations than children with LN (0.943 ± 0.12 pg/mL and 0.951 ± 0.10 pg/mL vs. 0.519 ± 0.11 pg/mL, p ≤ .038 for both). Children with PWS or OB showed a higher IL-6 AUC than children with LN (p ≤ .041 for both). There were no significant differences in AUC for TNF-α or irisin (p ≥ .404). CONCLUSION: PWS or excess body fat did not affect IL-6, TNF-α or irisin responses to exercise. However, excess body fat was associated with higher IL-6 concentrations and AUC. Perhaps IL-6 concentrations at IP were not elevated because the protocol was of insufficient intensity or duration. Further studies should examine TNF-α or irisin with a larger sample size or a protocol of longer duration or greater intensity. US Army Medical Research and Material Command Contract W81XWH-08-1-0025