Background: This study investigated the impacts of exercise on irisin and fibroblast growth factor 21 (FGF-21) expression, as well as triiodothyronine (T3 ) and free fatty acid (FFA) levels in elderly women.
Methods: Thirty women aged 65 to 70 years (10 per group) were randomly assigned to aquatic exercise, land exercise, and control groups. The aquatic and land groups engaged in 3 exercise sessions per week (60 min/session) for 16 weeks. The intensity was progressively increased every 4 weeks.
Results: Irisin and FGF-21 levels significantly increased in the aquatic exercise group. In the posttest, the aquatic exercise group had the highest irisin levels. Significant findings were observed for irisin and FGF-21 for the main effect between aquatic and band exercise groups (p<0.05 for both), the main effect between measurement times (p<0.01 and p<0.001, respectively), and the interaction effect (p<0.05 and p<0.001, respectively). The irisin level was significantly higher in the aquatic than in the land group 30 minutes after the last session (p<0.05). In both exercise groups, T3 levels were significantly higher 30 minutes after the final session (p<0.05) than before the program. The FFA level was significantly higher in the aquatic exercise group than the others. In the aquatic group, FFA levels were significantly higher 30 minutes after both the first (p<0.01) and the last (p<0.001) session compared to pre-program values.
Conclusion: Differences in exercise type and environment can promote fat metabolism by stimulating hormonal changes that induce brown fat activity and browning.
Keywords: Aquatic exercise; Fibroblast growth factor 21; Free fatty acid; Irisin; Triiodothyronine.