Plasma irisin is increased following 12 weeks of Nordic walking and associates with glucose homoeostasis in overweight/obese men with impaired glucose regulation

Abstract

Irisin is a myokine that is thought to be secreted in response to exercise that may help to prevent obesity and maintain normal glucose metabolism. In this study we investigated the associations between irisin and glucose homeostasis in middle-aged, overweight and obese men (n =  144) with impaired glucose regulation, and the impact of exercise training on these relationships. The participants underwent 12 weeks of resistance or aerobic (Nordic walking) exercise training three times per week, 60 minutes per session. Venous blood (n = 105) and skeletal muscle samples (n = 45) were obtained at baseline and post-intervention. Compared to controls, Nordic walking, but not resistance training, increased irisin levels in plasma (9.6 ± 4.2%, P = 0.014; 8.7 ±  4.9%, P = 0.087; respectively) compared to controls. When considering all subjects, baseline irisin correlated positively with atherogenic index of plasma (r = 0.244, P = 0.013) and 2-hour insulin levels (r = 0.214, P = 0.028), and negatively with age (r = −0.262, P = 0.007), adiponectin (r = −0.240, P = 0.014) and McAuley index (r = −0.259, P = 0.008). Training-induced FNDC5 mRNA changes were negatively correlated with HbA1c (r = −0.527, P = 0.030) in the resistance training group and with chemerin in the Nordic walking group (r = −0.615, P = 0.033). In conclusion, 12-weeks of Nordic walking was more effective than resistance training in elevating plasma irisin, in middle-aged men with impaired glucose tolerance. Thus, the change in irisin in response to exercise training varied by the type of exercise but showed limited association with improvements in glucose homeostasis.

Keywords:

• Training
• metabolism
• obesity

Acknowledgments

The study was supported by grants from the Research Council for Physical Education and Sports, of the Finnish Ministry of Education, Turku University of Applied Sciences R&D program, Research Foundation for Physiological Treatments and the COST Action CA16112, and Fulbright-Saastamoinen Foundation Grant in Health and Environmental Sciences (KCD).

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by Turku University of Applied Sciences R&D program (Grant no. ISRCTN97931118); Research Council for Physical Education and Sports, of the Finnish Ministry of Education (Grant no. 100/627/2007); Research Foundation for Physiological Treatments (Grant no. 01.08.2014/001) and Fulbright-Saastamoinen Foundation Grant in Health and Environmental Sciences (KCD).