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.

Effect of Chronic Resistance Training on Circulating Irisin: Systematic Review and Meta-Analysis of Randomized Controlled Trials

“…No additional studies were identified after verifying the references of the articles included or through other additional sources. Therefore, eight articles [35][36][37][38][39][40][41][42] met the inclusion criteria and were incorporated into the qualitative analysis [40]. Nevertheless, one article ultimately did not present enough data to estimate the effect size [40], so the quantitative synthesis included seven articles [35][36][37][38][39]41,42].…”

“…Although all the interventions proposed similar frequency, training volumes, supervised session percentages and multi-articular exercises, the intensity, the progression in that intensity and the duration of the training schedules differed between the interventions. The intensity of the training was in a range between 55% [39] and 85% [38,41] of 1RM, and five of the eight articles considered the progression in training intensity [37,38,[40][41][42]. Considering the type of exercises performed, most of the trainings were executed using machine-based exercises [35,36,38,[40][41][42], while the program of Kim et al, 2015 [37] was executed using elastic bands; and that of Ghanbari-Niaki et al [39] was performed in circuit mode, and therefore, the intensity could be affected.…”

“…After assessing the risk of bias, 100% of the included studies showed low risk of bias in the domains of "randomization process", "deviations from the intended interventions", "missing outcome data" and "selection of the reported result". However, the domain related to measuring the outcome presented some concerns in five of them [36][37][38][39][40]. This is because one of the parameters that this domain evaluates is the evaluators data blindness.…”

The Potential Role of Irisin in Vascular Function and Atherosclerosis: A Review

“…Exercise is an effective intervention for both the prevention and the treatment of obesity and insulin resistance because skeletal muscle secretes many bioactive proteins that contribute to the beneficial effect of exercise [ 1 , 2 , 3 ]. Exercise-induced muscle contraction stimulates the gene expression for fibronectin type III domain-containing protein 5 (FNDC5), a membrane protein [ 1 ].…”

Fasting Insulin and Alanine Amino Transferase, but not FGF21, Were Independent Parameters Related with Irisin Increment after Intensive Aerobic Exercising

“…In a pilot study, irisin levels increased by 35% after only 3 min of starting physical activity 21 . Irisin also increased after exercise-induced muscle damage from downhill running 22 , but not with resistance training 23 . Consistently, irisin levels increased after 2 weeks of exercising in our cohort of young women.…”