Document Type : Original Article
Authors
1 MSc in Exercise Physiology, Faculty of Educational Sciences and Psychology, University of Mohaghegh Ardabili, Ardabil, Iran.
2 Professor of Exercise Physiology, Faculty of Educational Sciences and Psychology, University of Mohaghegh Ardabili, Ardabil, Iran.
3 Associate Professor of Exercise Physiology, Faculty of Educational Sciences and Psychology, University of Mohaghegh Ardabili, Ardabil, Iran.
Abstract
Introduction: Obesity and overweight are associated with many chronic diseases, including diabetes and increased inflammation. Adipose tissue is an endocrine organ known to be active in controlling body metabolism and is not simply a place for storing energy. It is a complex and highly active endocrine and metabolic organ that is not only responsible for energy production, but also produces and secretes numerous proteins such as leptin, visfatin, resistin, and adiponectin, which are called adipokines. Leptin is an important adipokine that has been of interest to researchers for its role in insulin resistance and possibly in the etiology of diabetes. In addition to its important role in regulating appetite and food intake, this hormone is associated with inflammatory and atherogenic cytokines, platelet aggregation, arterial thrombosis, hypertension, and insulin resistance. IL-6 is defined as a cytokine that is produced and released by contracting skeletal muscle fibers and exerts its effects in other organs of the body. Interleukin-6 increases fat turnover, stimulates lipolysis, and also fat oxidation. This adipokine, which is associated with obesity and insulin resistance, is a multifunctional cytokine that can regulate many cellular and biological processes, such as immune function, cell differentiation, proliferation, apoptosis, etc. Diabetes is associated with subclinical systemic inflammation due to increased plasma levels of pro-inflammatory cytokines such as IL-6 and TNF-α. Given the irreversible consequences of obesity and its prevalence in society due to modern lifestyles, researchers are always looking to discover the best and most efficient treatment for obesity, of which exercise and herbal medicine are one of the methods. Therefore, the aim of this study was to investigate the effect of eight weeks of saffron supplementation along with resistance training on serum leptin, interleukin-6, and insulin levels in overweight men.
Materials and Methods: 40 overweight students were randomly divided into 4 groups: exercise (n=10), exercise + supplement (n=10), supplement (n=10), and control (n=10). The exercise group performed resistance training for 8 weeks, 3 sessions of 90 minutes each week in the evening. Resistance training consisted of 12 exercises in 12 stations including leg press, chest press, incline chest press, seated row, deadlift, bent-knee crunch, overhead pull-up, toe raise, hamstring curl, shoulder press, barbell chin-up, and barbell curl, which were performed based on the principle of overload with rest intervals between stations and sets of 1, 1-2, and 3-5 minutes for very light, light, medium, and heavy intensities, respectively. The training for each exercise was in the very light section (20 repetitions, one set, 40% of one repetition maximum), the light section (15 repetitions, two sets, 60% of one repetition maximum), the medium section (10 repetitions, three sets, 75% of one repetition maximum), and the heavy section (4 repetitions, three sets, 90% of one repetition maximum). The supplement and exercise + supplement groups used saffron tablets at a dose of 30 mg as a supplement. One-way analysis of variance (ANOVA) test along with the LSD post hoc test was used for comparison between groups’ differences and the paired t-test was used to compare pre- test and post-test in each group.
Results and Discussion: The results of the one-way analysis of variance test showed a significant difference in the serum levels of leptin, interleukin-6, glucose insulin and insulin resistance between the research groups (P<0.05). The levels of serum interleukin-6, leptin, and glucose and insulin resistance were significantly lower in the exercise, exercise + supplement and supplement groups compared to the control group. Also, the serum levels of interleukin-6, leptin and glucose in the exercise + supplement group were significantly lower compared to the exercise and supplement groups (P<0.05). The presence of various metabolites in saffron, especially crocin and the carotenoid crocin, and the strong effects of stimulating glucose uptake, reducing insulin resistance through peripheral tissue and inhibiting intestinal glucose absorption are mechanisms involved in improving the function of pancreatic cells and ultimately reducing serum glucose. Exercise increases glucose transport by insulin and the activity of the enzyme hexokinase II. In addition, muscle contractions increase the translocation of glucose transporter type 4 through the AMP-activated protein kinase signaling pathway, but it seems that the gradual increase in muscle mass is among the benefits of resistance training, which leads to glycemic control and increased blood glucose disposal capacity. The results of the present study showed that supplement consumption had no effect on serum leptin levels, but eight weeks of resistance training significantly reduced this index. Regarding the response of leptin to exercise, various studies have concluded that exercise programs that lead to a decrease in fat mass and body weight are mainly associated with a decrease in leptin. In the present study, a decrease in weight, body mass index, and waist-to-hip ratio was observed in the post-test of the exercise and exercise + supplement groups, but not in the supplement group.
Conclusion: It can be concluded from the results of the present study, that eight weeks of saffron supplementation and circuit resistance training both reduce serum levels of interleukin-6, glucose, leptin, insulin and insulin resistance in overweight men. The combination of exercise and saffron supplementation had more beneficial effects on serum levels of glucose, leptin and IL-6 than either of them alone.
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