[Myokines in obese adolescents with aerobic exercise].

BACKGROUND: Myokines are synthesized by myocytes and released into the bloodstream in response to muscle fiber contraction. They have a positive effect on carbohydrate and lipid metabolism, muscle mass growth, osteogenesis, increase tissue sensitivity to insulin, counteract inflammation of adipose tissue. The study of their secretion in response to physical activity (FA) can help to personalize the therapy of obesity. AIM: to study the features of the secretion of myokines in children with constitutionally exogenous obesity during physical activity of different duration and intensity and to evaluate their relationship with the parameters of the body composition. MATERIALS AND METHODS: 26 children (10 boys and 16 girls) were included in the study 15 [13; 16] years old, SDS BMI: +2.91 [2.24; 3.29], with sexual development according to Tanner 4-5. Two groups of 13 people were formed by random distribution. Group I performed FA (walking on a treadmill under the control of heart rate) of different duration: 30 and 60 minutes at the same intensity (less than 3 metabolic equivalents (MET)). Group II - FA of different intensity: low - less than 3 METH and moderate - 3-6 METH with the same duration of 45 minutes. Commercial kits for enzyme immunoassay were used to determine the level of myokines. The assessment of the compositional composition of the body was carried out by bioimpedance analysis (analyzer In Body 770, South Korea) in the morning, on an empty stomach. Statistical processing was carried out using STATISTICA v.12.0 (StatSoftInc., USA). The results are presented in the form of median (Me) and quartiles (Q1; Q3) corresponding to 25 and 75 percentiles. The critical significance level (p) was assumed to be <0.05. RESULTS: moderate intensity FA leads to a maximum increase in the level of myokines: interleukin-6 (IL-6) by 215.7% and decorin by 34.3%, a decrease in the level of irisin by 16.5%. An hour-long low-intensity workout leads to a moderate increase in the level of IL-6 by 80.5%, to a decrease in the level of irisin by 31.1%. Myostatin increases equally both after 60-minute FA and after moderate intensity FA by 30.9% and 31.8%, respectively. Short low-intensity FA (lasting 30 minutes) it is not accompanied by a significant increase in the expression of myokines. The relationship between the amount of muscle (r=0.65), lean (r=0.62), fat-free mass (r=0.64) and the level of decorin after FA was noted. There was no statistically significant relationship between the parameters of the body composition and the levels of IL-6, myostatin, and irisin. There were no gender differences in both basal and stimulated myokine secretion. CONCLUSION: Moderate intensity FA and low intensity 60-minute FA are most effective for obese children. A 30-minute low-intensity FN is insufficient to increase the secretion of myokines by skeletal muscles.

[Energy exchange: how we can personalize obesity therapy].

Obesity is a consequence of chronic energy imbalance when energy intake constantly exceeds expenditure, which leads to excess white adipose tissue accumulation. Effective treatment of obesity requires accurate measure of calories intake and expenditure, as well as related behavior to understand how energy homeostasis is regulated and evaluate the effectiveness of the measures taken. The greatest interest is to study features of energy metabolism in various forms of obesity. It is necessary to create an evidence-based, personalized approach to diet therapy and to increase the effectiveness of weight loss measures. Modern studies have shown that the use of indirect calorimetry in obesity treatment programs leads to greater weight loss compared to traditional diet therapy planning based on calculated formulas.

[Myokines and adipomyokines: inflammatory mediators or unique molecules of targeted therapy for obesity?]

Skeletal muscles make up about 25% of the total mass in children and more than 40% in adults. Studies of the last twenty years have shown that along with the main functions, muscle tissue has hormonal activity. It was found that myocytes are able to release signaling molecules-myokines. They act auto-and paracrine within the muscle, and at a high level-through the systemic circulation, carrying out interactions between skeletal muscles and various organs and tissues, such as the liver, bone and adipose tissue, the brain. It is proved that the key factor in the expression of myokines is physical activity, and their level largely depends on physical fitness, the amount of skeletal muscle mass and its composition (the ratio of fast and slow fibers), on the intensity and duration of physical activity. Myokines have a wide range of physiological effects: myostatin suppresses the growth and differentiation of muscle tissue, and decorin, acting as its antagonist, promotes muscle hypertrophy. Interleukin 6 provides an energy substrate for contracting muscle fibers, fibroblast growth factor 21 activates the mechanisms of energy production during fasting and improves tissue sensitivity to insulin; irisin stimulates thermogenesis, glucose uptake by myocytes, and also contributes to an increase in bone mineral density. The study of myokines is one of the key links in understanding the mechanisms underlying obesity and metabolic complications, the consequences of a sedentary lifestyle, as well as the implementation of the action of physical activity. Taking into account the physiological effects of myokines in the body, in the future they can become therapeutic targets for the treatment of these conditions.