Rybka O. The role of insulin-sensitivity in exercise tolerance and cardiometabolic risk development in obese children.

The thesis is devoted to the improvement of methods of diagnosing of cardiometabolic risk in obese children by studying variants of insulin sensitivity and exercise tolerance. Data of assessment of 318 adolescents were assessed. To know the proportion of metabolically healthy obese (MHO) subjects, historical data of 208 overweight and obese adolescents (13.9 + 2.91 y.o.) were analyzed: 31 overweight children, 103 obese children with body mass index (BMI) + 2-3 SD and 74 obese children with BMI +> 3SD. Metabolic syndrome IDF criteria (>3) were used for grouping for metabolically healthy (MHO) and metabolically unhealthy (MUO). 45 adolescents with normal and excessive body mass were additionally involved in the nutrition survey. Physical activity readiness was evaluated according to the recommendations of NHANES, 2014. To assess the exercise tolerance the treadmill test (Bruce protocol) was provided by the recommendations of the American Cardiology Association. Style of nutrition of modern population children reflects a tendency to overweight and dehydration due to imbalanced diet, not planned meals and insufficient support of healthy eating by parents. Overweighs are more prone to consume dairy (more than 2 times per day) than meat or fish, less prone to veggies (with exclusion of potato) and prefer to consume fruits instead of main meals as well as skipping breakfasts and lunches (p<0.01 for all). It has been determined that the average glucose and insulin values during the standard loading are low-informative due to high variability over the different phases of the test. There is a similar profile of the glycemic curve in underweight and severely obese subjects. Low insulin variability (less than 200%) together with no decline or with the second peak after 60 min post-load could be considered as markers of diabetic beta-cells impairment in obese subjects. It has been shown that HbA1C measurement is mandatory for all overweight as soon as reflects the deterioration of insulin sensitivity accurately. In addition to this HbA1C is less costly versus OGTT with insulin and glucose measurement at all points. It has been established that MUO adolescents are under the risk of chronotropic insufficiency during the exercise boost. Cardiorespiratory fitness is reduced both in underweight and overweight subjects despite of the same level of daily physical activity. The metabolic equivalent of physical activity is negatively related to BMI and metabolic status and causes less calories burn in overweight comparatively to the normal weight and underweight during the same exercise load. It has been shown that the violation of whole body insulin sensitivity (mainly due to peripheral one) is directly related to the efficiency of calorie burning during physical activity as well as to the cardiovascular exercise tolerance. All together it could be considered as a potential cardiovascular risk predictor. The level of daily physical activity may well be recognized as the most significant factor for increasing insulin sensitivity and cardiovascular fitness effectiveness in overweight adolescents.