Professor emeritus Toivo Jürimäe, PhD, University of Tartu
Assistant Professor Marius Brazaitis, PhD, Lithuanian Sports
Leptin has a permissive role in high energy metabolic processes occurring during puberty. The task of this dissertation is to study possible relationships between leptin, skinfold thicknesses (9) and circumferences (13), peak oxygen consumption, and different levels of physical activity in peripubertal boys with different body mass indices (BMI). As a subjects 248 10-to- 12- year old boys in the first and second study were divided into three BMI subgroups (normal weight, overweight and obese). In the third study boys with normal BMI were selected to the three groups according to leptin levels - average, low and high. Our study confirms that all measured skinfold thicknesses correlate significantly with leptin in all subgroups. In the total and normal BMI groups, the sum of skinfolds is the best parameter to characterize leptin concentration. Circumferences are not the best parameters that characterize body fat mass in the obese group and for this reason no significant correlations with leptin emerged. In our study we used a simple questionnaire for measuring physical activity of different intensity and duration. We studied a subgroups of boys with normal, high and low leptin. In these groups the correlation between leptin and physical activity was weak. Significant correlation emerged only between leptin and regular moderate aerobic physical activity in high leptin subgroup. In our study we found negative correlation between leptin and relative peak oxygen consumption (per kg body weight) in all subgroups.