Body composition changes during ontogenesis in youth football

Title: Body composition changes during ontogenesis in youth football Objectives: The aim of the work was to identify and compare changes in body composition during ontogenesis in youth categories in football. Methods: Due to our work, a research group was created, which included 4 different age categories. It was a category U12 - U15. U12 (n = 15), U13 (n = 18), U14 (n = 19), U15 (n = 16). He is a player of an elite Czech club. The selection of probands and age categories was intentional. Body composition measurements were performed with a multi-frequency bioimpedance analyzer (Tanita MC-980MA, Tanita Corporation, Japan). The biological age was estimated as follows. The equations of Mirwald et al. (2002). Y: -9.236+(0.0002708*Leg Length and Sitting height interaction) - (0.001663*Age and Leg Length interaction) (0.007216 Age and Sitting Height interaction) + (0.02292*Weight by Height ratio). The players were divided into two groups according to the degree of maturity (before 1, circa 2 (PHV)). Group 1 included players from (> -1 before PHV) and group 2 - circa PHV (-1, +1). Results: The changes in the basic somatometric indicators - body weight and body height were as follows. Body weight: U12 (38.2 kg), U13 (41.4 kg) + 8%, U14 (46 kg) + 11%, U15 (55.1 kg) + 20%. Body height: U12 (148.4 cm), U13..