Variaciones longitudinales en la composición corporal y el rendimiento físico durante una temporada en jóvenes futbolistas chilenos

There is a growing interest in optimizing the sports talent development process by identifying and operationalizing relevant performance indicators. The study aimed to analyze the variations in body composition and physical performance of young Chilean soccer players during a season. A longitudinal, analytical, observational study with repeated measures was conducted in a single group without a control group, evaluating 54 young Chilean soccer players (16.1 ± 1.1 years) at four points during the season. Anthropometric and body composition variables were recorded. In addition, sprint (10 m, 20 m, and 30 m), 505 test, horizontal jump, countermovement jump (CMJ), and maximal oxygen consumption (VO2max) using the 30-15IFT intermittent resistance test were recorded. At the end of the preseason, significant decreases were observed in ∑5 perimeters and ∑6 skinfolds (p< 0.01; ES: η²p = 0.75 and 0.26, respectively; Large). Furthermore, the percentage of skeletal muscle mass increases at the end of the season (p<0.05; ES: η²p=0.03; Small). In physical performance, 10-30 m sprint improves at the end of the preseason (p<0.01; TE: η²p=0.80-0.82; Large), and significant progress is also seen in the 20- and 30-m sprints at the end of the season. Additionally, VO2max increases in the preseason and mid-2025 measurements (p<0.05; ES: η²p=0.45; Large). The study concludes that, in young Chilean soccer players, a competitive season is associated with relevant changes in body composition and physical performance, with improvements beginning at the end of the preseason and persisting throughout the season.