摘要：Purpose: The aim of the study was to compare parameters identifying the quality of active mass as a predisposition for performance in elite soccer teams of junior and adolescent categories and also to present distribution of fluids in individual segments, which absents in the literature, with indication of asymmetry and possible muscle imbalance. Material and methods: The screened sample was composed of two elite soccer teams from Czech Republic. The first team (junior team, n = 50, age = 20.04 ± 2.69 years, body height = 180.48 ± 6.52, body mass = 74.78 ± 8.42 kg) was a leader of the junior Czech league (two season, cohort teams). The second team (adolescent team, n = 33, age = 16.15 ± 0.87 years, body height = 177.44 ± 7.65, body mass = 67.55 ± 8.99 kg) was a leader of the Czech soccer league U17 category.Body composition was measured using the bioimpedance method. Results: Total body water demonstrated a significant difference between the monitored groups (p<0.01). Juniors compared to adolescents had significantly higher fat free mass in both absolute and relative values, but significantly higher proportion of fat mass (FM) was detected in younger players (FM = 14.64 ± 2.43 %) in comparison to junior players (FM = 12.15 ± 2.83 %). Segmental analysis showed a higher proportion of muscle mass in the trunk of older players when compared to younger players (p< 0.01). Muscle asymmetry between the dominant and non- dominant leg was significantly higher in younger players (p>0.05). We did not record significant differences in comparison of the upper limbs, but lower limbs revealed significant differences in muscle mass proportion (Junior team: t = 7.319; p< 0.01, Adolescent team: t = 12.087; p< 0.01). Discussions and conclusions: The detected values showed that the active component measured by bioimpedance method should achieve almost 90 % of total body mass in junior elite soccer players and 87 % in adolescent players. The detected asymmetry in fluid distribution in the lower limbs is the effect of maladaptation on the specific load of the soccer players.These differences should be taken into account in the training practice and compensated by the adequate exercises.In terms of practice, the results may be beneficial for fitness coaches, nutrition specialist, team medical staff and other clinical staff in professional soccer
