Relative age, biological maturation, body composition, and physical performance in under-16 academy soccer players: differences and associations among early and late born athletes.

Purpose: To examine the differences in body composition and physical performance in academy under-16 (U16) soccer players, born in the first (i.e., early born, EB) and second semester (i.e., late born, LB) of the year; and analyze the associations of relative age (RA) and biological maturation (peak height velocity [PHV]) with body composition and physical performance. Methods: Twenty U16 male players (age: 15.6 ± 0.4 years, body mass: 63.7 ± 6.4 kg, height: 172.1 ± 6.3 cm) participated in the study. Body composition, one-repetition maximum in the squat (SQ-1RM) and bench press (BP-1RM), jumps, sprints (linear, curved and change of direction) and endurance capacity tests were completed. Results: EB had a significant earlier maturity offset and higher muscle mass (p < 0.05; ES: 0.91 and 0.94), and performed better in the strength, jump, sprints, and aerobic tests when compared to LB players (p < 0.05; ES varying between 0.89 and 1.41). Significant associations were observed between maturity offset and RA, body composition, and several physical capacities (p < 0.05; r = 0.447 to 0.759). Conclusions: EB players outperformed their LB peers, which may be attributed to their more advanced biological maturation. In addition, maturity offset and RA were both associated to body composition and physical performance metrics in U16 male soccer players. [ABSTRACT FROM AUTHOR]