Two-peak seasonal pattern of injury occurrence among elite u-15 football players

Abstract

Aim: This study aimed to examine intra-seasonal variation in monthly injury incidence, muscle injuries, and injury characteristics across six consecutive competitive seasons in an elite U15 football academy. Particular emphasis was placed on identifying high-risk periods during the training year using exposure-adjusted injury incidence to provide practical recommendations for injury prevention and training periodization. Methods: Injury data were retrospectively collected over six consecutive competitive seasons from elite U15 football players. Overall injuries, muscle injuries, and injury characteristics were recorded according to standardized injury surveillance procedures. Monthly injury frequencies were calculated descriptively, while exposure-adjusted injury incidence was analysed using incidence rate ratios (IRR) with 95% confidence intervals and Poisson regression with a log link function. Differences in the monthly distribution of traumatic and overuse injuries were assessed using the Wilcoxon matched-pairs signed-rank test. Statistical analyses were performed using TIBCO Statistica 14.1.0 and MedCalc software, with the significance level set at p < 0.05. Results: A total of 337 injuries were recorded during the observation period, of which 130 (38.6%) were classified as muscle injuries. Injury occurrence varied considerably throughout the season, with the highest overall injury frequencies observed in September (n = 46), October (n = 48), and February (n = 42). Muscle injuries demonstrated a comparable temporal pattern, peaking in September (n = 22) and April (n = 17). Incidence rate ratios revealed significantly greater injury risk in August (IRR = 1.79), September (IRR = 2.14), October (IRR = 2.33), and February (IRR = 2.18), whereas December exhibited the lowest injury risk (IRR = 0.10; p < 0.001). No significant differences were observed between the monthly distributions of traumatic and overuse injuries (p = 0.31). Conclusions: Injury occurrence in elite U15 football players demonstrates clear seasonal variation, with distinct high-risk periods immediately following the preseason and again during the second half of the competitive season. These findings emphasise the importance of exposure-based injury surveillance and support the implementation of targeted load management, structured strength and conditioning programmes, and injury-prevention strategies during periods of elevated injury risk.