Objective This study aimed to establish a nationwide data collection network in order to identify injury incidence and risk factors during competition in elite youth soccer athletes. We also sought to identify the influence of playing games on consecutive days and the inclusion of a rest day on injury risk in multi-day events.

Design Prospective Cohort Study

Setting Elite Clubs National League (ECNL) events with one game per day over 3 days (regular season, unlimited substitution, no rest days) or 4 days (post-season, limited substitution, rest day between games 1 and 3)

Participants Youth soccer players

Main Outcome Measures Injuries at events were recorded by athletic trainers regarding mechanism, type, body part, return-to-play (yes, no), game number (1-3), and time of year (regular, post-season). Comparisons between groups were made with chi-square tests and the associations of injury incidence with gender, age, game number and time of year were assessed through negative binomial regression models.

Results 806 injuries were reported from 24 events representing 200,047 player-hours. Injury incidence was 4.0 per 1000 player-hours overall and girls had a higher injury incidence than boys (4.4 v 3.5 v per 1,000 player-hours, respectively, incidence rate ratio (IRR)=1.28 [1.0-1.6], p=0.03). Concussion incidence was 0.80 per 1,000 player-hours and did not differ significantly between boys and girls (0.86 v 0.72 per 1,000 player-hours, respectively, IRR=1.28 [0.84-2.0], p=0.26). In the multivariable models, after adjusting for age and gender, injury incidence was not associated with game number (game 2 IRR=0.87 [0.73-1.0], p=0.12; game 3 IRR=0.87 [0.73-1.0], p=0.13). No significant interactions between game number and time of year (rest day or not) were identified for all injuries (Game [3] * Time (regular season) IRR=1.16 [0.65-2.1], p=0.61) or concussions only (1.25 [0.3-5.2], p=0.76).

Conclusions Among this group of elite youth soccer players, girls had a higher overall injury incidence, but concussion incidence was similar. No increased injury incidence was identified during the later games of multi-day events when games were played on consecutive days with unlimited substitution, and injury incidence was not influenced by the inclusion of rest days. The establishment of this novel data collection framework embedded within a nationwide elite youth soccer organization will continue to inform strategies to promote safe and healthy participation in youth soccer events.

Key Points

The incorporation of athletic trainers at youth soccer events represents an opportunity to develop a novel, nationwide data collection network to evaluate match injury characteristics, incidence and risk factors.

Female youth soccer athletes had a higher overall injury incidence, although no difference was identified in injury mechanism, severity, or concussion incidence.

With unlimited substitution, playing 3 full-length games on 3 consecutive days was not associated with an increased injury or concussion incidence in later games, and the incorporation of rest days in multi-day events did not appear to influence injury or concussion risk.

The primary author (AW) serves as the Chief Medical Adviser for the Elite Clubs National League.

This study did not receive any funding

I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.

Yes

The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

All procedures performed in this study were approved by the Institutional Review Board of the University of Wisconsin-Madison.

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I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance).

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I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable.

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All data produced in the present study are available upon reasonable request to the authors