Objective To compare head impact exposure (HIE) sustained by youth American football players on days of concussion with prior sessions, and to evaluate concussion resolution with objective assessments.

Design Prospective,observational study.

Setting Youth American football.

Participants Youth American football players (11-14 yr, n=57) who had head impact sensors embedded in their helmets; six were diagnosed with a concussion.

Interventions Over four consecutive seasons, baseline and post-injury concussion assessments were performed and HIE was monitored (Head Impact Telemetry system) for all practice/game sessions.

Outcome measures Baseline/Post-concussion assessments – symptoms, balance, reaction time, neurocognitive function (ImPACT), and oculomotor performance (King-Devick). HIE – location, frequency, and magnitude (linear acceleration [LA] and rotational acceleration [RA]).

Main results For concussive impacts, the average peak LA was 85.9 g (39.7-156.8 g) and average peak RA was 6918rad·sec^-2(4508-8433rad·sec^-2). On average, players sustained 21.3 impacts/session on days of concussion vs. 10.2 in previous sessions. Median LA and RA did not differ on days of concussion when compared to prior sessions (21.9 vs. 20.7 g; 1480 vs. 1485 rad·sec^-2). Average duration for a concussed player to have his assessment values return to baseline and be cleared for play was 32 days (17-53).

Conclusions Considerable variation in magnitude existed between impacts that lead to concussion in this population. Players sustained more head impacts in sessions with a concussion compared to prior sessions. Frequency and magnitude of head impacts on the day of concussion did not correlate with time to recovery. Continued observation of a larger cohort is warranted.

Competing interests None.