The role of subconcussive impacts on sway velocities in Division I men's lacrosse players.

Head impacts resulting in a concussion negatively affect the vestibular system, but little is known about the effect of subconcussive impacts on this system. This study's objective was to determine if subconcussive head impacts sustained over one competitive lacrosse season, effect sway velocity. Healthy Division I male lacrosse players (n = 33; aged 19.52 ± 1.20 years) wore instrumented helmets to track head impact exposures. At the beginning and end of the season the players completed an instrumented Balance Error Scoring System assessment to assess sway velocity. Score differentials were correlated to the head impact exposure data collected via instrumented helmets when averaged within participant. Paired samples t-tests revealed a post-season increase in sway velocity on the double leg stance, firm surface (p = 0.002, d = 0.59); tandem stance, firm surface (p = 0.033, d = 0.39) and double leg, foam surface (p = 0.014, d = 0.45) A significant correlation was found between change in tandem stance, firm surface sway velocities and linear acceleration (p < 0.001, r = 0.65). It appears subconcussive impacts may result in tandem stance balance deficits. Repetitive head impacts may negatively affect sway velocity, even in the absence of a diagnosed concussion injury.