This study describes exposure to repetitive head impacts (RHI) by player position and activity during a collegiate football season, and investigates the relationship between RHI and acute (i.e., daily and weekly) and short-term (i.e., pre- to post-season) changes in balance, reaction time, symptoms, and cognition. We recorded RHI exposure in twenty Division I collegiate American football players during a single season using the Riddell InSite system. Participants sustained 4,586 impacts (4.20% high impact, i.e., >63 g; 95.79% low impact, i.e., 20–63 g). Greatest exposure to RHI was observed in running backs and defensive ends during games, and tight ends and defensive ends during practices. Running plays and team drills placed players at greatest risk for exposure during practice. Cumulative RHI exposure across the season was associated with short-term declines in reaction time (p = 0.045), but not balance or cognition. Acute decline in balance was associated with the number of impacts sustained in the past week (p < 0.05), but not the past 24 hours (p > 0.05). Acute increase in total symptom score was also associated with the number of impacts sustained in the past week (p < 0.01), but not the past 24 hours (p > 0.05). Reaction time did not decline based on impact exposure in the past 24 hours or week. This study identifies activities and positions that may put players at risk for RHI exposure, and demonstrates that RHI sustained during the course of typical American football play by non-concussed individuals may result in small changes in balance, reaction time, and symptoms, but not cognition.

本研究描述了在大学橄榄球赛季期间球员位置和活动对重复性头部撞击 (RHI) 的暴露，并调查了 RHI 与急性（即每天和每周）和短期（即赛季前到后）之间的关系) 平衡、反应时间、症状和认知的变化。我们使用 Riddell InSite 系统在一个赛季中记录了 20 个 I 级大学美式足球运动员的 RHI 暴露情况。参与者承受了 4,586 次冲击（4.20% 高冲击，即 >63 g；95.79% 低冲击，即 20-63 g）。在比赛期间的跑卫和防守端以及练习期间的紧身和防守端观察到 RHI 的最大暴露。跑步比赛和团队训练使球员在练习期间暴露的风险最大。整个季节的累积 RHI 暴露与反应时间的短期下降（p = 0.045）有关，但与平衡或认知无关。平衡的急剧下降与过去一周持续的影响次数有关 (p < 0.05)，但与过去 24 小时无关 (p > 0.05)。总症状评分的急剧增加也与过去一周持续的影响次数有关 (p < 0.01)，但与过去 24 小时无关 (p > 0.05)。反应时间并未因过去 24 小时或一周内的冲击暴露而下降。本研究确定了可能使球员面临 RHI 暴露风险的活动和位置，并表明在典型的美式橄榄球比赛过程中，未受脑震荡的个体持续的 RHI 可能会导致平衡、反应时间和症状的微小变化，但不会认识。