Effect of Repetitive Head Impacts on Saccade Performance in Canadian University Football Players

Abstract

Objective: Investigate the effect of cumulative head impacts on saccade latency and errors, measured across two successive football seasons.

Design: Participants were acquired from a sample of convenience-one Canadian university football team. Head impacts were collected during training camp, practices, eight regular season games, and four playoff games in each season. Saccade measurements were collected at five time points-before and after training camp, at midseason, after regular season, and after playoffs.

Setting: Two seasons following players from a single USports football team during practices and games.

Participants: Players who completed a baseline saccade measurement and a minimum of one follow-up measurement were included in the study. A total of 127 players were monitored across two competitive seasons, including 61 players who participated in both seasons.

Independent variables: Head impact measurements were collected using helmet-mounted sensors.

Main outcome measures: Saccade latency and number of errors were measured using high-speed video or electro-oculography.

Results: On average, each head impact increased prosaccade latency by 5.16 × 10-3 ms (95% confidence interval [CI], 2.26 × 10-4-1.00 × 10-2, P = 0.03) and antisaccade latency by 5.74 × 10-3 ms (95% CI, 7.18 × 10-4-1.06 × 10-2, P = 0.02). These latency increases did not decrease between the two seasons; in fact, prosaccade latencies were 23.20 ms longer (95% CI, 19.40-27.14, P < 0.001) at the second season's baseline measurement than the first. The number of saccade errors was not affected by cumulative head impacts.

Conclusions: Repetitive head impacts in Canadian university football result in cumulative declines in brain function as measured by saccade performance.

Clinical relevance: Football organizations should consider implementing policies focused on reducing head impacts to improve player safety.