Disclosures: McCrea reports no relevant financial disclosures. Please see the full study for all other authors’ relevant financial disclosures.
February 02, 2021
3 min read

Concussions, head impact exposure occur most often in football preseason, practices

Disclosures: McCrea reports no relevant financial disclosures. Please see the full study for all other authors’ relevant financial disclosures.
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Concussions and head impact exposure in college football players occurred at a “disproportionately higher” rate during the preseason vs. the regular season and most often happened in practices, not games.

Researchers published the findings in JAMA Neurology.

Total head impact exposure was approximately 84% higher in practices compared with games during the regular season

“Concussion ranks among the most common injuries in football,” the researchers wrote. “Beyond the risks of concussion are growing concerns that repetitive head impact exposure may increase risk for long-term neurologic health problems in football players.”

Michael McCrea, PhD, ABPP, professor of neurosurgery and neurology and director of the brain injury research program at the Medical College of Wisconsin, and colleagues examined the pattern in which concussions occurred, as well as repetitive head impact exposure, across six Division I NCAA football programs in the Concussion Assessment, Research and Education (CARE) Consortium. The researchers included 658 college football players from the CARE Consortium (46.5% of 1,416 eligible players in the CARE Advanced Research Core). McCrea and colleagues outfitted the cohort with the Head Impact Telemetry System, prioritizing them according to level of participation.

The study ran from 2015 through 2019. Outcomes included the rate of diagnosed concussion and head impact exposure.

Over five seasons, 528,684 head impacts in 658 players (all men; mean age, 19.02 years) using the Head Impact Telemetry System during practices or games met quality standards for analysis. Players experienced a median of 415 (interquartile range [IQR], 190-727) recorded head impacts per season, according to the study results.

Additionally, 68 players experienced a diagnosed concussion. Nearly half of those injuries (48.5%) occurred in preseason training, despite this part of the season comprising only 20.8% of the entire football season (0.059 preseason vs. 0.016 regular-season concussions per team per day; mean difference, 0.042; 95% CI, 0.02-0.06).

Total head impact exposure in the preseason happened at twice the rate of the regular season (324.9 vs. 162.4 impacts per team per day; mean difference, 162.6, 95% CI, 110.9-214.3). In each season studied, head impact exposure per athlete occurred most frequently in August during preseason (median, 146 impacts [IQR, 63-247.8]) and least frequently in November (median, 80 impacts [IQR, 35-148]).

McCrea and colleagues found that, over five seasons, 72% of concussions (n = 49; game proportion, 0.28, 95% CI, 0.18-0.4) and 66.9% of head impact exposure (262.4 practice vs. 137.2 game impacts per player; mean difference, 125.3, 95% CI, 110-140.6) happened during practice. During the regular season, total head impact exposure in practices (median, 175 impacts per player per season, IQR, 76-340.5) was 84.2% higher than in games (median, 95 impacts per player per season, IQR, 32-206).

The study conducted by McCrea and colleagues represented, to their knowledge, “the largest ... to date on concussion and [head impact exposure] in instrumented college football players.” The results provided “several important points” for understanding the incidence of concussion and head impact exposure in college football players and for developing strategies to decrease the rates of concussion and head impact exposure in this group, according to the researchers.

“First, concussion incidence and [head impact exposure] are disproportionately higher in the preseason than the regular season. Although preseason training represents only about 20% of the full football season, it accounts for roughly half of all concussions, and [head impact exposure] occurs at twice the proportion of the regular season,” McCrea and colleagues wrote. “Second, although per session [head impact exposure] is higher in games than in practice, the abundance of all concussions (72%) and total [head impact exposure] (67%) occurs during practices, not games.”

However, while there is mounting agreement that decreasing rates of concussion and head impact exposure have “important implications” for increased athlete safety in football, NCAA policies to date have had “a limited effect” in reducing the rate of preseason concussion and head impact exposure, the researchers continued.

“The most effective prevention strategies will require a multidimensional approach that extends beyond singularly focused policy and will require buy-in from all key stakeholders, including sport governing bodies, institutional athletic administration, coaches and athletes themselves. Football practice reform to reduce exposure and risk of concussion will undoubtedly require engagement from coaches, who ultimately design and implement drill-specific practice activities,” McCrea and colleagues wrote. “Our data support the development of robust educational offerings that should be customized to specific audiences, including coaches, athletic administrators and players.”