Browsing by Author "Stemper, Brian D."

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    Association between Preseason/Regular Season Head Impact Exposure and Concussion Incidence in NCAA Football
    (ACSM, 2022-06) Stemper, Brian D.; Harezlak, Jaroslaw; Shah, Alok S.; Rowson, Steven; Mihalik, Jason P.; Riggen, Larry; Duma, Stefan; Pasquina, Paul; Broglio, Steven P.; Mcallister, Thomas W.; Mccrea, Michael A.; CARE Consortium Investigators; Psychiatry, School of Medicine
    Purpose Contact sport athletes are exposed to a unique environment where they sustain repeated head impacts throughout the season and can sustain hundreds of head impacts over a few months. Accordingly, recent studies outlined the role that head impact exposure (HIE) has in concussion biomechanics and in the development of cognitive and brain-based changes. Those studies focused on time-bound effects by quantifying exposure leading up to the concussion, or cognitive changes after a season in which athletes had high HIE. However, HIE may have a more prolonged effect. This study identified associations between HIE and concussion incidence during different periods of the college football fall season. Methods This study included 1120 athlete seasons from six National Collegiate Athletic Association Division I football programs across 5 yr. Athletes were instrumented with the Head Impact Telemetry System to record daily HIE. The analysis quantified associations of preseason/regular season/total season concussion incidence with HIE during those periods. Results Strong associations were identified between HIE and concussion incidence during different periods of the season. Preseason HIE was associated with preseason and total season concussion incidence, and total season HIE was associated with total season concussion incidence. Conclusions These findings demonstrate a prolonged effect of HIE on concussion risk, wherein elevated preseason HIE was associated with higher concussion risk both during the preseason and throughout the entire fall season. This investigation is the first to provide evidence supporting the hypothesis of a relationship between elevated HIE during the college football preseason and a sustained decreased tolerance for concussion throughout that season.
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    Comparison of Head Impact Exposure Between Concussed Football Athletes and Matched Controls: Evidence for a Possible Second Mechanism of Sport-Related Concussion
    (Springer, 2018) Stemper, Brian D.; Shah, Alok S.; Harezlak, Jaroslaw; Rowson, Steven; Mihalik, Jason P.; Duma, Stefan M.; Riggen, Larry D.; Brooks, Alison; Cameron, Kenneth L.; Campbell, Darren; DiFiori, John P.; Giza, Christopher C.; Guskiewicz, Kevin M.; Jackson, Jonathan; McGinty, Gerald T.; Svoboda, Steven J.; McAllister, Thomas W.; Broglio, Steven P.; McCrea, Michael; Psychiatry, School of Medicine
    Studies of football athletes have implicated repetitive head impact exposure in the onset of cognitive and brain structural changes, even in the absence of diagnosed concussion. Those studies imply accumulating damage from successive head impacts reduces tolerance and increases risk for concussion. Support for this premise is that biomechanics of head impacts resulting in concussion are often not remarkable when compared to impacts sustained by athletes without diagnosed concussion. Accordingly, this analysis quantified repetitive head impact exposure in a cohort of 50 concussed NCAA Division I FBS college football athletes compared to controls that were matched for team and position group. The analysis quantified the number of head impacts and risk weighted exposure both on the day of injury and for the season to the date of injury. 43% of concussed athletes had the most severe head impact exposure on the day of injury compared to their matched control group and 46% of concussed athletes had the most severe head impact exposure for the season to the date of injury compared to their matched control group. When accounting for date of injury or season to date of injury, 72% of all concussed athletes had the most or second most severe head impact exposure compared to their matched control group. These trends associating cumulative head impact exposure with concussion onset were stronger for athletes that participated in a greater number of contact activities. For example, 77% of athletes that participated in ten or more days of contact activities had greater head impact exposure than their matched control group. This unique analysis provided further evidence for the role of repetitive head impact exposure as a predisposing factor for the onset of concussion. The clinical implication of these findings supports contemporary trends of limiting head impact exposure for college football athletes during practice activities in an effort to also reduce risk of concussive injury.
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    Opportunities for Prevention of Concussion and Repetitive Head Impact Exposure in College Football Players: A Concussion Assessment, Research, and Education (CARE) Consortium Study
    (American Medical Association, 2021) McCrea, Michael A.; Shah, Alok; Duma, Stefan; Rowson, Steven; Harezlak, Jaroslaw; McAllister, Thomas W.; Broglio, Steven P.; Giza, Christopher C.; Goldman, Joshua; Cameron, Kenneth L.; Houston, Megan N.; McGinty, Gerald; Jackson, Jonathan C.; Guskiewicz, Kevin; Mihalik, Jason P.; Brooks, M. Alison; Pasquina, Paul; Stemper, Brian D.; Psychiatry, School of Medicine
    Importance: Concussion ranks among the most common injuries in football. Beyond the risks of concussion are growing concerns that repetitive head impact exposure (HIE) may increase risk for long-term neurologic health problems in football players. Objective: To investigate the pattern of concussion incidence and HIE across the football season in collegiate football players. Design, setting, and participants: In this observational cohort study conducted from 2015 to 2019 across 6 Division I National Collegiate Athletic Association (NCAA) football programs participating in the Concussion Assessment, Research, and Education (CARE) Consortium, a total of 658 collegiate football players were instrumented with the Head Impact Telemetry (HIT) System (46.5% of 1416 eligible football players enrolled in the CARE Advanced Research Core). Players were prioritized for instrumentation with the HIT System based on their level of participation (ie, starters prioritized over reserves). Exposure: Participation in collegiate football games and practices from 2015 to 2019. Main outcomes and measures: Incidence of diagnosed concussion and HIE from the HIT System. Results: Across 5 seasons, 528 684 head impacts recorded from 658 players (all male, mean age [SD], 19.02 [1.25] years) instrumented with the HIT System during football practices or games met quality standards for analysis. Players sustained a median of 415 (interquartile range [IQR], 190-727) recorded head impacts (ie, impacts) per season. Sixty-eight players sustained a diagnosed concussion. In total, 48.5% of concussions (n = 33) occurred during preseason training, despite preseason representing only 20.8% of the football season (0.059 preseason vs 0.016 regular-season concussions per team per day; mean difference, 0.042; 95% CI, 0.020-0.060; P = .001). Total HIE in the preseason occurred at twice the proportion of the regular season (324.9 vs 162.4 impacts per team per day; mean difference, 162.6; 95% CI, 110.9-214.3; P < .001). Every season, HIE per athlete was highest in August (preseason) (median, 146.0 impacts; IQR, 63.0-247.8) and lowest in November (median, 80.0 impacts; IQR, 35.0-148.0). Over 5 seasons, 72% of concussions (n = 49) (game proportion, 0.28; 95% CI, 0.18-0.40; P < .001) and 66.9% of HIE (262.4 practices vs 137.2 games impacts per player; mean difference, 125.3; 95% CI, 110.0-140.6; P < .001) occurred in practice. Even within the regular season, total HIE in practices (median, 175.0 impacts per player per season; IQR, 76.0-340.5) was 84.2% higher than in games (median, 95.0 impacts per player per season; IQR, 32.0-206.0). Conclusions and relevance: Concussion incidence and HIE among college football players are disproportionately higher in the preseason than regular season, and most concussions and HIE occur during football practices, not games. These data point to a powerful opportunity for policy, education, and other prevention strategies to make the greatest overall reduction in concussion incidence and HIE in college football, particularly during preseason training and football practices throughout the season, without major modification to game play. Strategies to prevent concussion and HIE have important implications to protecting the safety and health of football players at all competitive levels.
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    Role of Repetitive Head Impact Exposure in the Onset of Concussion: Evidence of a Possible Second Mechanism of Concussion for Contact Sports
    (International Research Council on the Biomechanics of Injury, 2018-09) Stemper, Brian D.; Shah, Alok S.; Wild, Alexa; Humm, John R.; Pintar, Frank A.; Broglio, Steven P.; McAllister, Thomas W.; McCrea, Michael; Psychiatry, School of Medicine
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    Similar Concussion Rates in Spring Football and Preseason: Findings From the Concussion Assessment, Research and Education Consortium
    (Allen Press, 2023) Broglio, Steven P.; Perkins, Susan M.; Riggen, Larry; Stemper, Brian D.; Shah, Alok; McAllister, Thomas W.; McCrea, Michael; CARE Consortium Investigators; Biostatistics and Health Data Science, Richard M. Fairbanks School of Public Health
    Context: Increasing attention has been directed toward identifying aspects of football participation for targeted policy change that reduces the concussion risk. Prior researchers evaluated concussion risks during the preseason and regular seasons, leaving the spring season largely unexplored. Design: In this nationally representative observational investigation of 19 National Collegiate Athletic Association Division I collegiate football programs, we assessed concussion rates and head impact exposures during the preseason, regular season, and spring practices from 2014 to 2019. All participating programs recorded the incidence of concussions, and a subset (n = 6) also measured head impact exposures. Results: Analyses by time of year and session type indicated that concussion rates and head impact exposures during all practice sessions and contact practices were higher in the spring and preseason than those in the regular season (P < .05). Concussion rates during the spring season and preseason were statistically similar. Conclusions: We identified comparable concussion risks in the spring season and preseason, highlighting the need for targeted policy interventions to protect athlete health and safety.