Browsing by Author "Riggen, Larry D."

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    Accounting for Variance in Concussion Tolerance Between Individuals: Comparing Head Accelerations Between Concussed and Physically Matched Control Subjects
    Rowson, Steven; Campolettano, Eamon T.; Duma, Stefan M.; Stemper, Brian D.; Shah, Alok S.; Harezlak, Jaroslaw; Riggen, Larry D.; Mihalik, Jason P.; Guskiewicz, Kevin M.; Giza, Christopher C.; Brooks, M. Alison; Cameron, Kenneth L.; McAllister, Thomas W.; Broglio, Steven P.; McCrea, Michael A. (Springer, 2019-10-01)
    Researchers have been collecting head impact data from instrumented football players to characterize the biomechanics of concussion for the past 15 years, yet the link between biomechanical input and clinical outcome is still not well understood. We have previously shown that even though concussive biomechanics might be unremarkable in large datasets of head impacts, the impacts causing injury are of high magnitude for the concussed individuals relative to their impact history. This finding suggests a need to account for differences in tolerance at the individual level. In this study, we identified control subjects for our concussed subjects who demonstrated traits we believed were correlated to factors thought to affect injury tolerance, including height, mass, age, race, and concussion history. A total of 502 college football players were instrumented with helmet-mounted accelerometer arrays and provided complete baseline assessment data, 44 of which sustained a total of 49 concussion. Biomechanical measures quantifying impact frequency and acceleration magnitude were compared between groups. On average, we found that concussed subjects experienced 93.8 more head impacts (p = 0.0031), 10.2 more high magnitude impacts (p = 0.0157), and 1.9 × greater risk-weighted exposure (p = 0.0175) than their physically matched controls. This finding provides further evidence that head impact data need to be considered at the individual level and that cohort wide assessments may be of little value in the context of concussion.
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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
    Stemper, Brian D.; Shah, Alok S.; Harezlak, Jaroslaw; Rowson, Steven; Mihalik, Jason P.; Duma, Stefan M.; Riggen, Larry D.; Brooks, M. Alison; Cameron, Kenneth L.; Campbell, Darren E.; DiFiori, John P.; Giza, Christopher C.; Guskiewicz, Kevin M.; Jackson, Jonathan C.; McGinty, Gerald T.; Svoboda, Steven J.; McAllister, Thomas W.; Broglio, Steven P.; McCrea, Michael A.; Hoy, April Marie Reed; Hazzard, Joseph B.; Kelly, Louise A.; Ortega, Justus D.; Port, Nicholas; Putukian, Margot; Langford, T. Dianne; Tierney, Ryan; Goldman, Joshua T.; Benjamin, Holly J.; Buckley, Thomas; Kaminski, Thomas W.; Clugston, James R.; Schmidt, Julianne D.; Feigenbaum, Luis A.; Eckner, James T.; Guskiewicz, Kevin M.; Miles, Jessica Dysart; Anderson, Scott; Master, Christina L.; Collins, Micky; Kontos, Anthony P.; Bazarian, Jeffrey J.; Chrisman, Sara P. O.; McGinty, Gerald T.; O'Donnell, Patrick; Cameron, Kenneth L.; Susmarski, Adam; Bullers, Christopher Todd; Miles, Christopher M.; Dykhuizen, Brian H.; Lintner, Laura (Springer, 2019-10-01)
    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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    Repetitive Head Impact Exposure in College Football Following an NCAA Rule Change to Eliminate Two-A-Day Preseason Practices: A Study from the NCAA-DoD CARE Consortium
    Stemper, Brian D.; Shah, Alok S.; Harezlak, Jaroslaw; Rowson, Steven; Duma, Stefan M.; Mihalik, Jason P.; Riggen, Larry D.; Brooks, M. Alison; Cameron, Kenneth L.; Giza, Christopher C.; Houston, Megan N.; Jackson, Jonathan C.; Posner, Matthew A.; McGinty, Gerald T.; DiFiori, John P.; Broglio, Steven P.; McAllister, Thomas W.; McCrea, Michael A. (Biomedical Engineering Society, 2019-08-06)
    Repetitive head impact exposure sustained by athletes of contact sports has been hypothesized to be a mechanism for concussion and a possible explanation for the high degree of variability in sport-related concussion biomechanics. In an attempt to limit repetitive head impact exposure during the football preseason, the NCAA eliminated two-a-day practices in 2017, while maintaining the total number of team practice sessions. The objective of this study was to quantify head impact exposure during the preseason and regular season in Division I college football athletes to determine whether the 2017 NCAA ruling decreased head impact exposure. 342 unique athletes from five NCAA Division I Football Bowl Subdivision (FBS) programs were consented and enrolled. Head impacts were recorded using the Head Impact Telemetry (HIT) System during the entire fall preseasons and regular seasons in 2016 and 2017. Despite the elimination of two-a-day practices, the number of preseason contact days increased in 2017, with an increase in average hourly impact exposure (i.e., contact intensity), resulting in a significant increase in total head impact burden (+ 26%) for the 2017 preseason. This finding would indicate that the 2017 NCAA ruling was not effective at reducing the head impact burden during the football preseason. Additionally, athletes sustained a significantly higher number of recorded head impacts per week (+ 40%) during the preseason than the regular season, implicating the preseason as a time of elevated repetitive head impact burden. With increased recognition of a possible association between repetitive head impact exposure and concussion, increased preseason exposure may predispose certain athletes to a higher risk of concussion during the preseason and regular season. Accordingly, efforts at reducing concussion incidence in contact sports should include a reduction in overall head impact exposure.