title: Estimating Contact Exposure in Football Using the Head Impact Exposure Estimate.
abstract: Over the past decade, there has been significant debate regarding the effect of cumulative subconcussive head impacts on short and long-term neurological impairment. This debate remains unresolved, because valid epidemiological estimates of athletes' total contact exposure are lacking. We present a measure to estimate the total hours of contact exposure in football over the majority of an athlete's lifespan. Through a structured oral interview, former football players provided information related to primary position played and participation in games and practice contacts during the pre-season, regular season, and post-season of each year of their high school, college, and professional football careers. Spring football for college was also included. We calculated contact exposure estimates for 64 former football players (n = 32 college football only, n = 32 professional and college football). The head impact exposure estimate (HIEE) discriminated between individuals who stopped after college football, and individuals who played professional football (p < 0.001). The HIEE measure was independent of concussion history (p = 0.82). Estimating total hours of contact exposure may allow for the detection of differences between individuals with variation in subconcussive impacts, regardless of concussion history. This measure is valuable for the surveillance of subconcussive impacts and their associated potential negative effects.
authors.affiliation: 1 The Datalys Center for Sports Injury Research and Prevention, Indianapolis Indiana.|2 Matthew Gfeller Sport-Related Traumatic Brain Injury Research Center, University of North Carolina , Chapel Hill, North Carolina.|3 Center for the Study of Retired Athletes, Department of Exercise and Sport Science, University of North Carolina , Chapel Hill, North Carolina.|6 Injury Prevention Center, Department of Epidemiology, University of North Carolina , Chapel Hill, North Carolina.
authors.forename: Zachary Y
authors.initials: ZY
authors.lastname: Kerr
authors.affiliation: 2 Matthew Gfeller Sport-Related Traumatic Brain Injury Research Center, University of North Carolina , Chapel Hill, North Carolina.
authors.forename: Ashley C
authors.initials: AC
authors.lastname: Littleton
authors.affiliation: 3 Center for the Study of Retired Athletes, Department of Exercise and Sport Science, University of North Carolina , Chapel Hill, North Carolina.
authors.forename: Leah M
authors.initials: LM
authors.lastname: Cox
authors.affiliation: 3 Center for the Study of Retired Athletes, Department of Exercise and Sport Science, University of North Carolina , Chapel Hill, North Carolina.
authors.forename: J D
authors.initials: JD
authors.lastname: DeFreese
authors.affiliation: 3 Center for the Study of Retired Athletes, Department of Exercise and Sport Science, University of North Carolina , Chapel Hill, North Carolina.|4 Department of Psychology, University of North Carolina , Chapel Hill, North Carolina.
authors.forename: Eleanna
authors.initials: E
authors.lastname: Varangis
authors.affiliation: 2 Matthew Gfeller Sport-Related Traumatic Brain Injury Research Center, University of North Carolina , Chapel Hill, North Carolina.
authors.forename: Robert C
authors.initials: RC
authors.lastname: Lynall
authors.affiliation: 5 Department of Kinesiology, The University of Georgia , Athens, Georgia .
authors.forename: Julianne D
authors.initials: JD
authors.lastname: Schmidt
authors.affiliation: 2 Matthew Gfeller Sport-Related Traumatic Brain Injury Research Center, University of North Carolina , Chapel Hill, North Carolina.|3 Center for the Study of Retired Athletes, Department of Exercise and Sport Science, University of North Carolina , Chapel Hill, North Carolina.|6 Injury Prevention Center, Department of Epidemiology, University of North Carolina , Chapel Hill, North Carolina.
authors.forename: Stephen W
authors.initials: SW
authors.lastname: Marshall
authors.affiliation: 2 Matthew Gfeller Sport-Related Traumatic Brain Injury Research Center, University of North Carolina , Chapel Hill, North Carolina.|3 Center for the Study of Retired Athletes, Department of Exercise and Sport Science, University of North Carolina , Chapel Hill, North Carolina.
authors.forename: Kevin M
authors.initials: KM
authors.lastname: Guskiewicz
mesh_terms: D000328:Adult; D056352:Athletes; D001265:Athletic Injuries / Q000175:diagnosis*; D001924:Brain Concussion / Q000175:diagnosis*; D005538:Football; D016489:Head Injuries, Closed / Q000175:diagnosis*; D006260:Head Protective Devices; D006801:Humans; D015601:Injury Severity Score; D008297:Male; D055815:Young Adult
keywords: subconcussive impacts; traumatic brain injury