title: Subconcussive head impact biomechanics: comparing differing offensive schemes.
abstract: OBJECTIVE
  Recent literature suggests that subconcussive impacts may influence cognitive functioning across the life span. These effects are suggested to manifest as functional and possibly structural changes. Head impact biomechanics during American football have been characterized from the high school to professional level, but style of play has not been considered. The aim of this investigation was to quantify and compare head impact frequencies and magnitudes between two different offensive schemes.
  
  
  METHODS
  We investigated the frequencies and magnitudes (linear acceleration [g], rotational acceleration [rad·s], and HITsp) of head impacts sustained by 83 high school football athletes, playing for schools using two different offensive schemes. The two schemes comprised a run-first offense (42 athletes) and a pass-first offense (41 athletes). The Head Impact Telemetry System was used to record head impact measures.
  
  
  RESULTS
  A total of 35,620 impacts were recorded across two seasons. Athletes in the run-first offense sustained an average of 456 head impacts per season (41 practices and 9 games), whereas the pass-first offense athletes sustained an average of 304 head impacts per season (44 practices and 9 games). The pass-first offense, however, sustained significantly higher impact magnitudes (P values < 0.05; 28.56g, 1777.58 rad·s, and 16.24) than the run-first offense (25.67g, 1675.36 rad·s, and 15.48) across a season.
  
  
  CONCLUSIONS
  These data provide a first look at how different offensive strategies may influence head impact exposure in football athletes. In the study population, a run-first offense was associated with more frequent head impacts, of smaller magnitude, than a pass-first offense.
authors.affiliation: School of Kineisology, Neurotrauma Research Laboratory, University of Michigan, Ann Arbor, MI 48109-2013, USA.
authors.forename: Douglas
authors.initials: D
authors.lastname: Martini
authors.forename: James
authors.initials: J
authors.lastname: Eckner
authors.forename: Jeffery
authors.initials: J
authors.lastname: Kutcher
authors.forename: Steven P
authors.initials: SP
authors.lastname: Broglio
mesh_terms: D000054:Acceleration; D000293:Adolescent; D001696:Biomechanical Phenomena; D001924:Brain Concussion / Q000503:physiopathology*; D005538:Football / Q000293:injuries; D016489:Head Injuries, Closed / Q000453:epidemiology* / Q000503:physiopathology; D006260:Head Protective Devices; D006801:Humans; D008824:Michigan / Q000453:epidemiology; D013686:Telemetry; D015599:Trauma Severity Indices