title: Concussions are associated with decreased batting performance among Major League Baseball players.
abstract: BACKGROUND
  Concussions impair balance, visual acuity, and reaction time--all of which are required for high-level batting performance--but the effects of concussion on batting performance have not been reported. The authors examined this relationship between concussion and batting performance among Major League Baseball (MLB) players.
  
  
  OBJECTIVE
  Batting performance among concussed MLB players will be worse upon return to play than batting performance among players missing time for noninjury reasons.
  
  
  METHODS
  Cohort study; Level of evidence, 3.
  
  
  METHODS
  The authors identified MLB players who sustained a concussion between 2007 and 2013 through league disabled-list records and a Baseball Prospectus database. For a comparison group, they identified players who went on paternity or bereavement leave during the same period. Using repeated-measures generalized linear models, the authors compared 7 batting metrics between the 2 groups for the 2 weeks upon return, as well as 4 to 6 weeks after return, controlling for pre-leave batting metrics, number of days missed, and position.
  
  
  RESULTS
  The authors identified 66 concussions and 68 episodes of bereavement/paternity leave to include in the analysis. In the 2 weeks after return, batting average (.235 vs .266), on-base percentage (.294 vs .326), slugging percentage (.361 vs .423), and on-base plus slugging (.650 vs .749) were significantly lower among concussed players relative to the bereavement/paternity leave players (time×group interaction, P<.05). In weeks 4 to 6 after leave, these metrics were slightly lower in concussed players but not statistically significantly so.
  
  
  CONCLUSIONS
  Although concussed players may be asymptomatic upon return to play, the residual effects of concussion on the skills required for batting may still be present. Further work is needed to clarify the mechanism through which batting performance after concussion is adversely affected and to identify better measures to use for return-to-play decisions.
authors.affiliation: Department of Public Health Sciences, University of Rochester School of Medicine and Dentistry, Rochester, New York, USA Department of Emergency Medicine, University of Rochester School of Medicine and Dentistry, Rochester, New York, USA erin_wasserman@urmc.rochester.edu.
authors.forename: Erin B
authors.initials: EB
authors.lastname: Wasserman
authors.affiliation: Department of Public Health Sciences, University of Rochester School of Medicine and Dentistry, Rochester, New York, USA Department of Emergency Medicine, University of Rochester School of Medicine and Dentistry, Rochester, New York, USA.
authors.forename: Beau
authors.initials: B
authors.lastname: Abar
authors.affiliation: Department of Public Health Sciences, University of Rochester School of Medicine and Dentistry, Rochester, New York, USA Department of Emergency Medicine, University of Rochester School of Medicine and Dentistry, Rochester, New York, USA Division of Geriatrics, Department of Medicine, University of Rochester School of Medicine and Dentistry, Rochester, New York, USA.
authors.forename: Manish N
authors.initials: MN
authors.lastname: Shah
authors.affiliation: Department of Public Health Sciences, University of Rochester School of Medicine and Dentistry, Rochester, New York, USA Department of Emergency Medicine, University of Rochester School of Medicine and Dentistry, Rochester, New York, USA Division of Geriatrics, Department of Medicine, University of Rochester School of Medicine and Dentistry, Rochester, New York, USA Department of Physical Medicine & Rehabilitation, University of Rochester School of Medicine and Dentistry, Rochester, New York, USA Department of Neurology, University of Rochester School of Medicine and Dentistry, Rochester, New York, USA Department of Neurosurgery, University of Rochester School of Medicine and Dentistry, Rochester, New York, USAD.W. performed this work on his own time independent of any affiliation.Investigation performed at the University of Rochester School of Medicine and Dentistry, Rochester, New York, USA.
authors.forename: Daniel
authors.initials: D
authors.lastname: Wasserman
authors.affiliation: Department of Public Health Sciences, University of Rochester School of Medicine and Dentistry, Rochester, New York, USA Department of Emergency Medicine, University of Rochester School of Medicine and Dentistry, Rochester, New York, USA Department of Physical Medicine & Rehabilitation, University of Rochester School of Medicine and Dentistry, Rochester, New York, USA Department of Neurology, University of Rochester School of Medicine and Dentistry, Rochester, New York, USA Department of Neurosurgery, University of Rochester School of Medicine and Dentistry, Rochester, New York, USA.
authors.forename: Jeffrey J
authors.initials: JJ
authors.lastname: Bazarian
mesh_terms: D054874:Athletic Performance / Q000502:physiology*; D001484:Baseball / Q000293:injuries* / Q000502:physiology; D001924:Brain Concussion / Q000453:epidemiology* / Q000209:etiology; D015331:Cohort Studies; D006801:Humans; D008297:Male; D011930:Reaction Time / Q000502:physiology*; D012189:Retrospective Studies
keywords: baseball/softball; epidemiology; head injuries/concussion; proprioception/balance