title: Injury Rates in Age-Only Versus Age-and-Weight Playing Standard Conditions in American Youth Football.
abstract: BACKGROUND
  American youth football leagues are typically structured using either age-only (AO) or age-and-weight (AW) playing standard conditions. These playing standard conditions group players by age in the former condition and by a combination of age and weight in the latter condition. However, no study has systematically compared injury risk between these 2 playing standards.
  
  
  OBJECTIVE
  To compare injury rates between youth tackle football players in the AO and AW playing standard conditions.
  
  
  METHODS
  Cohort study; Level of evidence, 2.
  
  
  METHODS
  Athletic trainers evaluated and recorded injuries at each practice and game during the 2012 and 2013 football seasons. Players (age, 5-14 years) were drawn from 13 recreational leagues across 6 states. The sample included 4092 athlete-seasons (AW, 2065; AO, 2027) from 210 teams (AW, 106; O, 104). Injury rate ratios (RRs) with 95% CIs were used to compare the playing standard conditions. Multivariate Poisson regression was used to estimate RRs adjusted for residual effects of age and clustering by team and league. There were 4 endpoints of interest: (1) any injury, (2) non-time loss (NTL) injuries only, (3) time loss (TL) injuries only, and (4) concussions only.
  
  
  RESULTS
  Over 2 seasons, the cohort accumulated 1475 injuries and 142,536 athlete-exposures (AEs). The most common injuries were contusions (34.4%), ligament sprains (16.3%), concussions (9.6%), and muscle strains (7.8%). The overall injury rate for both playing standard conditions combined was 10.3 per 1000 AEs (95% CI, 9.8-10.9). The TL injury, NTL injury, and concussion rates in both playing standard conditions combined were 3.1, 7.2, and 1.0 per 1000 AEs, respectively. In multivariate Poisson regression models controlling for age, team, and league, no differences were found between playing standard conditions in the overall injury rate (RRoverall, 1.1; 95% CI, 0.4-2.6). Rates for the other 3 endpoints were also similar (RRNTL, 1.1 [95% CI, 0.4-3.0]; RRTL, 0.9 [95% CI, 0.4-1.9]; RRconcussion, 0.6 [95% CI, 0.3-1.4]).
  
  
  CONCLUSIONS
  For the injury endpoints examined in this study, the injury rates were similar in the AO and AW playing standards. Future research should examine other policies, rules, and behavioral factors that may affect injury risk within youth football.
authors.affiliation: Datalys Center for Sports Injury Research and Prevention Inc, Indianapolis, Indiana, USA.
authors.forename: Zachary Y
authors.initials: ZY
authors.lastname: Kerr
authors.affiliation: University of North Carolina, Chapel Hill, North Carolina, USA.
authors.forename: Stephen W
authors.initials: SW
authors.lastname: Marshall
authors.affiliation: University of Toledo, Toledo, Ohio, USA.
authors.forename: Janet E
authors.initials: JE
authors.lastname: Simon
authors.affiliation: Datalys Center for Sports Injury Research and Prevention Inc, Indianapolis, Indiana, USA.
authors.forename: Ross
authors.initials: R
authors.lastname: Hayden
authors.affiliation: Datalys Center for Sports Injury Research and Prevention Inc, Indianapolis, Indiana, USA.
authors.forename: Erin M
authors.initials: EM
authors.lastname: Snook
authors.affiliation: Springfield College, Springfield, Massachusetts, USA.
authors.forename: Thomas
authors.initials: T
authors.lastname: Dodge
authors.affiliation: Salem State University, Salem, Massachusetts, USA.
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Gallo
authors.affiliation: AT Still University, Mesa, Arizona, USA.
authors.forename: Tamara C
authors.initials: TC
authors.lastname: Valovich McLeod
authors.affiliation: University of South Carolina, Columbia, South Carolina, USA.
authors.forename: James
authors.initials: J
authors.lastname: Mensch
authors.affiliation: Charleston Southern University, Charleston, South Carolina, USA.
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Murphy
authors.affiliation: St Vincent Sports Performance, Indianapolis, Indiana, USA.
authors.forename: Vincent C
authors.initials: VC
authors.lastname: Nittoli
authors.affiliation: Datalys Center for Sports Injury Research and Prevention Inc, Indianapolis, Indiana, USA.
authors.forename: Thomas P
authors.initials: TP
authors.lastname: Dompier
authors.affiliation: Datalys Center for Sports Injury Research and Prevention Inc, Indianapolis, Indiana, USA.
authors.forename: Brian
authors.initials: B
authors.lastname: Ragan
authors.affiliation: Datalys Center for Sports Injury Research and Prevention Inc, Indianapolis, Indiana, USA.
authors.forename: Susan W
authors.initials: SW
authors.lastname: Yeargin
authors.affiliation: Datalys Center for Sports Injury Research and Prevention Inc, Indianapolis, Indiana, USA.
authors.forename: John T
authors.initials: JT
authors.lastname: Parsons
keywords: epidemiology; injury risk; youth football