title: Anthropometrics, Physical Performance, and Injury Characteristics of Youth American Football.
abstract: BACKGROUND
  Prior research has described the anthropometric and physical performance characteristics of professional, collegiate, and high school American football players. Yet, little research has described these factors in American youth football and their potential relationship with injury.
  
  
  OBJECTIVE
  To characterize anthropometric and physical performance measures, describe the epidemiology of injury, and examine the association of physical performance measures with injury among children participating within age-based divisions of a large metropolitan American youth football league.
  
  
  METHODS
  Case-control study; Level of evidence, 3.
  
  
  METHODS
  Demographic, anthropometric, and physical performance characteristics and injuries of 819 male children were collected over a 2-year period (2011-2012). Injury data were collected by the league athletic trainer (AT) and coaches. Descriptive analysis of demographic, anthropometric, and physical performance measures (40-yard sprint, pro-agility, push-ups, and vertical jump) were conducted. Incidence rates were computed for all reported injuries; rates were calculated as the number of injuries per 1000 athlete-exposures (AEs). Multinomial logistic regression was used to identify whether the categories of no injury, no-time-loss (NTL) injury, and time-loss (TL) injury were associated with physical performance measures.
  
  
  RESULTS
  Of the 819 original participants, 760 (92.8%) completed preseason anthropometric measures (mean ± SD: age, 11.8 ± 1.2 years; height, 157.4 ± 10.7 cm; weight, 48.7 ± 13.3 kg; experience, 2.0 ± 1.8 years); 640 (78.1%) players completed physical performance measures. The mean (±SD) 40-yard sprint and pro-agility measures of the players were 6.5 ± 0.6 and 5.7 ± 0.5 seconds, respectively; the number of push-ups and maximal vertical jump height were 16.5 ± 9.3 repetitions and 42.3 ± 8.4 cm, respectively. Players assigned to different teams within age divisions demonstrated no differences in anthropometric measures; 40-yard dash and pro-agility times differed significantly (P < .05) between players assigned to different teams. A total of 261 NTL and TL injuries were reported during 35,957 AEs (games: 22%, n = 7982 AEs; practices: 78%, n = 27,975 AEs). The overall incidence rate was 7.26 per 1000 AEs (95% CI, 6.37-8.14). Physical performance measures did not predict NTL or TL injuries (P > .05).
  
  
  CONCLUSIONS
  No practically meaningful differences existed in anthropometric or physical performance measures between teams within age-based levels of play. Findings suggest that age-only criterion for player groupings can evenly match in terms of physical performance.
authors: Sports Medicine Assessment, Research & Testing (SMART) Laboratory, George Mason University, Manassas, Virginia, USA.
authors: Shane V
authors: SV
authors: Caswell
authors: Sports Medicine Assessment, Research & Testing (SMART) Laboratory, George Mason University, Manassas, Virginia, USA.
authors: Ashley
authors: A
authors: Ausborn
authors: Department of Statistics, George Mason University, Fairfax, Virginia, USA.
authors: Guoqing
authors: G
authors: Diao
authors: National Sports Medicine Institute, Lansdowne, Virginia, USA.
authors: David C
authors: DC
authors: Johnson
authors: National Sports Medicine Institute, Lansdowne, Virginia, USA.
authors: Timothy S
authors: TS
authors: Johnson
authors: Sports Medicine Assessment, Research & Testing (SMART) Laboratory, George Mason University, Manassas, Virginia, USA.
authors: Rickie
authors: R
authors: Atkins
authors: Sports Medicine Assessment, Research & Testing (SMART) Laboratory, George Mason University, Manassas, Virginia, USA.
authors: Jatin P
authors: JP
authors: Ambegaonkar
authors: Sports Medicine Assessment, Research & Testing (SMART) Laboratory, George Mason University, Manassas, Virginia, USA.
authors: Nelson
authors: N
authors: Cortes
keywords: injury; physical performance; youth football