title: Strength and jump biomechanics of elite and recreational female youth soccer players.
abstract: BACKGROUND
  Most researchers investigating soccer injuries have studied elite athletes because they have greater athletic-exposure hours than other athletes, but most youth participate at the recreational level. If risk factors for injury vary by soccer level, then recommendations  generated using research with elite youth soccer players might not generalize to recreational players.
  
  
  OBJECTIVE
  To examine injury risk factors of strength and jump biomechanics by soccer level in female youth athletes and to determine whether research recommendations based  on elite youth athletes could be generalized to recreational players.
  
  
  METHODS
  Cross-sectional study.
  
  
  METHODS
  Seattle Youth Soccer Association.
  
  
  METHODS
  Female soccer players  (N = 92) aged 11 to 14 years were recruited from 4 randomly selected elite (n = 50; age = 12.5 years, 95% confidence interval [95% CI]) = 12.3, 12.8 years; height = 157.8 cm, 95% CI = 155.2, 160.3 cm; mass = 49.9 kg, 95% CI = 47.3, 52.6 kg) and 4 randomly selected recreational (n = 42; age  = 13.2 years, 95% CI = 13.0, 13.5 years; height = 161.1 cm, 95% CI = 159.2, 163.1 cm; mass = 50.6 kg, 95% CI = 48.3, 53.0 kg) soccer teams.
  
  
  METHODS
  Players completed a questionnaire about demographics, history of previous injury,  and soccer experience. Physical therapists used dynamometry to measure hip strength (abduction, adduction, extension, flexion) and knee strength (flexion, extension) and Sportsmetrics to measure vertical jump height and jump biomechanics. We compared all measurements by soccer level using  linear regression to adjust for age and mass.
  
  
  RESULTS
  Elite players were similar to recreational players in all measures of hip and knee strength, vertical jump height, and normalized knee separation (a valgus estimate generated using Sportsmetrics).
  
  
  CONCLUSIONS
  Female elite youth players and recreational players had similar lower extremity strength and jump biomechanics. This suggests that recommendations generated from research with elite youth soccer players could be generalized to recreational players.
authors.affiliation: Department of Pediatrics, University of Washington School of Medicine, Suite 500/MPW 8-1, Box 35900, 1100 Olive Way, Seattle, WA 98101, USA. sdow@u.washington.edu
authors.forename: Sara P
authors.initials: SP
authors.lastname: Chrisman
authors.forename: John W
authors.initials: JW
authors.lastname: O'Kane
authors.forename: Nayak L
authors.initials: NL
authors.lastname: Polissar
authors.forename: Allan F
authors.initials: AF
authors.lastname: Tencer
authors.forename: Christopher D
authors.initials: CD
authors.lastname: Mack
authors.forename: Marni R
authors.initials: MR
authors.lastname: Levy
authors.forename: Melissa A
authors.initials: MA
authors.lastname: Schiff
mesh_terms: D000293:Adolescent; D056352:Athletes; D001265:Athletic Injuries; D001696:Biomechanical Phenomena / Q000502:physiology*; D002648:Child; D003430:Cross-Sectional Studies; D005080:Exercise Test; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000502:physiology; D009043:Motor Activity / Q000502:physiology*; D053580:Muscle Strength / Q000502:physiology*; D018482:Muscle, Skeletal / Q000293:injuries; D012307:Risk Factors; D012916:Soccer / Q000293:injuries*; D013177:Sports; D011795:Surveys and Questionnaires