title: Preparticipation physical examination using a box drop vertical jump test in young athletes: the effects of puberty and sex.
abstract: OBJECTIVE
  Neuromuscular performance increases rapidly in males throughout pubertal development, whereas no similar neuromuscular spurt occurs in females. This fact may underlie neuromuscular imbalances related to increased risk of injury in females. The hypothesis: female athletes would demonstrate mismatched landing force to power production compared with males.
  
  
  METHODS
  This study used a cross-sectional study design to compare cohorts of pubertal stage-matched males and females during preparticipation physical examination.
  
  
  METHODS
  An onsite preparticipation physical examination at a Texas High School.
  
  
  METHODS
  Two hundred seventy-five middle school and high school athletes (Tanner Stages 2 to 5) volunteered to participate (87 females, 188 males) in a preseason physical screening.
  
  
  METHODS
  Vertical ground reaction forces were used to determine the effects of sex and pubertal stage on the calculated measures. Subjects performed 3 drop vertical jumps onto a portable force platform.
  
  
  RESULTS
  Females demonstrated no increase in vertical jump height whereas males increased on average 12.5% between pubertal stages (P=0.002). The ratios of the drop landing force to drop take-off and maximum landing force to maximum take-off force were decreased in males as they matured (P<0.05) whereas females did not change between pubertal stages.
  
  
  CONCLUSIONS
  Preparticipation physical examination may be used to determine potential high-risk landing force profiles in young athletes before participation. Female athletes may exhibit high-risk landing profiles at all stages of pubertal development that may increase risk of injury during landing compared with males.
  
  
  CONCLUSIONS
  Preseason intervention may be warranted for females with high-risk landing profiles identified during preparticipation physical examination.
authors.affiliation: Cincinnati Children's Hospital Research Foundation, Sports Medicine Biodynamics Center and Human Performance Laboratory, Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 45229, USA. tim.hewett@cchmc.org
authors.forename: Timothy E
authors.initials: TE
authors.lastname: Hewett
authors.forename: Gregory D
authors.initials: GD
authors.lastname: Myer
authors.forename: Kevin R
authors.initials: KR
authors.lastname: Ford
authors.forename: James R
authors.initials: JR
authors.lastname: Slauterbeck
mesh_terms: D000293:Adolescent; D000367:Age Factors; D000070598:Anterior Cruciate Ligament Injuries; D001696:Biomechanical Phenomena; D002648:Child; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D015994:Incidence; D007718:Knee Injuries / Q000209:etiology*; D008297:Male; D010808:Physical Examination; D011627:Puberty; D018570:Risk Assessment; D012307:Risk Factors; D012737:Sex Factors; D013177:Sports; D013781:Texas