title: Effects of a 2-hour cheerleading practice on dynamic postural stability, knee laxity, and hamstring extensibility.
abstract: METHODS
  One group; pretest, posttest design.
  
  
  OBJECTIVE
  To assess the effect of a 2-hour cheerleading practice on the anterior knee laxity, hamstring extensibility, and dynamic postural stability (preferred stance leg during vision-denied unilateral stance) of 17 nonimpaired members of a college cheerleading team (8 females, 9 males; 18-25 years old).
  
  
  BACKGROUND
  Anterior knee laxity and hamstring extensibility increase following exercise. The relationship between exercise induced anterior knee laxity, hamstring extensibility, and dynamic postural stability, however, has not been examined.
  
  
  METHODS
  Pre- and postpractice measurements were compared using paired t tests and Bonferroni's correction for multiple comparisons. A 3 x 2 analysis of variance (force level applied to the arthrometer by condition) and Tukey honest significant difference post hoc test were used to evaluate specific arthrometer force level by condition effects (P < .05).
  
  
  RESULTS
  Mean laxity at 133 N and hamstring extensibility increased (mean +/- SD) 1.5 +/- 1 mm and 3 +/- 4 degrees, respectively, following practice. Mean medial-lateral stabiliometer platform angulation (frontal plane position) moved medially following practice (2.9 +/- 3 degrees) and produced a weak correlation with increased knee laxity (r = 0.58). Hamstring extensibility did not significantly relate to stabiliometry or knee laxity variables.
  
  
  CONCLUSIONS
  The relationship between the medially directed platform angulation and the increase in anterior knee laxity following cheerleading practice suggests a relationship between subtalar joint position and anterior cruciate ligament strain.
authors.affiliation: Physical Therapy Program, University of Kentucky Center for Rural Health, Hazard, USA.
authors.forename: A
authors.initials: A
authors.lastname: Rowe
authors.forename: S
authors.initials: S
authors.lastname: Wright
authors.forename: J
authors.initials: J
authors.lastname: Nyland
authors.forename: D N
authors.initials: DN
authors.lastname: Caborn
authors.forename: R
authors.initials: R
authors.lastname: Kling
mesh_terms: D000293:Adolescent; D000328:Adult; D001265:Athletic Injuries / Q000209:etiology; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000209:etiology / Q000503:physiopathology*; D007719:Knee Joint / Q000502:physiology*; D008297:Male; D018763:Muscle Fatigue; D010807:Physical Endurance; D011187:Posture; D016059:Range of Motion, Articular; D013177:Sports