title: The relationship of hamstrings and quadriceps strength to anterior cruciate ligament injury in female athletes.
abstract: OBJECTIVE
  To determine the association of quadriceps and hamstrings strength to anterior cruciate ligament (ACL) injury risk in female athletes. The primary hypothesis was that there would be decreased knee flexor and increased knee extensor strength in female athletes who went on to ACL injured status (FACL) compared to uninjured female (FC) and male (MC) control subjects.
  
  
  METHODS
  Matched case control.
  
  
  METHODS
  Institutional Biomechanics Laboratory.
  
  
  METHODS
  Prospectively measured FACL (n = 22) female athletes who subsequently suffered confirmed noncontact ACL ruptures (16 during soccer and 6 during basketball play) were matched (1:4 ratio) to female controls (FC; n = 88) using limb (dominant or nondominant), pubertal status, sport, and nearest height and mass. In addition, male controls (MC) were matched (1:1 ratio) to FACL to serve as a secondary comparative control.
  
  
  METHODS
  Isokinetic (concentric) knee extension/flexion strength (300 degrees/s).
  
  
  RESULTS
  FACL subjects had decreased hamstrings strength compared to MC (15%; 95% CI, 1 to 27%; P = 0.04). FC were not different from MC in hamstrings strength. Conversely, FACL subjects did not differ compared to the MC in quadriceps strength, and the FC demonstrated decreased quadriceps strength relative to MC (10%; 95% CI, 3 to 18%; P = 0.01).
  
  
  CONCLUSIONS
  The results of this investigation indicate that female athletes who suffered ACL injury subsequent to strength testing had a combination of decreased hamstrings strength but not quadriceps strength compared to males. In direct contrast, female athletes who did not go on to ACL injury had decreased quadriceps strength and similar hamstrings strength compared to matched male athletes.
authors.affiliation: Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio 45229, USA. greg.myer@chmcc.org
authors.forename: Gregory D
authors.initials: GD
authors.lastname: Myer
authors.forename: Kevin R
authors.initials: KR
authors.lastname: Ford
authors.forename: Kim D
authors.initials: KD
authors.lastname: Barber Foss
authors.forename: Chunyan
authors.initials: C
authors.lastname: Liu
authors.forename: Todd G
authors.initials: TG
authors.lastname: Nick
authors.forename: Timothy E
authors.initials: TE
authors.lastname: Hewett
mesh_terms: D000293:Adolescent; D000070598:Anterior Cruciate Ligament Injuries; D001265:Athletic Injuries / Q000209:etiology*; D001696:Biomechanical Phenomena; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D007718:Knee Injuries / Q000209:etiology; D008297:Male; D053580:Muscle Strength / Q000502:physiology*; D011446:Prospective Studies; D018570:Risk Assessment; D013848:Thigh / Q000502:physiology*; D055815:Young Adult