title: EMG power spectra of intercollegiate athletes and anterior cruciate ligament injury risk in females.
abstract: OBJECTIVE
  Females have a disproportionately high incidence of anterior cruciate ligament (ACL) injuries compared with males in analogous sports. Although the pathogenesis of this higher frequency has not been elucidated, gender differences in neuromuscular control of the knee may play an important role. This study evaluates EMG power spectra of the quadriceps and hamstring muscles during dynamic, fatiguing exercise to examine differences between male and female intercollegiate athletes.
  
  
  METHODS
  Fifty-one collegiate basketball and soccer players (25 female, 26 male) were studied. Maximum voluntary contraction (MVC) was determined for knee flexion and extension. Three consecutive 2-min bouts of isokinetic knee flexion and extension exercise were performed at 40% MVC. EMG activity in the biceps femoris and vastus medialis obliquus was recorded using bipolar surface electrodes.
  
  
  RESULTS
  MVC normalized to body weight was significantly greater in males than in females for the quadriceps (P< 0.01). Quadriceps coactivation ratios were significantly higher in females than in males during knee flexion exercises (P< 0.01).
  
  
  CONCLUSIONS
  This study demonstrates differences in the EMG power spectra for females when compared with a matched group of males. Increased quadriceps coactivation in females may increase anterior tibial loads under dynamic conditions, thus placing the ACL at higher risk for injury in the female athlete.
authors.affiliation: Department of Orthopaedic Surgery, University of California San Diego, San Diego, CA 92103-8894, USA.
authors.forename: Klane K
authors.initials: KK
authors.lastname: White
authors.forename: Steven S
authors.initials: SS
authors.lastname: Lee
authors.forename: Adnan
authors.initials: A
authors.lastname: Cutuk
authors.forename: Alan R
authors.initials: AR
authors.lastname: Hargens
authors.forename: Robert A
authors.initials: RA
authors.lastname: Pedowitz
mesh_terms: D000293:Adolescent; D000328:Adult; D016118:Anterior Cruciate Ligament / Q000503:physiopathology; D000070598:Anterior Cruciate Ligament Injuries; D001265:Athletic Injuries / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology; D001490:Basketball / Q000293:injuries*; D001835:Body Weight / Q000502:physiology; D002140:California; D004576:Electromyography / Q000379:methods*; D005080:Exercise Test; D005260:Female; D006801:Humans; D008297:Male; D009119:Muscle Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology; D016059:Range of Motion, Articular / Q000502:physiology; D012307:Risk Factors; D012572:School Health Services; D012737:Sex Factors; D012916:Soccer / Q000293:injuries*; D013997:Time Factors; D016387:Women's Health