title: A prospective cohort study of hamstring injuries in competitive sprinters: preseason muscle imbalance as a possible risk factor.
abstract: BACKGROUND
  Hamstring injuries are common in sprinters. Identifying preseason risk factors is essential to target injury-prone athletes and develop injury preventive measures.
  
  
  OBJECTIVE
  To investigate the incidence of hamstring muscle injury in sprinters over an athletic season and to explore the preseason predictor of this injury.
  
  
  METHODS
  Prospective cohort study.
  
  
  METHODS
  44 sprinters from the Hong Kong Sports Institute, the Hong Kong Amateur Athletic Association and intercollegiate athletic teams were recruited.
  
  
  METHODS
  Preseason assessment of hamstring flexibility, concentric and eccentric isokinetic peak torque and peak torque angle were obtained at the beginning of an athletic season. The athletes were followed over 12 months and were asked to report all injuries resulting from training and competition.
  
  
  RESULTS
  Eight athletes sustained hamstring injuries over the season. The injury rate was 0.87 per 1000 h of exposure. The incidence of injuries was higher at the beginning of the season, with 58.3% injuries occurring in the first 100 h of exposure. Cox regression analysis revealed that athletes with a decrease in the hamstring : quadriceps peak torque ratio of less than 0.60 at an angular velocity of 180 degrees/s have a 17-fold increased risk of hamstring injury.
  
  
  CONCLUSIONS
  Performing preseason hamstring : quadriceps peak torque ratio assessments may be useful to identify sprinters susceptible to hamstring injury.
authors.affiliation: Centre for Sports Training and Rehabilitation, Department of Rehabilitation Sciences, The Hong Kong Polytechnic University, Kowloon, Hong Kong.
authors.forename: S S
authors.initials: SS
authors.lastname: Yeung
authors.forename: A M Y
authors.initials: AM
authors.lastname: Suen
authors.forename: E W
authors.initials: EW
authors.lastname: Yeung
mesh_terms: D005260:Female; D006723:Hong Kong / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D008297:Male; D053580:Muscle Strength / Q000502:physiology; D018482:Muscle, Skeletal / Q000293:injuries*; D011446:Prospective Studies; D012044:Regression Analysis; D012307:Risk Factors; D012420:Running / Q000293:injuries*; D013848:Thigh / Q000293:injuries; D055815:Young Adult