Risk factors for leg injuries in female soccer players: a prospective investigation during one out-door season.

The following possible risk factors for leg injuries in female soccer players were studied: age, anatomical alignment, generalized joint laxity, thigh muscle torque, muscle flexibility, ligamentous laxity of the knee and ankle joints, recent injuries, and duration of soccer exposure. A total of 146 players from 13 teams in the second and third Swedish divisions underwent clinical examination, isokinetic measurements of quadriceps and hamstring torques, and testing of postural sway of the legs. All soccer-related leg injuries resulting in absence from at least one scheduled practice session or game were recorded during one outdoor season (April-October). In 50 players there were 61 traumatic injuries, and 17 players sustained 19 overuse injuries. The overall injury incidence rate (traumatic and overuse) was 5.49/1000 h of soccer. Variables significantly increasing the risk of traumatic leg injuries included generalized joint laxity, low postural sway of the legs, hyperextension of the knee joint, and a low hamstring-to-quadriceps ratio during concentric action. Multivariate logistic regression showed hyperextension of the knee joint, a low postural sway, reduced H/Q ratio during concentric action, and a higher exposure to soccer to significantly increase the risk of traumatic leg injury. All five players who suffered an anterior cruciate ligament injury during the study period had a lower hamstring-to-quadriceps ratio during concentric action on the injured side than on their noninjured side.