The incidence of anterior cruciate ligament (ACL) injury remains high in young athletes. Because female athletes have a much higher incidence of ACL injuries in sports such as basketball and team handball than male athletes, the IOC Medical Commission invited a multidisciplinary group of ACL expert clinicians and scientists to (1) review current evidence including data from the new Scandinavian ACL registries; (2) critically evaluate highquality studies of injury mechanics; (3) consider the key elements of successful prevention programmes; (4) summarise clinical management including surgery and conservative management; and (5) identify areas for further research. Risk factors for female athletes suffering ACL injury include: (1) being in the preovulatory phase of the menstrual cycle compared with the postovulatory phase; (2) having decreased intercondylar notch width on plain radiography; and (3) developing increased knee abduction moment (a valgus intersegmental torque) during impact on landing. Well-designed injury prevention programmes reduce the risk of ACL for athletes, particularly women. These programmes attempt to alter dynamic loading of the tibiofemoral joint through neuromuscular and proprioceptive training. They emphasise proper landing and cutting techniques. This includes landing softly on the forefoot and rolling back to the rearfoot, engaging knee and hip flexion and, where possible, landing on two feet. Players are trained to avoid excessive dynamic valgus of the knee and to focus on the ''knee over toe position'' when cutting.The incidence of anterior cruciate ligament (ACL) injury remains high, especially in young athletes aged 14-19 years. In spite of the fact that some successful prevention programmes have been introduced, ACL injury continues to be the largest single problem in orthopaedic sports medicine, with the incidence of non-contact ACL tears being much higher in female athletes in sports such as basketball and team handball than in male athletes.As ACL injury remains a significant problem, especially in young female athletes, procedures for improved prevention and management are needed. The mechanism of ACL injury is an important focus of discussion, as an ACL tear is more often a non-contact event with a deceleration or a change of direction manoeuvre than a contact or direct blow injury. A prophylactic neuromuscular and proprioceptive training programme may reduce the number of ACL injuries in female athletes.The President of the International Olympic Committee (IOC) Jacques Rogge stated in 2001 that ''the most important goal of the IOC Medical Commission is to protect the health of the athlete''. The IOC Medical Commission therefore invited a group of physicians, physical therapists, biomechanists and scientists active in ACL research to review current evidence relating to risk factors, prevention programmes and the need for further research concerning non-contact ACL injury in young female athletes. EPIDEMIOLOGY OF ANTERIOR CRUCIATE LIGAMENT INJURIESThe incidence of ACL ...

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In this study, we examined hamstring muscle activation at different running speeds to help better understand the functional characteristics of each hamstring muscle. Eight healthy male track and field athletes (20.1 +/- 1.1 years) performed treadmill running at 50%, 75%, 85%, and 95% of their maximum velocity. Lower extremity kinematics of the hip and knee joint were calculated. The surface electromyographic activities of the biceps femoris and semitendinosus muscles were also recorded. Increasing the running speed from 85% to 95% significantly increased the activation of the hamstring muscles during the late swing phase, while lower extremity kinematics did not change significantly. During the middle swing phase, the activity of the semitendinosus muscle was significantly greater than that of the biceps femoris muscle at 75%, 85%, and 95% of running speed. Statistically significant differences in peak activation time were observed between the biceps femoris and semitendinosus during 95%max running (P < 0.05 for stance phase, P < 0.01 for late swing phase). Significant differences in the activation patterns between the biceps femoris and semitendinosus muscles were observed as running speed was increased, indicating that complex neuromuscular coordination patterns occurred during the running cycle at near maximum sprinting speeds.

Our results suggest that loss of feedback from mechanoreceptors in ACL is the underlying mechanism of weakness of QF in patients with ACL lesion. This conclusion is based on chronic suppression of recruitment of high-threshold motor units during voluntary contraction because ACL lesion leads to chronic reduction in Ia-feedback to muscles around the knee due to a lack of feedback from ACL to gamma motor neurons.