Researchers in the Neuromuscular Research Laboratory at UPMC Health System's Center for Sports Medicine have begun a four- year study of the effects of a physical training program they have designed to determine if it may help reduce the incidence of anterior cruciate ligament (ACL) injuries in high school and collegiate female athletes. Female athletes are up to eight times more susceptible to ACL injuries than their male counterparts.

The ACL is the main stabilizing ligament in the knee joint, connecting the femur to the tibia. ACL tears can be devastating, resulting in painful knee instability. They almost always require surgical reconstruction, followed by months of rehabilitation.

"We believe the data from this study will provide a basis for preparing female athletes for safer participation in fitness and sports activities by reducing their vulnerability to knee ligament injuries while perhaps enhancing their athletic performance as well," said Scott Lephart, Ph.D., director of UPMC's Neuromuscular Research Lab and principal investigator for the UPMC study.

ACL injuries are common in fast-moving contact sports that involve sudden starting, stopping, turning, jumping and landing such as in basketball, football, soccer and lacrosse. However, numerous studies over the past decade have shown that female athletes are two to eight times more likely than their male counterparts to injure their ACLs. For example, in college basketball today, ACL injuries are occurring eight times more often in females than in males; and at the high school level, the ratio is about four to one.

Sports injury researchers during the past decade have theorized that factors contributing to the disproportionate rate of ACL injury for females include: female hormones making the ligaments more lax during a certain phase of the menstrual cycle; anatomical differences in the ligament itself -- perhaps a woman's ACL is smaller and weaker; and the biomechanical design of a female's wider hips, which could place added stress on the ACL.

Dr. Lephart, who is also an associate professor in the University of Pittsburgh's School of Health and Rehabilitation Sciences and the School of Medicine's department of orthopaedic surgery, believes that the most important factor making female athletes more vulnerable to ACL tears is that they have weaker quadricep and hamstring musculature supporting the knee joint. He believes the weaker supporting musculature causes women to unconsciously plant their feet differently than men - with stiffer knee position and lack of balanced neuromuscular control -- during sudden cutting, jumping, landing, starting and stopping.

Several preliminary studies in the Neuromuscular Research Lab have revealed strength and neuromuscular control differences in females. The studies further showed that females with ACL injuries who underwent appropriate rehabilitation were able to overcome the strength differences and develop muscle activation patterns that enhance knee function. Dr. Lephart's team is now implementing these concepts into the prevention study for un- injured females.

In UPMC's current prevention study, the researchers will try to determine if a specific training program they have designed will reduce the vulnerability and therefore the incidence of female ACL injuries among study participants over a four-year period. Female high school and collegiate athletes are undergoing specific muscle strengthening and conditioning, neuromuscular control and balance training as well as skills training related to proper biomechanics while landing, cutting, jumping and stopping.

Phase one of the study has enrolled more than 60 high school female athletes to perform the exercises over a two-month period, after which the girls will be re-tested to determine if exercises do indeed induce the desired changes. Then, the researchers will begin to monitor injury rates over the four- year period to see the effectiveness of the preventative training in reducing ACL injury rates in the females.

The Jewish Healthcare Foundation is funding the four-year study, which will enroll more than 300 female athletes ages 8 to 24.

The Neuromuscular Research Laboratory at the UPMC Center for Sports Medicine is a state-of-the-art clinical research center whose staff of world-renowned sports injury investigators study the contribution of muscle to joint stability. The laboratory has been recognized with numerous international scientific awards for research models of the influences of gender, aging, fatigue as well as the effects of injury, surgery and rehabilitation on joint stability.

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