May 5, 2003 -- Study of NCAA athletes shows why women are eight times more likely to get ACL knee injuries than men. Specific exercises may protect women's knees from injury and re-injury, the findings suggest.
The ACL is the anterior cruciate ligament. It's one of two ligaments that crisscross in the knee, making it stable. When a person jumps in the air and then comes down on one leg as he or she cuts off in a new direction, the ACL can rupture. It's a common knee injury in basketball, soccer, and other sports that require jumping, pivoting, and cutting.
Women who play such sports are much more likely to have ACL knee injuries than men. Edward M. Wojtys, MD, medical director of the sports medicine program at the University of Michigan, Ann Arbor, wondered why. He asked for help from 12 women and 12 men who play NCAA Division-I basketball, volleyball, and soccer, and from 14 women and 14 men who play endurance sports -- bicycling, crew, and running.
Wojtys and colleagues designed a contraption that simulated a pivoting maneuver when landing on one foot. It also measured how well the athletes could stiffen their knee muscles. Even when male and female athletes were matched for age, height, weight, shoe size, activity level, and body mass index, the men were able to stiffen their knee muscles more than the women.
"Historically, training has been the same for both men and women," Wojtys says in a news release. "This may not be the correct approach."
The problem isn't that women can't develop knee-stabilizing muscles. Surprisingly, women who engaged in non-pivoting sports could voluntarily stiffen their knee muscles better than women in pivoting sports. They could even do it better than men in non-pivoting sports.
This suggests that it would be possible to decrease women's ACL knee injuries by training them to strengthen protective muscles. Wojtys says coaches and trainers should rethink their muscle-training programs to account for the differences in the ways women and men use their knees.
Wojtys and colleagues report their findings in the May issue of The Journal of Bone and Joint Surgery.