08/06/2012 03:14 pm ET Updated Oct 06, 2012

Along With Gold and Glory, Injuries a Growing Pain for Female Athletes

What would my medical predecessors from the 19th century have thought about the cavalcade of athletes, especially the history-making members of the U.S. team, who so proudly marched into the Olympic stadium in London for the 2012 games?

When these modern games were revived in the 1890s, physicians then argued successfully that women should be limited -- encouraged to applaud male athletes but not to compete because the amount of energy they needed for reproduction left them little for physical, psychic or intellectual endeavors.

That prognosis never has appeared more preposterous. Not just because for the first time in Olympic history Team USA boasts more women (296), including 13 who have kids, than men (261). But because, thanks largely to Title IX of the Education Amendments -- which just turned 40 years old -- more girls and young women than ever are competing more intensely than ever in a wide range of sports.

Energy isn't an issue for women in athletics. But we also know now from cheering on two generations of girls who have grown up in organized sports that female athletes are at a much greater risk for certain musculoskeletal injuries than their male counterparts.

On average, females are more likely than males to: suffer knee injuries, such as tears to the anterior cruciate ligament (ACL) or meniscus (the rubbery, C-shaped disc that cushions our knees); sustain shoulder and hip injuries; sprain ankles and endure stress fractures. It's not just elite athletes, either. From youth sports at the park to NCAA playoffs at Division I colleges, Ace bandages and knee braces are almost as prevalent as ponytails.

Blood, Sweat and ACL tears

One of the greatest gender gaps is in the occurrence of ACL damage. The ACL is a rubber band-like fiber that binds the knee-joint, attaching the femur (thigh bone) to the tibia (shin bone). Girls and women are up to eight times more likely than their male counterparts to tear an ACL.

ACL injuries are especially common in sports like soccer, basketball, football and skiing with their jumping and sudden stops and changes in direction. These injuries can keep a player on the bench for a year and may require surgery to repair. Even worse, ACL tears increase the risk for developing osteoarthritis later in life by as much as 10 times.

When boys injure an ACL, it's often the result of direct contact. For girls, it's more often the result of the positions in which they land.

Gender disparity begins around puberty when girls' pelvis bones start to widen. This increases the angle at which the femur attaches to the tibia. The steeper the angle, the more the knees tend to turn in and the bottom of the legs splay out, causing a knock-kneed stance that puts excess stress on the ACL. These same mechanics also can cause increased ankle and hip injuries in female athletes.

During puberty, girls also experience a rapid increase in size and weight without increased neuromuscular power. Compounding the situation, estrogen causes ligaments to be more relaxed and flexible. Though a benefit for some sports, this increases the risk for injury.

Meanwhile, boys entering puberty benefit from higher levels of testosterone that enable them to add muscle and get stronger -- even with little effort.

Another factor may be attributed to the tendency for girls to have shorter and more rounded shin bones at the knee-joint. Researchers recently compared magnetic resonance imaging (MRI) scans of male and female athletes and found this trait in both women with and without ACL injuries, but only in the men who had ACL-injuries

Studies show that girls are particularly prone to ACL injuries during adolescence. In fact, most ACL reconstructions in females occur during the 15- to 19-year-old age range. Research also has suggested that females have a greater likelihood of tearing an ACL in the days just prior to menstruating. That doesn't mean that they should limit their playing at that time. But the more we understand these injury patterns, the better we can develop more effective prevention programs.

There are several efforts already aimed at teaching young women how to jump and to run with better alignment, as well as to build their muscles around the back, butt and legs. The Prevent Injury and Enhance Performance (PEP) Program, developed by the Santa Monica Sports Medicine Foundation, for example, includes warm-up drills like lateral diagonal runs, so women athletes learn to pivot off a leg without the knee collapsing inward. Performance Enhancement and Kinetic Control (PEAK), developed by the sports medicine research laboratory at the University of North Carolina at Chapel Hill, includes exercises such as one-legged squats and lateral jumps.

Female athletes also are at greater risk for shoulder pain, due to the combination of less top-body strength and greater ligament flexibility than males. As a result, women in sports like swimming, softball or volleyball typically are more apt to suffer from rotator cuff weakness, tightness and pain; strengthening exercises can greatly improve this.

Overuse is a frequent cause of shoulder and other injuries in females, too. These include muscle or joint injuries and stress fractures that result from gradual and repetitive trauma. According to a recent study, overuse injuries comprise almost 30 percent of all injuries sustained by college athletes; 62 percent of these injuries occur in female athletes.

The Female Athlete Triad

Another factor that separates the genders in athletics is known as the female athlete triad. This is the cycle caused by athletes failing to eat enough calories to support intense exercise resulting in a low body fat mass. It leads to decreases in estrogen, causing a girl's periods to become irregular or stop altogether. Some girls may never even get their first period because they have trained so hard. Low estrogen levels and poor nutrition, especially low calcium and vitamin D intake, can lead to osteoporosis, in which bones lose density, weaken and become susceptible to stress fractures or small cracks. A new study shows that girls and young women who got lots of vitamin D through their diet and supplements were half as likely to suffer a stress fracture as those who didn't get much of the vitamin.

Fifteen percent to 62 percent of college female athletes report a history of eating disorders. Sports where a thin appearance is valued, such as gymnastics, figure skating and cheerleading, can put girls at an increased risk for the female athlete triad.

Little to Cheer About

A proclivity for female athlete triad is not the biggest reason, however, that cheering (cheerleading or cheer dancing) is considered the most dangerous sport for girls and young women. Cheering accounts for 70.5 percent of all collegiate female catastrophic sports injuries and 65.2 percent of all high school female catastrophic sports injuries, those serious enough to potentially cause permanent disability.

Central to the problem is that, despite the complex acrobatics involved in cheering, it is not designated nor regulated as a sport in most states. That means its participants, especially young women, "are not under the watchful medical eye as many other athletes are," points out my colleague Margo Apostolos, Ph.D., co-director of Cedars-Sinai/USC School of Dance Medicine Center. "Sports teams have trainers on the field at practice and games. If athletes in these organized and regulated programs are injured, they are pulled from practice or taped. They benefit from so many more precautions."

Several groups have sprung up to encourage stricter standards -- including limiting human pyramids to no more than 2 1/2 body lengths in height, as well as curtailing use of certain types of add-on equipment and tumbling and tossing stunts.

If cheerleading were under the control of athletic departments, it would benefit from more qualified coaches, certified athletic trainers and better practice facilities.

"You often see cheerleaders and dancers practicing wherever they can -- on uneven grass surfaces and even cement," adds Apostolos, who works with another colleague Glenn Pfeffer, MD, an orthopedic surgeon and foot and ankle specialist to help those injured in cheering or dance.

Proper equipment and coaching are important in preventing injury in any sport. So is conditioning, a healthy diet and knowing when to rest. By avoiding injury, young women and men get to stay in the game -- and for girls and young women, we know that athletics can offer major benefits. Studies show that those who participate in sports are more likely to get better grades, graduate high school, find employment and even give birth to healthier babies down the road. Some may even win multiple gold medals, and I hope you will join me on the sidelines in a hearty cheer for the accomplishments of all our Olympians -- including and especially those amazing women.