Competing against the body

Jen Shingleton '03 will never forget the second match of the 2000-2001 Princeton women's squash team's season.

"I knew something serious had happened. I had been facing the left-hand side, preparing to hit a backhand, but turned because I had to retrieve the ball on the right side. It is a movement you do in squash all the time. But I turned one way and my knee totally gave out." Shingleton '03 explained. "As soon as I felt the pain, I collapsed."

She was forced to forfeit her match, but the trainer on hand assured her that her knee was probably fine. She hadn't heard an ominous popping sound and she could still manage a limp.

But the news from her team doctor the following Monday was not so promising. "Within two seconds Dr. Castello knew," Shingleton said. "I had torn my ACL."

For Shingleton, this news was worse than the pain of the injury. She cringed at the words because she knew exactly what it meant. Too many of her friends had also torn their anterior cruciate ligament — a band that runs at an angle through the knee joint and connects the shin and the thighbones. A painful surgery, days of immobilization and nine long months of rehab would lie ahead.

This story is becoming all too common among female collegiate athletes around the nation. Carrie Hughes, an athletic trainer at Princeton, noted that out of 600 varsity female athletes, she sees about three torn ACLs every year. A recent NCAA report showed that the ACL injury rate for female soccer players was more than two times higher than that for men — 0.31 compared to 0.13 occurrences per 1,000 athlete exposures. In basketball, women were four times as likely to injure their ACL (0.29 versus 0.07).

The dramatic increase in the number of women and girls playing sports and the intensity at which they are playing has brought this issue to the attention of coaches and trainers. Women's sports were once played in a slower, defensive style. Today women play with much more speed, precision and power.

"It is amazing — all of the female athletes that have had this same injury," commented Shingleton. "The week after it happened people would ask me what happened and would say, 'Oh, I did that last year.' I feel it is like a right of passage for female athletes."

Three months out of surgery, Shingleton spends about two hours a day, along with the other members of her "ACL support group" — a collection of seven Princeton athletes recovering from ACL surgery — completing rehabilitation exercises.

But despite the great company, the process is frustrating for Shingleton. "It's been three months and I still can't jog. [I can do] only a light stair master — nothing with high resistance. I am mostly working on strengthening my leg," she said. "You wouldn't believe how quickly it atrophies after surgery." She is not only working to rebuild her hamstring, quadriceps and calf muscle, but because the graft to replace the torn ACL was taken from the patella tendon, she will need to re-strengthen that region as well.

The rehabilitation process may be difficult already, but psychological stress can also figure into the injury. "I am terrified I am going to tear the other one. I couldn't go through the surgery again," Shingleton said. "It was horrible. I know people become much less confident when they return to playing."

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Surgical repair of the torn ACL makes it less likely to tear than before. But what worries Shingleton and injured athletes is that they are now more likely to tear the other ACL by overcompensating for the healed but weaker one.

There are at least three different theories explaining why females have a much higher risk of knee injuries than men do. Most trainers, like Hughes, believe it is a combination of the three factors that result in a high ACL injury rate.

According to the hormonal theory, a surge in estrogen during a woman's menstrual cycle loosens the ACL, making it easier to tear.

The second theory, the anatomical theory — which focuses on the female's narrower femoral notch, increased Q-angle, and knee and foot dynamics — has generally been given the most attention. The femoral notch, which is the space at the bottom of the femur through which the ACL runs, is narrower in females. This can have a shearing effect on the ACL by the femur. Women also have much wider hips than men, giving them to a greater Q-angle — the measure of the angle between the quadriceps in the front of the thigh and the patellar tendon in the knee. A large Q-angle naturally results in a greater angle between the femur and the tibia. This, in addition to a lower center of gravity, places extra pressure on the knee. A large Q-angle also results in a more pronated foot, further stressing the knee.

Unfortunately, the anatomical theory deals only with possible causes that are out of a female athlete's control. But is there any way to possibly prevent torn ACLs? If the third theory, which has been gaining support in the last few years, correctly or at least partially, explains the rash of female injuries, then there is hope.

According to the neuromuscular theory, women injure their knees more often than men because they use their leg muscles differently. Women's muscles are usually less balanced than men's are. Their quadriceps muscles are stronger than their hamstrings. When the powerful quadriceps pulls at the ACL, the weak hamstrings cannot resist and stabilize the knee joint.

Imbalances like these, however, can be controlled. Many doctors have devised special technique analysis and strength-training programs designed to identify and correct muscle imbalances. Although all of the programs differ slightly, most involve weights, stretching and plyometrics to "retrain" female athletes.

Many trainers have noted that women come to college with skills that are not "bio-mechanically sound." For example, among basketball players, females tend to jump and land with their legs straight. This places forces four times greater than one's body weight on the knee alone.

Some trainers believe this can be corrected if females, along with their male counterparts, were taught basic techniques like jumping properly. Whether this is the cause, or if the problem instead stems from natural movements unique to women, no one can say for sure.

Programs can be created to correct these faults. If they already are ingrained firmly in a player's form, however, the programs may be useless. "There are programs that teach the players how to jump and land," Hughes said. "But if they were started earlier it would help."

Techniques that train the athletes to become more aware of their body position should begin at a young age — high school at the latest, most trainers note. If training is begun early, then landing in a squat position when landing on two feet should become natural.

When playing sports that require pivoting and cutting, a multiple-step stop would be second nature — whenever possible, athletes should avoid bringing their weight down on one foot in a single step. And exercises that strengthen hamstrings, gluteus muscles and the inner thighs would be routine.

One recent study, done by The American Journal of Sports Medicine, found that 80 percent of knee injuries women incur could be prevented if athletes in high-risk sports, such as basketball, soccer, and volleyball, were exposed to special training programs.

And many coaches and players are becoming interested in these prevention programs, now that they have been shown to work. Clinics, videotapes and books aimed at teaching the techniques, and strength and flexibility exercises are used to avoid serious knee injuries. Perhaps, with the availability of these precautionary programs, young, aspiring athletes will be able to circumvent much of the pain and frustration Shingleton and thousands of other female athletes have endured.