Feature Archive

Weak in the Knees?

Hormones and anatomy make women more prone to knee injuries.

WebMD Feature

Feb. 21, 2000 (Billings, Montana) -- You might not be a poster child for women's athletics like college basketball star Jaime Walz. But even if your physical endeavors are no more strenuous than the occasional game of softball or Ultimate Frisbee, listen to the lessons that Walz has learned. They just might save your knees.

Walz, a 22-year-old shooting guard for the Western Kentucky University basketball team, plays hard and trains religiously. She also carries a mark shared by countless other active women: a surgical scar on her knee.

The one-time national high school player of the year shredded the anterior cruciate ligament (ACL) in her left knee during a game in January 1998. She leapt in the air, landed on another player's foot, and heard the ominous "pop" that ended her season.

Plenty of Company

Walz doesn't have to look far for sympathy. Two of her teammates ruptured their ACLs in November of the following year. And practically every team they face includes at least one player in a knee brace.

There's a plague of ACL injuries in women's sports, and they're not limited to basketball -- or to professionals, says Timothy Hewett, Ph.D., Director of Applied Research for the Cincinnati Sportsmedicine and Orthopaedic Center. Soccer, volleyball, softball, and other activities that involve jumping, sudden stops and starts, and rapid pivots can all rip a woman's knee ligaments with remarkable ease, he says.

One in 10 female college athletes suffers a major knee injury (usually an ACL tear) every year -- five to six times more often than their male counterparts, Hewett says. And while nobody knows how often casual athletes injure their knees, it's not a rare event, says Hewett, citing a recent study of recreational soccer players that found that women were roughly five times more likely than men to seriously damage their knee ligaments.

Such statistics can be frightening, but with proper training and conditioning, Hewett says, almost any woman can lessen her chances of a knee injury. And with the first-ever scientifically proven program for preventing knee injuries in female athletes, developed by Hewett and his colleagues, safe play may be more possible than ever.

Anatomy, Hormones, and Technique

Why are women so prone to knee trouble? Biology is partly to blame. A woman's relatively wide hips put extra stress on her joints, and female hormones seem to weaken ligaments, Hewett says.

A woman can't do much about her anatomy or hormones, but other factors are within her control. First of all, women can learn to bend their knees when landing from a jump. Many female athletes invite trouble by keeping their legs straight when they jump, pivot, or land, which requires the knee to absorb a shock equal to four times a woman's body weight. But with bent knees, the force drops by 25%.

"It's like pulling an extra person off your back," he says.

Female athletes also tend to develop strong quadriceps muscles and relatively weak hamstrings -- a dangerous imbalance of power, Hewett says. The quads tighten the ACL, while the hamstring muscles relax it. Men generally flex their hamstrings whenever they strain a knee, protecting the ACL. Women, on the other hand, have a tendency to contract their quads.

Nobody knows the cause of these bad habits. "It could be genetic, or it may have something to do with training," Hewett says. Whatever the source of the trouble, it starts early. Hewett has noted straight-legged landings and weak hamstrings in girls as young as eight years old.

Prevention Through Training

With these dangers in mind, Hewett and colleagues developed a six-week training program that incorporates stretching, weight lifting, and seemingly endless jumps with flexed knees. "It's all about mimicking situations that can cause injuries, but staying in control," he says.

In addition to teaching proper jumping technique, the program works to strengthen hamstrings and improve overall balance and agility, says Hewett. Any activity that increases balance and control can help ward off knee injuries, he adds.

The results have been impressive: As reported in the November/December 1999 issue of the American Journal of Sports Medicine, 366 female high school athletes who completed the program were about four times less likely than comparable athletes to suffer a knee injury during a season of play.

Back in Action

As for Walz, spending her off-season sweating through Hewett's program has paid off. She's back to her starring role on the basketball court, playing more minutes and scoring more points -- these days, with flexed knees and strong hamstrings.

All those practice jumps were exhausting, but she added a few inches to her leap and gained some peace of mind. "I play all-out," she says. "I can't stop to worry about my knee."

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