Be Nice to Your Knees

Female athletes are more likely to damage this crucial joint.

By Stephen Hanks

September 2006

I was playing second base during a recent over-40 baseball game when an opposing hitter I’ve known for years ripped a ball down the leftfield line. Normally he would have coasted easily into second with a double, but this being a game played by a lot of guys on the other side of 50, he hobbled into the base just ahead of the throw. “How are your knees?” he asked me as he bent over to catch his breath before the next pitch. After giving him a quick “fine” with the knock-on-wood motion, he replied, “You’re lucky because mine are shot.”

He was right. I am lucky. I’ve been playing sports since I was seven and since then I’ve had a fractured ankle, a strained quad, a torn hamstring, hammer toe and plantar fasciitis (a painful heel ailment that lasted for a year), but I’ve never had a knee problem. While researching this story, I learned that my pain-free knees may have more to do with my gender than with good fortune.

Sobering Statistics

The women and knee-injury numbers are not pretty. According to a variety of studies, females are two to eight times more likely to suffer knee injuries than men. During sports, it’s four to six times more. In fact, the National Collegiate Athletic Association (NCAA) recently estimated that of the approximately 100,000 women participating in inter-collegiate sports each year, one in 10 suffers a knee injury, usually to the anterior cruciate ligament. The ACL, located in the center of the joint, is the main stabilizing ligament of the knee, joining the tibia (the main shinbone) with the femur (the thighbone). The ACL prevents the tibia from sliding out in front of the femur and allows the knee stability when rotating. When the ACL blows out, it usually requires surgery and, depending on the injury’s severity, weeks to months of rehabilitation.

As for the general population, the American Academy of Orthopedic Surgeons (AAOS) estimates that each year 9.5 million Americans seek care for knee problems and that 38,000 American women experience ACL tears. So why are active women more susceptible to knee injuries?
“There are lots of theories,” says Dr. Frank Noyes, president of the Cincinnati Sports Medicine and Orthopedic Center and once an orthopedist for the National Football League’s Cincinnati Bengals.

Among a number of factors, Noyes cites the inherent difference in the male and female bodies. Most untrained female athletes possess stronger quadriceps muscles in the front of the thigh than hamstring muscles in back of the thigh, which puts increased pressure on knee ligaments when pivoting and landing during sports such as soccer and basketball. (The AAOS says nearly 60% of all injuries in female basketball players occur when landing.) Women also have a wider pelvis, which changes the angle of the knee joint, contributing to injuries in sports that require jumping.

Estrogen may also be a culprit. Not only do experts believe estrogen makes women’s ligaments smaller than men’s, studies have shown that women are more likely to suffer a knee injury during ovulation, when estrogen levels are highest. Many women tear ACLs just before or after their menstrual periods. Why? The experts haven’t figured that out yet.

Preventative Measures

But probably the biggest factor in women’s susceptibility to knee injuries is the lack of proper training, conditioning and strengthening, especially in non-competitive athletes. The knee is the largest joint in the body and one of the most easily injured, but you can’t just strengthen this joint directly the way you would a muscle. You have to enhance the strength and flexibility of all the surrounding leg muscles that support the cartilage and ligaments which control a knee’s motion.

For a study at the Cincinnati Sports-medicine Research and Education Foundation, a test group of 366 female high school athletes went through six weeks of flexibility, weight training, and coaching, with emphasis on how to land after jumps. Two other groups—one of 434 men and one of 463 women—weren’t given any training. Almost all the athletes were monitored during their volleyball, soccer and basketball seasons, activities that required a lot of running, pivoting and jumping. The results? Untrained female soccer and basketball players suffered 5.8 times the number of knee injuries than the men did. And while training reduced the number of injuries in the test group, those women still had 2.4 times the number of injured knees as the guys.

One of the studies’ conclusions was that the hamstrings of female athletes should be at least 15% stronger than the quadriceps. The study also recommended that women do strength-training exercises for hamstring and calf muscles long before a sports season starts, and balance training to understand how to jump and land properly. The AAOS has observed that women don’t bend their knees as much as men when turning, pivoting or landing from a jump. This puts pressure on the knee joint by exposing it to more force per pound of body weight. The surgeons say avoiding the vulnerable “knock-kneed” position and learning to crouch and bend at the knees and hips during sports could reduce pressure on knee ligaments.

Kneeded Knowledge

Besides doing specialized exercises, it also turns out that losing weight—surprise!—can help you avoid knee injuries. Researchers at Wake Forest recently studied 142 overweight adults over 60 who suffered from knee osteoarthritis and found that for every pound of weight dropped there was a four-pound reduction in the load on the knee for each step, which would be more than 4,800 pounds per mile walked.

Thanks to arthroscopic surgery, athletes are sometimes back on the field four to eight weeks after damaging an ACL. But that doesn’t mean there aren’t long-term ramifications from knee injuries, especially for women. A recent Mayo Clinic study reported that even after corrective surgery, ACL injuries can result in bone loss in the femur, tibia and patella (kneecap), which is only partly reversed by physical therapy and can lead to arthritic conditions and osteoporotic fractures down the road.

And if you are currently dealing with damaged knees—whether you’re athletic or not—there are supplements you can take to minimize the problem. Glucosamine, for example, supports cartilage and acts as a joint lubricant. MSM (methylsulfonylmethane) is an organic source of sulfur, one of the building blocks of joint health. Put the two together and you’ve a great combination for strengthening the knee and diminishing knee pain.

So whether you compete in organized athletics or simply play for fun, you need to be aware of the needs of your knees. You have miles more to walk—and run—in this life. You might as well do it without hobbling.

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