Weak in the Knees?
Hormones and anatomy make women more prone to knee injuries.
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
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.