By Amy Norton

NEW YORK (Reuters Health) - Weakness in the muscles that support the hips may be a common contributor to many overuse injuries in runners, a new research review suggests.

For most runners, overuse injuries occur at or below the knee -- including chronic knee pain, shin splints, Achilles tendonitis and pain in the sole of the foot. The new study, a review of previous research findings published since 1980, found that weakness in the hip muscles may translate into a higher risk of these lower-leg injuries.

The findings are published in the journal Sports Health.

"The hip muscles are responsible for stabilizing the leg during running," explained lead researcher Dr. Reed Ferber, of the University of Calgary in Alberta, Canada.

"If these muscles are weak, or become fatigued easily," he told Reuters Health, "there is less control of the leg and the risk of injury increases."

If, for example, the hip abductors -- muscles at the outer hip -- are weak, this allows the knee to roll too far inward, toward the midline of the body. That, Ferber explained, can set runners up for patellofemoral pain syndrome, which causes pain under and around the kneecap, or iliotibial band syndrome, where pain arises in the outside of the knee.

The implication, according to Ferber and his colleagues, is that strengthening the hip muscles could go a long way toward preventing or resolving many running injuries.

It's estimated that up to 70 percent of runners sustain an overuse injury each year, they note in the their report, and about half of those injuries occur in the knee.

In other research, Ferber and his colleagues have found that six weeks of hip-muscle training can alleviate pain from various running injuries in most patients. The researchers are currently studying whether such strength training also prevents overuse injuries.

Stretching the hip muscles is important for runners as well, according to Ferber. However, he said, studies indicate that strengthening the muscles may be much more important when it comes to reducing injury risk.

SOURCE: Sports Health, May/June 2009.

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