乌鸦传媒

CHICAGO -- The squat lift, an exercise that has long been a standard training technique for athletes, puts inordinate stress on the spine and likely is the cause of chronic stress fractures in young athletes.

That's the conclusion of a study presented here Wednesday at the North American Spine Society annual meeting.

Even when young athletes have textbook form in doing squats, they are risking a hard-to-heal stress fracture of the posterior lumbar spine structure known as the pars interarticularis, researchers reported

"These are high-risk lifts whether you're a child or an adult," said lead author John McClellan, MD, a pediatric and adult spine surgeon at the Nebraska Spine Center in Omaha. "For years, coaches have blamed spinal fractures on kids' poor weightlifting techniques, so we wanted to put that theory to the test."

To do that, McClellan and his co-researchers enlisted 20 male athletes in their 20s, taking x-rays of them in various positions, including normal standing as well as doing front and back squats. They used a bar and weights totaling 95 pounds.

The exercises were done under the guidance of a physical therapist.

The most alarming finding was a change in the slope of the sacrum during a back squat, when the bar was across the upper back.

The average sacral slope increased from 41 degrees in normal standing to 68 degrees while doing a back squat and 58 degrees while doing a front squat, when the bar was across the clavicles.

The researchers concluded that squats significantly increase the slope of sacrum and the alignment of the spine, resulting in a "horizontalization" of the sacrum.

"I agree with him," said Raj Rao, MD, an orthopedic surgeon who practices at Froedtert Hospital in Wauwatosa, Wisc. "It fits and is consistent with the established literature."

Rao, a professor of orthopedic surgery and neurosurgery at the Medical College of Wisconsin, would not go so far as to say squats should not be done at all, but athletes, especially younger ones, need to be cautious, he said.

Doctors said doing a similar type of exercise without weight is much less likely to cause pars stress fractures.

Rao said some people may be more predisposed to problems with the pars. Once a stress fracture occurs, he said, it can be very hard to heal.

However, changing attitudes of coaches and trainers is difficult, said Michael Reed, PhD, a physical therapist who specializes in the spine.

Part of the problem is the exercise is effective at strengthening muscles.

"The problem is, it can be very risky," said Reed, who practices at the Hospital for Special Surgery Spine and Sport in Jupiter, Fla. "Even the best form will not protect you."

Reed said he doubts many parents know how risky squats are. He said they probably rely on coaches and trainers who don't fully understand the risks.

Reed said squats also pose risk for older adults, but the biggest concern is in people who are skeletally immature.

Indeed, squats are a part of training for many high school sports, added McClellan. Many kids start doing the exercises by age 13.

He said he has seen more than 500 kids with pars fractures and often they remember hurting themselves doing squats.

Invariably, coaches will blame the injury on bad form, he said. Now there is evidence that even good form puts the spine at risk, he said.

Once a pars fracture occurs, the chance of it healing is as low as 2%, he added.

Many of those people eventually will develop degenerative disc problems and a lifetime of low back pain, he said.

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