When Bad Form Is A Real Pain

Motion analysis is helping doctors pinpoint postural sources of aches and injuries

When Stephanie Kays watched a videotape in slow motion of herself running, the reason for the knee pain that had plagued her for the past year was clear. "You could see how my legs rolled slightly inward when I struck the ground, so I was almost knock-kneed," says Kays, a 24-year-old speech pathologist in Madison, Wis., who runs five times a week to stay fit. The physical therapist who filmed her running on a treadmill, using several cameras positioned at various angles, determined that muscle weakness in her hips was causing excessive leg rotation and prescribed stretching and strengthening exercises to correct it. Nine weeks later, Kays reports that she is "virtually pain-free."

Motion analysis is the latest movement in treating sports injuries and other common musculoskeletal aches and pains. Orthopedists and physical therapists are using everything from basic video equipment to sophisticated infrared motion sensors and gravitational force plates to deconstruct their patients' movement patterns and determine whether bad form is causing their discomfort. "No matter how strong or fit you are, a flaw in technique over time will predispose you to injury," says Dr. Edward Laskowski, co-director of the Mayo Clinic Sports Medicine Center in Rochester, Minn., which has its own motion-analysis laboratory.

Whether you're playing squash or mowing the lawn, if you're off-kilter because of poor posture or strength imbalances, you can overburden bones, joints, or muscles. "It's like having a tire out of alignment on your car," says Jody Jensen, associate professor of kinesiology and health education at the University of Texas. "You don't get a smooth ride, and you start seeing unusual wear patterns after a while." Muscle inflammation, strains and tears, stress fractures, and osteoarthritis are often the result. Motion analysis tries to head off such injuries by helping you correct your inefficient and possibly damaging movement patterns.

Elite athletes have long relied on the discerning eye of professional coaches to critique their form and help prevent injury. But within the past decade, biomechanics researchers have come up with more objective and precise ways to analyze movement. For example, motion-analysis software superimposes video on a grid to determine joint angles and can calculate such things as torque and acceleration. Various devices measure the force with which your feet strike the ground, how rapidly electrical signals transmit through your muscles, and how much oxygen you use during an activity.

EXTENSIVE WORKUP. Fees vary from $200 to $5,000, depending on the sophistication of the analysis and extent of the treatment -- and they're not usually covered by health insurance. "A lot of times, an experienced specialist can figure out what's going on without you having to be hooked up to too many devices," says Bryan Heiderscheit, assistant professor of orthopedics and rehabilitation at the University of Wisconsin. His patient, Kays, needed only to be videotaped to identify her problem.

But Margaret Colvin required a more extensive workup when she visited the Running Injury Clinic at the University of Delaware in Newark to find out what was causing persistent bursitis in her hip. Colvin, a 42-year-old high school counselor, walked and ran on a force plate that measured how hard and where her feet were striking the ground. She also had reflective markers attached to various points on her body, which a camera detected, digitized, and flashed on a large computer screen in front of her.

The resulting real-time, 3D image of her movements is akin to what animators at Pixar Animation Studios (PIXR ) used to create movies such as Toy Story and Monsters Inc. The technology not only allows motion specialists to pinpoint irregularities in gait and posture but also "gives the patient the opportunity to visualize and correct what they are doing wrong, much like biofeedback," says Irene Davis, associate professor in the department of physical therapy at the University of Delaware. Six months after learning a series of strengthening exercises, as well as how to run in a way that does not overload her hip, Colvin says she's training for a triathlon.

FINDING A SPECIALIST. There is no comprehensive resource for finding a motion-analysis specialist. The Gait & Clinical Movement Analysis Society Web site (gcmas.org) lists affiliated institutions, but many treat only children or people with severe disabilities. You can always check with a recreational running, cycling, or golf club in your area. Members of those groups usually know of local movement specialists. Podiatrists, chiropractors, and licensed athletic trainers might offer rudimentary motion analysis, but clinics with the most advanced equipment tend to be staffed by orthopedists and physical therapists.

When you go for your appointment, take a pair of well-worn shoes. The movement specialist will want to study the wear patterns on your soles. Be prepared to give a detailed account of your daily physical activities and past injuries. You will also be measured with the precision of a couturier to see if you have any length discrepancies, such as one leg that's shorter than the other. What follows depends on the complexity of your problem -- and the limitations of your wallet. Because many motion-analysis clinics are affiliated with universities, you might be able to enroll in a research study. That way, you'll learn to perfect your form for free.

By Kate Murphy

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