BIOMECHANICS AND INJURY: WHAT’S WRONG AND HOW TO CHANGE IT

While training for the Marine Corps Marathon, Margaret Colvin, 48, of Rehoboth Beach, Delaware, developed patellofemoral pain syndrome (a.k.a. runner’s knee)—unfortunate, but not uncommon. Her luck improved when she was referred to the Running Injury Clinic at the University of Delaware. There she met with Irene Davis, Ph.D., a physical therapist and researcher in the field of gait retraining, a method of rehabilitating running injuries by correcting flaws in a runner’s stride.

Using video analysis of Colvin’s stride, Dr. Davis looked for biomechanical abnormalities that could be causing the pain. Dr. Davis found that Colvin’s thigh was rotating internally during ground contact due to weakness in her hips. But instead of just giving her hip-strengthening exercises, Dr. Davis also helped her modify her running mechanics to reduce the stress on her knee.

To assist Colvin in the gait-retraining process, sensors were attached to her leg. These sensors produced a graph on a video monitor that she could watch and manipulate while running on a treadmill at the clinic. Davis taught Colvin how to activate her hip abductors and hip external rotators to achieve the optimal stride.

For several weeks Colvin was allowed to run only at the clinic.

Using the instant feedback system, she was able to strengthen her hips and gradually reprogram the neuromuscular patterns that controlled her stride. When her new gait felt natural, she resumed training on her own. Two years later, Colvin says her corrected stride remains intact and she has had no more knee pain.

Dr. Davis hopes that gait retraining will soon become standard treatment for injured runners. “Abnormal running mechanics are a factor in many running injuries, and in most cases these flaws can be corrected,” says Dr. Davis. But at present, few professionals who treat injured runners suggest gait retraining because of the prevailing wisdom that a person’s running gait is too “automatic” to be changed. “Most of us have a stride that’s natural to our body—the stride that’s best for us,” says Alan Hreljac, Ph.D., a professor of biomechanics who studies running injuries at California State University in Sacramento.

While many physical therapists try to correct stride flaws indirectly by prescribing strengthening and stretching exercises designed to correct muscle imbalances, proponents of gait retraining believe that’s just the first step. Such measures are “necessary, but seldom sufficient,” says Dr. Davis, because stride flaws result not just from muscle imbalances but also from ingrained neuromotor patterns that are unlikely to change except through conscious practice.

“We’re not talking about drastic changes,” says Bryan Heiderschiet, Ph.D., a physical therapist who practices gait retraining at the Runner’s Clinic of Des Moines University. For example, some running injuries are associated with a slight forward tilt of the pelvis that can be easily corrected by learning to engage the deeper abdominal muscles while running. It’s a small tweak—yet it won’t happen without conscious effort.

There are two key limitations of gait retraining. First, “It requires expertise in running mechanics and the etiology of running injuries,” says Dr. Davis. In other words: Don’t try this at home. You need the guidance of a knowledgeable professional.

Also, it’s not appropriate for general injury prevention, but only for rehabilitating and preventing the recurrence of specific injuries. “If you try to ‘fix’ your stride when you’re uninjured,” says Dr. Davis, “it’s more likely that you’ll cause an injury than prevent one.”

Find Your Flaw

Research in the field of gait retraining has identified four common stride flaws that are associated with specific running injuries. If you are repeatedly hampered by any of the injuries listed below, you may be a good candidate for gait retraining. Once a flaw has been detected by a gait-analysis expert, he or she can help you fix your form.

Injuries: Patellofemoral pain syndrome, iliotibial band friction syndrome

Stride Flaw: Thigh internally rotates during ground contact

Form Fix: Actively engage the muscles of the buttock and the outside of the hip while your foot is in contact with the ground.

Injuries: Patellofemoral pain syndrome, plantar fasciitis, Achilles tendinosis

Stride Flaw: Overpronation of the foot

Form Fix: Push off with your big toe. Concentrate on keeping your knees pointing straight ahead during ground contact.

Injuries: Patellofemoral pain syndrome, iliotibial band friction syndrome

Stride Flaw: One hip drops when opposite foot is on the ground

Form Fix: Increase step width. Practice running along a straight line, making sure your feet land evenly on either side of it.

Injuries: Shinsplints, stress fractures

Stride Flaw: Overstriding (severe heelstrike)

Form Fix: Increase your stride frequency by increasing your steps per minute without increasing your pace. Also, lean forward very slightly at the trunk.