Cushioned Heel Running Shoes May Alter Adolescent Biomechanics, Performance

Today's running shoes may alter adolescent runners' biomechanics—the forces exerted by muscles and gravity on the skeletal structure—and diminish performance. "The modern running shoe typically features a large cushioned heel intended to dissipate the energy at heel strike to the knees and hips," according to Scott M. Mullen, MD, and E. B. Toby, MD, from Kansas City, Kansas.

The investigators sought to determine the effect of shoes on running biomechanics in 12 adolescent competitive athletes from local track teams, specifi cally, whether running style was affected due to shoewear only. Mullen and Toby asked the study participants to run on a treadmill in large heel trainers, track fl ats, and without any shoes (barefoot) at four different speeds. Biomechanics, including stride length, heel height during posterior swing phase, and foot/ground contact, were measured with a motion capture system.

"Running barefoot or running in less of a running shoe (toe shoes, for example) is a newer trend," Mullen stated. "What we were trying to evaluate is whether or not the foot strike would change in an adolescent—who doesn't yet have a permanently established gate—when they changed their shoe or running speed."

The researchers found that shoe type dramatically altered running biomechanics in the adolescent runners. When wearing cushioned heel trainers, the athletes landed on their heel 69.8% of the time at all speeds. With the track fl ats, the heel was the first point of contact less than 35% of the time; and when barefoot, less than 30% of the time. Shoes with cushioned heels promote a heel-strike running pattern, whereas runners with track fl ats and barefoot had a forefoot or mid-foot strike pattern.

"What we found is that simply by changing their footwear, the runners' foot strike would change," Mullen observed. "When they ran in the cushioned heel or an average running shoe—even when running a 5-minute mile—the athletes landed on their heel first."

Many adolescent runners train in cushioned heels and compete in track spikes, "which may give them less of a (performance) advantage" in competition, said Dr. Mullen. As a 2010 study found that heel strike running distributes more energy to hips and knees, running in fl atsoled shoes that promote a forefoot strike may "present a healthier foot strike for runners over a lifetime, possibly resulting in fewer hip and knee problems," he concluded. More research is needed to determine the effects of shoes on foot strike.