Running: barefoot vs. cushioned shoe

The style of your running shoes isn't just making a fashion statement. It may be controlling the way you run and setting you up for injuries down the road.

That's what researchers at the University of Kansas Hospital found when they put a dozen high school athletes through their paces on a treadmill. When the teens ran barefoot or in flat-soled racing shoes, they generally landed on the front halves of their feet, the researchers said. But when the young athletes put on standard-issue running shoes with thick, cushioned heels, they instantly switched to a radically different gait, striking the treadmills with their heels.

Although there is no direct evidence that landing on your heels leads to long-term injury, some experts say that running this way may over time increase wear and tear to knees and hips.

"It may be more natural to land on your forefoot. It's uncomfortable to land on your heel," said Scott Mullen, a University of Kansas sports medicine specialist who co-authored the study. "But there's something in the makeup of the [cushioned] shoe that promotes that kind of heel strike."

Mullen, a marathoner and triathlete, put the teens on a treadmill to add some perspective to the growing reaction among runners against thick-heeled shoes. In fact, the relative merits of different shoe soles have become regular topics of debate in recent years.

Barefoot running or running in "minimalistic" shoes with as little as a third of an inch between the sole of the foot and the ground has become popular as a more "natural" way to run. The idea was promoted by the 2009 bestseller "Born to Run," about the Tarahumara Indians of Mexico, who run for hundreds of miles without injury, wearing thin-soled sandals.

The injury-prevention message has also been fueled by research, including a Harvard study from 2010 that looked at runners in Kenya. The researchers found that even on hard surfaces, barefoot runners who landed on their forefeet gave their bodies less of a jolt than runners who wore shoes and landed on their heels.

Mullen wanted to see how the different kinds of shoes affected young athletes who hadn't settled on a running style.

His subjects were six boys and six girls ranging in age from 13 to 18 who were recruited from local track teams. They took turns on a treadmill that was surrounded by 12 infrared cameras recording motion in three dimensions from markers attached to their feet, ankles and knees.

Each did short runs at different speeds going barefoot, wearing the conventional cushioned-heel running shoes most of them used for training or wearing racing flats with little or no heel elevation.

In the cushioned shoes, the runners landed on their heels about 70 percent of the time. But in track flats, they hit heel-first less than 35 percent of the time, and when barefoot just 30 percent of the time.

"Simply by changing their footwear, the runners' foot strike would change," Mullen said. "When they ran in the cushioned heel of an average running shoe — even when running a five-minute mile —the athletes landed on their heel first."

Although no studies have tied particular running styles to greater risk of injuries, heel-strike running does put more stress on hips and knees, he said.

"I certainly think it's a reasonable conclusion that if you decreased the forces when running it would be for the better," he said.

But older, seasoned runners who've been running in comfy, cushioned shoes for some time shouldn't make a quick switch to minimalistic.