Runners spend $20 billion annually on running shoes, with many lacing up pairs that can cost as much as $200. But is all this fancy footwear really a good investment? A new musculoskeletal study finds that running with running shoes exerts significantly more stress on key joints than running barefoot, potentially increasing a runner’s risk of developing disabilities such as osteoarthritis in the knees.

The key culprit is contemporary running-shoe design, which interferes with the body’s natural ability to absorb forces through the foot, says lead author Casey Kerrigan, who published the study in the journal PM&R: The Journal of Injury, Function and Rehabilitation. Most troubling is the finding that running with running shoes leads to a 38% increase in pressure to a part of the knee — the medial tibiofemoral compartment — particularly prone to joint degeneration.

Three Key Joints Feel The Pressure

“It was surprising that the percent increase was so high with running shoes,” says Kerrigan, an expert in biomechanics, human movement and gait who has a medical degree from Harvard University. “We really didn’t see those dramatic increases in walking.”

Overall, the study finds that while today’s running shoes do a good job of protecting the foot, wearing them dramatically increases pressure in three lower-extremity joints — the hip, knee and ankle — when compared to running barefoot. For example, researchers note that wearing running shoes while running leads to an average 54% increase in what’s called hip internal rotation torque, pressure that may increase the risk of osteoarthritis in the hip joint.

To put things in perspective, walking in high heels — long considered a joint-busting exercise — increases knee joint torques (a pressure measurement) by no more than 26%, while the effect of running shoes on knee joint torques while running leads to up to a 38% increase, the researchers say.

With all the runner’s out there — the U.S. Bureau of Labor Statistics says more than 7% of the U.S. population regularly runs for exercise — the increased potential for osteoarthritis is a big concern. There’s no cure for the degenerative joint disease, the most common form of arthritis, which costs about $186 billion a year in the U.S. to treat. 

First Athletic Shoe In 1972

So why is it that with the first athletic shoe invented in 1972, designers nearly four decades later still haven’t figured out how to make a shoe that can spare us from all these joint problems? Despite increasingly expensive shoes, there’s been little change over the years in the rate of injury of runners. 

Kerrigan argues that despite recent advances in gait analysis, the increased understanding of biomechanics hasn’t yet been incorporated into shoe construction. While the cushion in the heel and the medial arch may keep the foot comfy in existing designs, they disrupt how the foot helps mitigate forces. 

When running barefoot, people typically come down on the heel but quickly roll over to the inside of their foot. “Running shoes typically inhibit your ability to do that,” says Kerrigan, who ran track in high school and college and continues to run today. “Ideally, what you want to do is enhance those abilities.”

Running barefoot, however, isn’t the answer, she says, unless you can run on grass with spongy topsoil underneath. “When you’re running on hard surfaces, you just don’t have that springy interface,” says Kerrigan, a former professor and chair of the department of physical medicine and rehabilitation at the University of Virginia. “Unfortunately, our feet haven’t evolved to accommodate hard surfaces.” 

Current Shoe Design Found Lacking

As chairman of the Charlottesville, Virginia-based “optimal” shoe-design firm JKM Technologies, it’s no shock that Kerrigan’s research finds faults with current running shoes. But it actually builds on loads of previous research suggesting there is something lacking in current running-shoe design.

“A lot of foot and knee injuries currently plaguing us are caused by people running with shoes that actually make our feet weak, cause us to over-pronate and give us knee problems,” Daniel Lieberman, a professor of biological anthropology, told the U.K. newspaper the Daily Mail earlier this year. “Until 1972, when the modern athletic shoe was invented, people ran in very thin-soled shoes, had strong feet and had a much lower incidence of knee injuries.”

In Kerrigan’s study, researchers looked at 68 healthy young adult runners (31 men and 37 women) who each run at least 15 miles a week. An integrated measurement system that included a specialized treadmill, computers, cameras and reflective markers placed on the runners’ “anatomical landmarks” calculated joint torques as they ran.

But as Kerrigan points out, there are limitations to this method: Researchers can estimate the net difference between the forces on either side of a joint, but not the actual joint-contact forces, the study says. “The only way would be to put a force transducer into a live joint,” says Kerrigan. “We haven’t been able to find any volunteers for that.”

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