Jan. 7, 2010 — Compared to running barefoot, running inconventional running shoes increases stress on the knee joints up to 38%,according to a new study.
”There is an increase in joint torque that may be detrimental,” says D.Casey Kerrigan, MD, the lead author of the study, published in PM&R: TheJournal of Injury, Function and Rehabilitation.
Joint torque is a measure of how much a force causes the joint torotate.
But Kerrigan is not advocating that runners take up barefoot running — justthat her findings may be a reason to redesign running shoes. Kerrigan, formerlychairwoman and professor of physical medicine and rehabilitation at theUniversity of Virginia, Charlottesville, now heads JKM Technologies and isdesigning a running shoe.
At least one podiatric specialist calls the study finding ”much ado aboutnothing.”
Running Shoes Study: Details
Kerrigan’s team evaluated 68 runners — 37 women, average age 31, and 31men, average age 36 — who ran at least 15 miles a week. None hadany history of musculoskeletal injury.
Participants ran barefoot on a treadmill and then in a running shoe: theBrooks Adrenaline.
Kerrigan’s team observed how each condition, barefoot and shod, affected thejoints of the hip, knee, and ankle.
Compared to running barefoot, the researchers found running in runningshoes increased stress on the lower extremities. They found a 54%increase in the hip internal rotation torque and a 36% to 38% increase in kneetorque. Is that increase mild, moderate, worrisome? “We don’t know,”Kerrigan tells WebMD. “We just know it’s an increase.”
She attributes the increased stress to the characteristic design of themajority of running shoes, including an elevated heel and increased material inthe midsole arch.
Providing this cushioning in the heel, she suspects, counteracts the body’snatural response to compensate for the torque associated with impact.
The increases found in her current study are higher than when she comparedbarefoot walking to walking in high heels. The high-heel shoes increased kneejoint torque by 20% to 26%, she says.
Running Shoes Study: Analysis
Some torque on the knee is normal, of course. “What we are saying is, thereis an increase over what would be experienced just walking around,” Kerrigansays.
Her concern is that the excess stress may contribute to knee osteoarthritis, although thestudy did not look at a link between running shoes and injury or running shoesand the development of arthritis.
She isn’t suggesting barefoot running — a trend that’s picked up steam inthe past year or so — is necessarily better than running in athletic shoes,she says.
Running Shoes Study: Other Opinions
”It’s much ado about nothing,” says Bruce Williams, DPM, past president ofthe American Academy of Podiatric Sports Medicine and a spokesman for theAmerican Podiatric Medical Association, of the study results.
“She showed there was an increase in joint forces, but that’s it,” saysWilliams, a podiatrist in Valparaiso, Ind., and a runner. There was no linkshown between running shoes and running injuries, nor with development ofarthritis — both beyond the scope of the study.
The bulk of research studies have found that runners don’t have a higherincidence of knee osteoarthritis than the general population, Williams tellsWebMD.
In one study, for instance, German researchers evaluated 20 former elitemarathon runners and compared them to the general population, looking forarthritis. They found that knee osteoarthritis was rare in the formermarathoners, publishing the result in the journal Orthopade.
Ideally, Kerrigan’s team should have looked at many different shoe types,says Joseph Hamill, PhD, professor of kinesiology and director of theBiomechanics Laboratory at the University of Massachusetts, Amherst, who hasresearched the biomechanics of running shoes. “For example, a racing flat hasvery little in the way of cushioning and is almost like running barefoot,”Hamill says.
Running Shoes Study: Industry Input
In an email response, Tiffany Herman, a spokeswoman for Brooks Sports, whichmakes running shoes, says: ”We value the results of this study and are inactive research and development on many unique performance running footwearsolutions at Brooks.”
”This includes styles that enhance the natural motion of the foot and bodywhile offering protection from weather conditions, road debris, and individualbiomechanical variances.”
Running Shoes: What to Buy?
So what’s a runner to wear — or not wear? “Nobody should take the messagethat being barefoot is better than wearing any type of shoe whatsoever,” saysWilliams of the new study.
Kerrigan, too, says her research isn’t a vote for the barefoot running trend– nor for giving up running.
“If you are happy with your running shoes, you don’t necessarily have tochange them,” Williams says. But if you have an injury, he suggests consultinga sports podiatrist and getting advice about the best shoe features foryou.
”I would suggest runners try a number of different types of shoes untilthey find one that they like,” Hamill says. “Also, buy two or three pairs ofshoes and rotate them each day.”