Study Shows Running Shoes Exert More Stress on Knees and Hips Than Running Barefoot
Jan. 7, 2010 -- Compared to running barefoot, running in conventional 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: The Journal of Injury, Function and Rehabilitation.
Joint torque is a measure of how much a force causes the joint to rotate.
But Kerrigan is not advocating that runners take up barefoot running -- just that her findings may be a reason to redesign running shoes. Kerrigan, formerly chairwoman and professor of physical medicine and rehabilitation at the University of Virginia, Charlottesville, now heads JKM Technologies and is designing a running shoe.
At least one podiatric specialist calls the study finding ''much ado about nothing."
Running Shoes Study: Details
Kerrigan's team evaluated 68 runners -- 37 women, average age 31, and 31 men, average age 36 -- who ran at least 15 miles a week. None had any history of musculoskeletal injury.
Participants ran barefoot on a treadmill and then in a running shoe: the Brooks Adrenaline.
Kerrigan's team observed how each condition, barefoot and shod, affected the joints of the hip, knee, and ankle.
Compared to running barefoot, the researchers found running in running shoes increased stress on the lower extremities. They found a 54% increase in the hip internal rotation torque and a 36% to 38% increase in knee torque. 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 the majority of running shoes, including an elevated heel and increased material in the midsole arch.
Providing this cushioning in the heel, she suspects, counteracts the body's natural response to compensate for the torque associated with impact.
The increases found in her current study are higher than when she compared barefoot walking to walking in high heels. The high-heel shoes increased knee joint torque by 20% to 26%, she says.