Runners experienced a higher impact peak and an increased loading rate while wearing maximal running shoes, which may increase their risk for injuries such as plantar fasciitis and tibial stress fractures, researchers suggest.

In their study, published in The Orthopaedic Journal of Sports Medicine, researchers in the Functional Orthopedic Research Center of Excellence (FORCE) Lab at Oregon State University—Cascades compared the biomechanics associated with “maximal” and “neutral” running shoes in tests with 15 female runners.

Maximal running shoes are designed to contained increased cushioning, particularly in the forefoot region of the midsole.

Runners wearing maximal shoes, the researchers wrote, have reported feeling the extra cushion after running 2 to 3 miles. As a result, the researchers did not expect to find increases in impact peak or loading rate in runners wearing maximal shoes, the researchers explain, in a media release from Oregon State University.

As part of the FORCE study, researchers evaluated the impacts on runners’ feet and legs before and after a simulated 5,000 meter (about 3 miles) run on a treadmill. Each subject wore a neutral running shoe (New Balance 880) for one test and then, after a 7 to 10-day waiting period, repeated the procedure with a maximal shoe (Hoke One One Bondi 4).

In each test, 3D movements and forces were measured by monitoring reflective markers placed on the runners’ shoes and legs and by having the subjects run over a “force plate” that recorded the forces being applied as the runner’s foot hit the surface.

“We were surprised by these results,” says Christine Pollard, director of the FORCE Lab and an associate professor of kinesiology, per the release.

“We thought we would see the opposite. Typically, increased cushioning results in a reduction in the impact peak and loading rate of the vertical ground reaction force. We suspect that the large amount of cushioning across the entire midsole caused the runners to rely more on the shoe than on their own internal structures to attenuate these forces,” adds Pollard, also a licensed physical therapist.

The study also evaluated the degree of “peak eversion,” the outward turning of the foot, a factor associated with injury risk. The researchers found no difference between the maximal and neutral shoes.

Pollard expects that a study with male runners might produce different results, she states in the release. “We know that gender differences in running biomechanics do exist,” she adds.

[Source(s): Oregon State University, Science Daily]