Runners exhibited increased impact forces and loading rate when running in a maximal versus neutral shoe, with an associated increased risk of running-related injuries, found a small Oregon State University-Cascades study.
Researchers in the Functional Orthopedic Research Centre of Excellence (FORCE) Lab compared the biomechanics associated with "maximal" and "neutral" running shoes in tests with 15 female runners. The study concluded that runners experienced a higher impact peak and increased loading rate with the "maximal" shoes. Increases in both factors are associated with a greater likelihood of injury, such as plantar fasciitis and tibial stress fractures.
The study is believed to be the first rigorous analysis of impacts associated with maximal shoes.
Maximal running shoes feature increased cushioning, particularly in the forefoot region of the midsole, and have gained popularity since being introduced in 2010. More than 20 varieties of maximal shoes are on the market.
Runners wearing maximal shoes, the researchers wrote, have reported feeling the extra cushion after running two to three miles. As a result, the researchers did not expect to find increases in impact peak or loading rate in runners wearing maximal shoes.
In the FORCE Lab study, researchers evaluated the impacts on runners' feet and legs before and after a simulated 5km run on a treadmill. Each subject wore a neutral running shoe (New Balance 880) for one test and then, after a seven 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," said Christine Pollard, director of the FORCE Lab and an associate professor of kinesiology. "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."
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.
The research is a first step in gathering evidence on the effects of maximal running shoes on runners' injury risks, said Pollard, who is also a licensed physical therapist. Maximal shoes are becoming very popular, but without controlled studies, clinicians have been unable to make science-based recommendations to runners.
Pollard said she expects that a study with male runners might produce different results. "We know that gender differences in running biomechanics do exist," she added.
Abstract
Background: Lower extremity injuries are common among runners. Recent trends in footwear have included minimal and maximal running shoe types. Maximal running shoes are unique because they provide the runner with a highly cushioned midsole in both the rearfoot and forefoot. However, little is known about how maximal shoes influence running biomechanics.
Purpose: To examine the influence of maximal running shoes on biomechanics before and after a 5-km (5K) run as compared with neutral running shoes.
Study Design: Controlled laboratory study.
Methods: Fifteen female runners participated in 2 testing sessions (neutral shoe session and maximal shoe session), with 7 to 10 days between sessions. Three-dimensional kinematic and kinetic data were collected while participants ran along a 10-m runway. After 5 running trials, participants completed a 5K treadmill run, followed by 5 additional running trials. Variables of interest included impact peak of the vertical ground-reaction force, loading rate, and peak eversion. Differences were determined by use of a series of 2-way repeated-measures analysis of variance models (shoe × time).
Results: A significant main effect was found for shoe type for impact peak and loading rate. When the maximal shoe was compared with the neutral shoe before and after the 5K run, participants exhibited an increased loading rate (mean ± SE: pre–maximal shoe, 81.15 body weights/second [BW/s] and pre–neutral shoe, 60.83 BW/s [P < .001]; post–maximal shoe, 79.10 BW/s and post–neutral shoe, 61.22 BW/s [P = .008]) and increased impact peak (pre–maximal shoe, 1.76 BW and pre–neutral shoe, 1.58 BW [P = .004]; post–maximal shoe, 1.79 BW and post–neutral shoe, 1.55 BW [P = .003]). There were no shoe × time interactions and no significant findings for peak eversion.
Conclusion: Runners exhibited increased impact forces and loading rate when running in a maximal versus neutral shoe. Because increases in these variables have been associated with an increased risk of running-related injuries, runners who are new to running in a maximal shoe may be at an increased risk of injury.
Authors
Christine D Pollard, Justin A Ter Har, JJ Hannigan, Marc F Norcross
[link url="http://today.oregonstate.edu/news/‘maximal’-running-shoes-may-increase-injury-risk-some-runners"]Oregan State University material[/link]
[link url="http://journals.sagepub.com/doi/10.1177/2325967118775720"]Orthopaedic Journal of Sports Medicine abstract[/link]