October 2019

Extra Cushioning May not Help Shoes Prevent Injuries

Figure 1. From left to right, the women’s minimal, traditional, and maximal shoes used in this study (size 8.0) from the back (A) and side (B). Reprinted from Journal of Science and Medicine in Sport; available online 13 August 2019; Hannigan JJ and Pollard CD. Differences in running biomechanics between a maximal, traditional, and minimal running shoe. Copyright 2019, with permission from Elsevier.

By Nicole Wetsman

While innovations in running shoes have helped everyone from top athletes to casual joggers push the boundaries of speed, efforts to determine the characteristics of shoes that will help reduce injury risks are more elusive. In his lab at San Jose State University, JJ Hannigan, PhD, ATC, CSCS, is working to understand the way different levels of cushioning affect gait and running mechanics—which might hint at how they affect injuries.

In a recently published study in the Journal of Science and Medicine in Sport,1 Hannigan found few differences between the ground reaction forces in runners’ using maximal, traditional, and minimal running shoes (see Figure 1). However, runners wearing maximal shoes had increased eversion, which might signal increased injury risk.

This new study builds on two prior investigations of maximal running shoes. “The first was a simple study, with two visits,” Hannigan said. “We had participants run in a maximal shoe, which they had never run in before, and then run in a regular shoe.” Fifteen female runners participated in that study, which showed that maximal shoes gave runners higher impact forces than regular shoes—which was surprising, he said, as he had hypothesized that extra cushioning would decrease impact forces.2

In response, they ran the second study, which gave runners—who were not used to a maximal shoe—a period of transition. “We thought, maybe they needed more acclimation to the shoe,” Hannigan said. In addition, the two shoe types were from the same manufacturer, and were identical apart from the stack height of the shoe. Even with a 6-week acclimation period, there were still higher impact forces found with the maximal shoe.3

In the latest study, they added analysis of a minimal running shoe in addition to the maximal and normal shoes. The shoes were all from the same manufacturer, and the only variation was in stack height (see Figure 1). Three-dimensional kinematic data and data from force plates was collected on 20 runners as they ran in each of the 3 types of shoes; no differences between the ground reaction forces in each condition were shown.

The results indicate that the differences in ground reaction forces and impact seen before might not be due to the amount of cushioning, but could be caused by other variables on the shoes, Hannigan said.

“It could be the midsole, the design, the firmness—maybe one future study could compare different types of maximal shoes,” he said.

The increased eversion seen in the maximal shoe also pointed to possible areas of concern. “It may increase the risk of injury. We’ve found this now in a few maximal shoes. It may be that runners are further off the ground, and finding it harder to re-invert during their stance phase,” Hannigan said.

Hannigan’s line of research shows how little is still known about the way different types of running shoes affect factors relevant to injury risk. “The research is still inconclusive,” he said. In the meantime, he recommends that runners use a middle ground shoe—and one that is consistent with their natural running pattern. “Runners have a prefered way that they want to move. Shoes should not get in the way of that.”

In addition, one of the biggest ways to reduce injury has nothing to do with shoes, and instead leans on load management and ensuring athletes don’t ramp up their activity and mileage too fast. “Shoes can only do so much. The pendulum keeps swinging. We went to a minimal shoe, and thought that was the answer…now the pendulum is swinging back the other way to maximal shoes,” Hannigan said. “In my opinion as a shoe researcher, we’re not going to create the perfect running shoe to prevent injuries.”

Nicole Wetsman is a freelance writer in New York City.

REFERENCES
  1. Hannigan JJ and Pollard CD. Differences in running biomechanics between a maximal, traditional, and minimal running shoe. J Sci Med Sport. 2019;pii: S1440-2440(19)30473-6.
  2. Pollard CD, Ter Har JA, Hannigan JJ, Norcross MF. Influence of Maximal Running Shoes on Biomechanics Before and After a 5K Run. Orthop J Sports Med. 2018;6(6):2325967118775720.
  3. Hannigan JJ, Pollard CD. A 6-Week Transition to Maximal Running Shoes Does Not Change Running Biomechanics. Am J Sports Med. 2019;47(4):968-973.

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