When Vibram USA reached a $3.75 million settlement on a class action lawsuit last week, much of the commentary around the deal centered on the question of whether or not the shoes come with an injury risk.
The suit alleged that Vibram, the Concord-based company that makes the wonky-looking FiveFingers toe shoes some runners have taken to in the past few years, falsely advertised that its minimalist running shoe carries health benefits. Consumers said Vibram couldn’t prove it. Presto—there’s your class action suit.
Vibram says it didn’t do anything wrong, but that it settled to nip the suit in the bud rather than watch it drag on and grow more expensive. Take that as you may; at the end of the day, Vibram is paying up and stripping mention of those health benefits from its advertising, at least for now.
But saying minimalist shoes cause injury might be a little misplaced. There isn’t strong evidence either way just yet. It’s probably more fair to say that the transition from regular running shoes to those like the FiveFingers brand is what actually poses a threat.
I spoke with Harvard Medical School professor Dr. Irene Davis, the director of the Spaulding Rehab Network’s National Running Center in Cambridge. Worth noting: Davis has previously participated on a Harvard study with other scientists which was partially funded by Vibram. That study did not recommend any particular running style, nor did it recommend any particular type of running shoe. She has since worked on other studies that were not backed by Vibram, and she declined to specifically discuss the Vibram case.
Davis says transition is the key word when talking about minimalist shoes and health effects. The shoes, with little in the way of sole padding, encourage runners to land on the balls of their feet. She notes that this is more natural than landing on the heel, saying when running barefoot people tend to do so in an effort to protect their heels.
However, running shoes have grown increasingly padded as recreational running has picked up in the past 40 years. (She says that if you look at sneakers from the 1970s or before, many of them could be considered more minimal than even some of today’s minimalist products.) Today, perhaps as a result of the added cushioning, about 90 percent of runners say they land on their heels, Davis says.
So when somebody who’s used to landing on their heel abruptly switches to the ball of their foot, their body just might not be used to the different kind of impact. Landing on the heel, Davis says, creates an impact that research has shown is related to common running injuries, and puts a load on the knee—what she says is the most common site for running injuries.
Landing slightly on the front part of the foot eliminates that impact but requires more work from the calves. Davis says she believes calves should be taking more of the load. Ball-of-the-foot impact also puts below-knee body parts like the shins and foot arches at risk. Davis says it’s important for runners switching to a minimalist shoe to make sure they strengthen those parts of the body before they make the switch.
“People tried to jump on (the minimal shoe trend) too quickly,” Davis says.
None of that really gets Vibram off the hook for alleged false advertising. The gist of the complaint is that Vibram didn’t cite scientific evidence claiming minimalist models reduce injury, according to Runner’s World—evidence that does not yet exist. But it is an important caveat when discussing the effects the shoes have on runners. There may or may not be a health benefit—we don’t know yet—but a poor transition is definitely a health threat.
There’s a space between truly minimalist shoes and padded sneakers. Some companies make shoes that look minimalist but actually have some light padding on the sole. Davis says that even with just a bit of padding, research shows runners opt to land on their heels. “That’s probably not a good thing,” she says.
Davis points to a recent study that tracked runners over a period of 12 weeks in the three different types of shoes—regular running shoes, minimalist shoes, and partially minimalist shoes. Of those, runners with parially minimalist shoes reported the most injuries while those in regular shoes faired the best.
That the study only covered a 12-week period might signal that the injuries incurred came as a result of the transition to those shoes, Davis says.
She holds that minimalist shoes could still mitigate running injuries if the runner prepares themselves properly. However, Davis says, “If runners are going to continue to land on their heels, they should make sure they have adequate cushioning and that they replace their shoes often.”