Are you a runner who shelled out $100 or so for a pair of those funny-looking barefoot shoes, the ones with the individual toe-holders? Were you swayed by claims that your shoes were scientifically proven to "make your feet stronger" and healthier"?

Bad news: you were duped.

Vibram, the company that manufacturers FiveFinger shoes, settled last year a multi-year, class-action lawsuit brought by customers who were, to put it mildly, dubious of the company's claims that barefoot running shoes could improve health. The shoe manufacturer agreed to pay out as much as $3.75 million to anyone who purchased a pair of their finger-shoes since March 2009 and who filed as part of the class action lawsuit by May 2014.

Perhaps more significantly, Vibram had to hugely dial back the health claims it's made for years about the benefits of running in its minimalist shoes, which are meant to mimic running barefoot.

"Vibram will not make...any claims that FiveFingers footwear are effective in strengthening muscles or preventing injury unless that representation is true, non-misleading and is supported by competent and reliable scientific evidence," the federal settlement says.

The reliable scientific evidence they require? For Vibram's barefoot shoes, it doesn't exist.

Americans have purchased more than 70 million pairs of barefoot shoes

Sales of Vibram's shoes have skyrocketed lately: one court filing notes that the company has seen an average of 300 percent annual sales growth over the past six years. In 2012, total sales of their FiveFinger shoes were approaching 70 million.

Some of that growth was likely driven by a book that came out in 2009 called Born to Run. There, Chris McDougall wrote about a little-known Indian tribe in Mexico who seemed to have an unusually strong ability to run exceptionally long distances. They also happened to run without shoes.

Thus McDougall's book became a so-called "barefoot manifesto" for runners — although he now says that wasn't totally the point. "People refer to it as a 'barefoot manifesto,'" McDougall told Deadspin in an interview yesterday. "It's not that at all. It's not that I'm championing bare feet; it's just that I'm questioning running shoes — because really the burden of proof is on the running shoe."

Barefoot runners do run differently

The biggest change that barefoot shoes make has to do with when the foot hits the ground. Most runners are heel-strikers — their heel hits the ground first, followed by the rest of the foot. But barefoot runners, research suggests, run differently: they're more likely to be fore-foot strikers, landing on the ball of their foot with the rest of the foot following. You can see the difference between the two in these videos from Harvard researchers:

Some sports researchers argue that landing on the front of the foot can help protect against injuries, because it tends to be a slightly lower-impact encounter with the ground. It "may protect the heel and lower limbs from some impact-related injuries," a 2012 article in the journal Sports Health concluded. And studies do show that the Vibram shoes are pretty good at mimicking the experience of running completely barefoot.

But to switch to the fore-foot pattern that barefoot shoes encourage, there's a trade-off: running with a whole lot less support than traditional shoes offer.

But do they run with fewer injuries?

Vibram has attached a laundry list of health claims to its shoes, detailed in a February 2013 legal complaint:

(1) strengthen muscles in the feet and lower

legs, (2) improve range of motion in the ankles, feet, and toes,

(3) stimulate neural function important to balance and agility,

(4) eliminate heel lift to align the spine and improve posture,

and (5) allow the foot and body to move naturally. At various

times, defendants' website added that wearing FiveFingers would

improve proprioception and body awareness, reduce lower back pain

and injury, and generally improve foot health.

Podiatrists beg to differ. The American Podiatric Medicine Association put out a policy statement back in November 2009 — which they still stand by today — saying that "research has not yet adequately shed light on the immediate and long-term effects of this practice."

"Barefoot running has been touted as improving strength and balance, while promoting a more natural running style," the podiatrists' statement continues. "However, risks of barefoot running include a lack of protection, which may lead to injuries such as puncture wounds, and increased stress on the lower extremities."

There's just not much research right now on how barefoot shoes affect runners. The ones that exist are pretty tiny, like a 2011 study of two very experienced runners who developed stress fractures after switching to Vibram shoes.

Another study, also in 2011, had a slightly larger group of runners switch to Vibram's shoes. Researchers at Brigham Young University studied a group of 36 runners who ran into traditional shoes, and transitioned half of them into Vibram shoes.

They showed that, after 10 weeks of running in the two types of the shoes, about half of the runners who had transitioned to Vibrams had developed an inflammation of their bone marrow, which can be a precursor to a stress fracture. Only one person in the control group had seen a similar change.

Aside from these two studies, there just isn't much research on injury rates in traditional versus barefoot running shoes. Which is why Vibram is going to have to back off its advertising claims of benefits — and shell out a few million dollars to the runners it did promise healthier feet.

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