I first heard about Born to Run, the Chris McDougall book that sparked the barefoot running craze, during my freshman year of college in 2012. At the time, before I got bogged down with trivialities like torn anterior cruciate ligaments (turns out those really matter), I was a running fiend.

I ran every day. On pavement, on dirt backroads, up mountains, on rocky paths along the Connecticut River: There was nowhere my trusty Adidas Kanadia Trail shoes couldn’t take me. I pushed aside the popular and academic rumblings about how barefoot running made for fewer injuries and went about my business.

But alas, age and misfortune make fools of us all. Following an injury and subsequent ACL reconstruction in my left knee two years later, I found myself unable to run at all—crippled with painful patellar tendonitis. Trying different sneakers didn’t work, running less didn’t work, and running off-road didn’t work. So I figured, “What the hell?”, and gave the barefoot running thing a shot.

I tried out my Vibram FiveFingers for the first time on a foggy morning running up Mount Flume on New Hampshire’s Franconia Ridge, reveling in the feeling of the woodsy path so close to my soles.

It was 2013, and the height of Vibram shoe craze. The minimalist, slipper-like foot sleeves flew off the shelves as runners and consumers alike hopped on board the barefoot train. I, too, was a willing passenger, hoping these shoes-that-weren’t-shoes might allow me to once again run in peace.

I ran with insatiable enthusiasm following my new acquisitions, liberated from laces and tight toe boxes. But romantic treks up wilderness peaks aside; perhaps I should’ve read the fine print first.

Two months later all I had to show for my efforts were shin splints and a bad temper. The muscles in the front of my lower leg screamed in pain, having been worked too much too fast.

This unfortunate occurrence, causal or not, sparked an obsession with why barefoot running didn’t seem to work for me. I was convinced Vibrams lay at the heart of my locomotor woes. So I read everything I could, starting with McDougall’s book, and dedicated the rest of my undergraduate career to the study of the foot, trying to figure out what went wrong.

Born To Run, McDougall’s exposé about the indigenous Tarahumara of Mexico, enigmatic ultramarathoners who wore the thinnest sandals, drew on research by human evolutionary biologist Daniel Lieberman at Harvard University, who claimed that our early human ancestors ran barefoot and that modern running shoes don’t really prevent injuries.

McDougall’s book and Lieberman’s research spurred shoemakers across the board to release dozens of minimalist shoes in the early 2010s. The industry landscape went from three companies in the minimalist category to almost 20 with products on the market; Vibram’s sales doubled every year between the company’s founding in 2006 until 2011.

The academic guru of barefoot running, Lieberman not only studies it extensively, he actually practices what he preaches. The human and evolutionary biologist thinks barefoot running is healthier than running in shoes, as makes the intrinsic foot muscles that support the arch work harder, strengthening the foot. Many runners started using minimalist shoes as a result, in the hopes of developing stronger foot muscles.

Lieberman says that typical shoes have features like thick soles and even thicker heel pads that let the foot do less work. He even goes so far as to imply that if shoes weaken intrinsic foot muscles, by enabling underuse, they thereby increase the chances of developing a low or collapsed arch.

But it turns out the jury’s still out on this particular debate.

A paper published in June’s Journal of the Royal Society Interface contradicts Lieberman’s findings. Luke Kelly and his team at the University of Queensland, Australian found that there was actually an increase in foot muscle use when people ran with shoes versus running barefoot, because the foot had to interact with the soft landing surface of the shoe and needs more muscles for stability. Sneaker-clad feet had to use more muscles than their barefoot counterparts—implying that using shoes doesn’t necessarily equate weaker foot muscles.

It’s unsurprising that Lieberman is skeptical of these results, given his research asserting the opposite.

While foot muscle strength has little to do with the injuries associated with barefoot running, this continuous academic discussion proves we don’t know everything. Both sides—barefoot opponents and proponents—need to be taken with a grain of salt.

Fun fact: If you head to Lieberman’s barefoot running website, you’ll see a little funding disclaimer at the bottom: “Research presented on this site was funded by Harvard University and, in part, by Vibram USA®.” Kelly’s paper, too, has a line at the end saying Asics Oceania Pty Ltd. funded the research. A quick Google search reveals this is an athletics shoe retailer in New South Wales, Australia.

Yikes. While neither of the researchers admitted any conflict of interest in their work, it is difficult to take their claims about the benefits of running in shoes versus barefoot at face value when vested interests are involved.

My story certainly didn’t fit Lieberman’s idyllic paleo-narrative, and I’ve now found I wasn’t the only one contending with injuries post-Vibram clad foolishness. Kevin Kirby, a podiatrist from Sacramento whom I spoke with last month, calls barefoot running nothing more than a “great economic stimulus plan for podiatrist and physical therapists.”

At the height of the fad from 2012-2013, Kirby saw an uptick in injuries like metatarsal stress fractures—people were breaking the foot bones closest to their toes. He says this made sense, given that barefoot runners tend to run toe-heel, absorbing ground force impacts with the midfoot rather than the heel. Minimalist shoes have no additional heel to absorb ground reaction forces generated when runners’ feet impact the ground, unlike more traditional sneakers.

It’s no secret that Vibram and other minimalist shoe companies co-opted the barefoot running trend to sell more product. But it’s ironic to observe that these companies may have crippled the trend at the same time (pardon the pun), by encouraging runners to run barefoot too much too fast, causing them to eventually abandon the endeavor due to injury.

These days, more of Kirby’s patients are running with thicker-soled shoes than ever before. Every third runner he sees wears Hokas, a sneaker brand with the thickest underfoot cushions in the market today.

He counseled me to buy a pair.

[This piece was first published on the Scientific American Guest Blog on January 5, 2017. Many thanks to SciAm editor Michael Lemonick for his assistance and support with publication.] 

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Aylin Woodward is a science writer and biological anthropologist in the 2017 UC Santa Cruz Science Communication program. She loves being outdoors and misses the granite of New Hampshire at times. She used to love running, but has since replaced it with various esoteric athletic activities… like roller derby.