Cushioned shoes aren't good for your feet

More and more research points to a serious mistake we made in how biomechanics works.

Cushioned shoes aren't good for your feet
Photo: Spencer Platt/Getty Images
  • A new study from Helsinki found that the more you cushion your feet, the more likely you'll get injured.
  • This follows previous studies showing that cushioned shoes leave you more susceptible to pain and injury.
  • A few million years of evolutionary design has been usurped by shoe marketing campaigns.

A lot happened to our feet in the transition from being quadrupeds to exclusively bipedal. While the upright organization of our limbs and organs resulted in many benefits in our communication skills and ability to breathe, for example, it greatly decreased the strength and flexibility of our feet, which once needed bendable toes that could grasp tree branches and a healthy dose of keratin, the protein that forms calluses, which protected us from sharp objects on the ground.

For most of the millions of years we've been evolving we didn't wear shoes; during the 45,000 years we've been wearing some form of footwear they've been minimal. More aesthetically complex (and biomechanically questionable) fashion-forward shoes and sandals are a few thousand years old, though finding a society that championed elaborate footwear took time. The decision to confine our feet in tighter spaces higher up off the ground was one of status, not anatomy—only"savages" didn't properly protect and adorn their feet.

It's been a decade since the (slightly) controversial Born to Run was published, and so it's been a decade that the minimalist versus cushioned shoe debate has been raging. (The argument for both has existed far longer, but that book brought it to the forefront of the growing running community's consciousness.) When Vibram was sued for making false health claims, cushioned shoes advocates rejoiced, even if the lawsuit focused on to inflated claims, not the utility of going "barefoot."

Besides, citizens of economically-advanced societies are not going to go full barefoot. While our feet would likely grow calluses as they (painfully) became accustomed to hard surfaces, what really matters to runners is impact peak. When walking, this force is equal to your body's weight, but when running that forces triples in weight. Despite constant debate about best running form, some people naturally heel strike, which is easier on your calf muscles and Achilles tendon and allows you to lengthen your stride more easily. When walking, we mostly heel strike first.

But as Christopher McDougall wrote in Born to Run, running is more like jumping than walking. Right now if you jump while barefoot, you're going to land on your forefeet. Cushioned shoes won't allow you to forefoot strike naturally; they also cushion the impact peak so that you don't feel the weight of each strike. While running shoe companies have marketed this as a bonus, Daniel Lieberman points out the downsides:

Runners who generate higher, more rapid impact peaks are significantly more likely to accumulate repetitive stress injuries in their feet, shins, knees, and lower back.

Research he conducted on the Harvard cross country team discovered that heel strikers were twice as likely to be injured than forefoot strikers. Minimalist footwear decreases the likelihood you'll heel strike, thus decreasing the risk of injury.

Now a new study published in Scientific Reports backs this up—sort of. The Helsinki-based team points out that while seemingly advanced technologies in cushioned shoes keep appearing, rates of injuries do not. Their study notes what Lieberman discovered years ago: the more you pad your feet, the more intense the impact peak, thus the higher the injury rate:

We found that highly cushioned maximalist shoes alter spring-like running mechanics and amplify rather than attenuate impact loading… We attribute the greater impact loading with the maximalist shoes to stiffer leg during landing compared to that of running with the conventional shoes. These discoveries may explain why shoes with more cushioning do not protect against impact-related running injuries.

This small study of twelve men (average age: 27) compared conventional-cushioned shoes with maximally-cushioned shoes, so it's impossible to use it in making an argument for minimalism. That said, if you consider that impact peak will be reduced with less cushioning, we can extrapolate to confirm what Lieberman (and others) have advocated: the more you swaddle your feet in what biomechanist Katy Bowman calls "foot coffins," the more likely you're going to injure yourself.

Feet are amazingly complex structures. We often forget that—until they hurt, which happens more often in modern societies. Each foot has 26 bones and 33 joints that connect over 100 muscles, ligaments, and tendons. Everything we do depends on the health of our feet, yet every day most people slide them into small, padded spaces with little room for movement, and we haven't even touched the ankle joint yet. But Bowman does:

The ideal footwear is "none" for any human. A shoe will weaken the function of the musculature within the foot (intrinsic) by limiting the motion to the ankle.

Arch support atrophies the muscles up the chain dependent on strong arches; lack of ankle flexility has system-wide effects. Instead of strengthening those muscles, most responses to problems like plantar fasciitis—a condition I see often in my role as fitness instructor—are to continually baby the feet. Fascia needs lubrication to work effectively. Further padding the feet in an attempt to reduce inflammation is the exact opposite path to successful healing, but by the time you've acquired this particular ailment, the harder it's going to be to move without pain, creating a tragic feedback loop that severely restricts movement.

What seems like progress is often regressive, especially when we choose aesthetics over form. Squatting, for example, is the means by which our bodies were designed to defecate. Toilets were a societal advancement that was (and still is in many countries) indicative of class, yet the ninety-degree angle of that seated arrangement does more harm than good to our ability to "go."

So it is with cushioned shoes. Given the bacterial playground that is the ground, going completely barefoot is not in our best interests. But common sense is. Millions of years of evolving design do not surrender their anatomical wisdom without severe consequences.

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A landslide is imminent and so is its tsunami

An open letter predicts that a massive wall of rock is about to plunge into Barry Arm Fjord in Alaska.

Image source: Christian Zimmerman/USGS/Big Think
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  • A remote area visited by tourists and cruises, and home to fishing villages, is about to be visited by a devastating tsunami.
  • A wall of rock exposed by a receding glacier is about crash into the waters below.
  • Glaciers hold such areas together — and when they're gone, bad stuff can be left behind.

The Barry Glacier gives its name to Alaska's Barry Arm Fjord, and a new open letter forecasts trouble ahead.

Thanks to global warming, the glacier has been retreating, so far removing two-thirds of its support for a steep mile-long slope, or scarp, containing perhaps 500 million cubic meters of material. (Think the Hoover Dam times several hundred.) The slope has been moving slowly since 1957, but scientists say it's become an avalanche waiting to happen, maybe within the next year, and likely within 20. When it does come crashing down into the fjord, it could set in motion a frightening tsunami overwhelming the fjord's normally peaceful waters .

"It could happen anytime, but the risk just goes way up as this glacier recedes," says hydrologist Anna Liljedahl of Woods Hole, one of the signatories to the letter.

The Barry Arm Fjord

Camping on the fjord's Black Sand Beach

Image source: Matt Zimmerman

The Barry Arm Fjord is a stretch of water between the Harriman Fjord and the Port Wills Fjord, located at the northwest corner of the well-known Prince William Sound. It's a beautiful area, home to a few hundred people supporting the local fishing industry, and it's also a popular destination for tourists — its Black Sand Beach is one of Alaska's most scenic — and cruise ships.

Not Alaska’s first watery rodeo, but likely the biggest

Image source: whrc.org

There have been at least two similar events in the state's recent history, though not on such a massive scale. On July 9, 1958, an earthquake nearby caused 40 million cubic yards of rock to suddenly slide 2,000 feet down into Lituya Bay, producing a tsunami whose peak waves reportedly reached 1,720 feet in height. By the time the wall of water reached the mouth of the bay, it was still 75 feet high. At Taan Fjord in 2015, a landslide caused a tsunami that crested at 600 feet. Both of these events thankfully occurred in sparsely populated areas, so few fatalities occurred.

The Barry Arm event will be larger than either of these by far.

"This is an enormous slope — the mass that could fail weighs over a billion tonnes," said geologist Dave Petley, speaking to Earther. "The internal structure of that rock mass, which will determine whether it collapses, is very complex. At the moment we don't know enough about it to be able to forecast its future behavior."

Outside of Alaska, on the west coast of Greenland, a landslide-produced tsunami towered 300 feet high, obliterating a fishing village in its path.

What the letter predicts for Barry Arm Fjord

Moving slowly at first...

Image source: whrc.org

"The effects would be especially severe near where the landslide enters the water at the head of Barry Arm. Additionally, areas of shallow water, or low-lying land near the shore, would be in danger even further from the source. A minor failure may not produce significant impacts beyond the inner parts of the fiord, while a complete failure could be destructive throughout Barry Arm, Harriman Fiord, and parts of Port Wells. Our initial results show complex impacts further from the landslide than Barry Arm, with over 30 foot waves in some distant bays, including Whittier."

The discovery of the impeding landslide began with an observation by the sister of geologist Hig Higman of Ground Truth, an organization in Seldovia, Alaska. Artist Valisa Higman was vacationing in the area and sent her brother some photos of worrying fractures she noticed in the slope, taken while she was on a boat cruising the fjord.

Higman confirmed his sister's hunch via available satellite imagery and, digging deeper, found that between 2009 and 2015 the slope had moved 600 feet downhill, leaving a prominent scar.

Ohio State's Chunli Dai unearthed a connection between the movement and the receding of the Barry Glacier. Comparison of the Barry Arm slope with other similar areas, combined with computer modeling of the possible resulting tsunamis, led to the publication of the group's letter.

While the full group of signatories from 14 organizations and institutions has only been working on the situation for a month, the implications were immediately clear. The signers include experts from Ohio State University, the University of Southern California, and the Anchorage and Fairbanks campuses of the University of Alaska.

Once informed of the open letter's contents, the Alaska's Department of Natural Resources immediately released a warning that "an increasingly likely landslide could generate a wave with devastating effects on fishermen and recreationalists."

How do you prepare for something like this?

Image source: whrc.org

The obvious question is what can be done to prepare for the landslide and tsunami? For one thing, there's more to understand about the upcoming event, and the researchers lay out their plan in the letter:

"To inform and refine hazard mitigation efforts, we would like to pursue several lines of investigation: Detect changes in the slope that might forewarn of a landslide, better understand what could trigger a landslide, and refine tsunami model projections. By mapping the landslide and nearby terrain, both above and below sea level, we can more accurately determine the basic physical dimensions of the landslide. This can be paired with GPS and seismic measurements made over time to see how the slope responds to changes in the glacier and to events like rainstorms and earthquakes. Field and satellite data can support near-real time hazard monitoring, while computer models of landslide and tsunami scenarios can help identify specific places that are most at risk."

In the letter, the authors reached out to those living in and visiting the area, asking, "What specific questions are most important to you?" and "What could be done to reduce the danger to people who want to visit or work in Barry Arm?" They also invited locals to let them know about any changes, including even small rock-falls and landslides.

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