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As a SciShow viewer, you can keep  building your STEM skills with a 30 day free trial and 20% off an annual premium  subscription at Brilliant.org/SciShow. When it comes to shoes, there’s a lot that  goes into picking just the right pair.

A fuzzy pair of slippers can  keep you warm in the winter, or your favorite flip-flops might  just complete your beach-side look. But have you ever wondered what a lifetime of shoe wearing has done to your feet? To answer that question, scientists  are seeing what they can learn from the non-shoe wearers throughout the world, and what they’re finding might make  you see your footwear in a new light. [♪ INTRO] One of the most famously  barefoot groups in the world are the Kalenjin people of Kenya.

If you’re a runner, you may  have heard of Kalenjin athletes, because they have dominated  international races recently. Which might have something to do with  what it’s like to grow up as a Kalenjin, since Kalenjin children are incredibly active. These kids spend plenty of time playing outside, and some run as far as 20  kilometers to and from school, and usually, they’re doing all of that barefoot.

And it’s working pretty well for them,  since kids who spend most of their time barefoot end up building stronger, more flexible, and more robust foot muscles  than kids who wear shoes do. Those buff foot muscles offer more benefits, too. Barefoot kids are almost  eight times less likely to end up with lower limb  injuries than shoe-wearers are.

Not only that, but going  barefoot as a child may even play a role in the shape of your feet, too. When you see a human footprint, it  typically looks something like this: See that roundish gap there? That’s the space left by your longitudinal arch, or the natural bend upwards in the foot.

This arch helps us absorb shock and  spring ourselves forward while running. But some people’s footprints  don’t really look like that. Some of them look more like this,  which means they’ve got flat feet.

See, some peoples’ arches can  flatten under their own body weight, which can lead to other problems later on. And what’s interesting here is that  all babies are born with flat feet. Those arches only start to develop as  those toddlers start to, you know, toddle.

However, if they don’t develop  arches during childhood, those flat-footed kids can have trouble  walking or even have joint pain, which is why pediatricians might take  special notice of a kiddo’s foot development. In the early 90’s, some orthopedists in  India noticed that they weren’t seeing nearly as many flat-footed  children in their clinics as was reported out of  European or American clinics. And none of them could recall a  single flat-footed patient coming from the rural communities; it was just the  city kids who ended up with flat feet.

So, these doctors decided to conduct  a study to figure out what was so different about these two groups of kids’ feet. As it turns out, it comes down to shoes. See, the rural kids were much less  likely to wear shoes on a daily basis, and especially while playing,  than the city slickers were.

And that made a big difference,  since those barefoot kids were three times less likely to get flat feet. It turns out that the type of  footwear they chose mattered, too. Children who wore sandals were less likely to have fallen arches than those  who wore closed-toed shoes.

Most importantly, the team was able  to pinpoint that the critical age for arch development in children  is before six years old. But I’m willing to bet the majority  of our viewers are over that age. So if walking and running au naturel  is better for our feet as children, would it even matter if we  ditch our Nikes as adults?

Well, the answer isn’t super clear cut. There’s a contingent of athletes  who say that barefoot is best, especially for long-distance running. Proponents claim it helps to reduce the  impact of your foot hitting the ground, thereby decreasing the chance of injury.

See, it’s about how you stick the landing. Modern running shoes have  elevated and cushioned heels, which encourages you to land heel-first. On the other hand—or foot—running  without shoes has been found to encourage landing on the ball of your  foot, which generates less impact up the leg and lets your ankle  function as a kind of spring.

And a 2021 study found that daily activity  in minimal footwear as an adult can result in a roughly 50% increase  in foot strength over six months, which can lead to better  balance and a healthier gait. However, that’s not to say that  barefoot running is totally risk-free. It can put your feet in danger  of short-term stress injuries, which are influenced by factors like  body mass and running technique.

One of the most well-documented  risks deals with foot edema, or excess fluid trapped within the tissues.. Basically, when you increase  the stress on your feet, they can end up swelling up a whole bunch. And a hasty transition to running  without that cushioned heel we discussed earlier can be an effective way to  shock your body into that response.

Apart from just making your feet puff up, edema can cause a lot of  pain and make running harder. So the jury’s still out about whether  it’s best for an adult’s running form to kick their shoes to the curb. But for us slower-moving folks, shoes are probably still an okay  choice for our day-to-day lives.

And, to be perfectly honest,  most of us are probably not giving up our fuzzy slippers anytime soon! Thanks for watching this SciShow video,  and thanks to Brilliant for supporting it! Now that you know about  pressures that cause flat feet, you can learn what it really means  for your feet to be under pressure, by checking out the Physics  Puzzles Brilliant course.

The second lesson is literally  called “Under Pressure.” But when you learn with Brilliant,  you won’t just feel under pressure to cram a bunch of random information into your head. Instead, they make physics fun with 74 puzzles that teach you principles from  astrophysics to special relativity. And once you finish those puzzles, you can move on to chemistry puzzles,  or electricity puzzles.

There are a ton of new puzzles that were  just added to the Brilliant course catalog, so learning doesn’t get stale. You can find them all at Brilliant.org/SciShow  or click the link in the description down below to get started  with a free 30 day trial and 20% off an annual premium Brilliant subscription. [♪ OUTRO]