This weekend, 50,000 runners will toe the line at the New York City Marathon (the world's largest 26.2!)—and we’re guessing that, throughout their training, many of them could relate to the narrator in the quick flick below: “I’m 15 miles into this run,” he says, groaning. “I have another seven to go. I’m losing steam, my legs are cramping, I can barely breathe. I don’t know if I can make it another mile!”

While we hope the marathoners feel better than that on Sunday morning, we’ll admit it: We’ve been there.

The video, from the American Chemical Society, goes on to explain the science behind why we “bonk,” “hit the wall,” or, if we’re lucky, catch the drug-like runner’s high. (Hint: It’s got a lot to do with proper training.)

If you’ve ever wondered why it’s important to carbo-load, what that burning feeling in your legs really means, why you sweat so much, and whether you can drink too much water, the answers are here.

RELATED: The 50 Most Gorgeous Running Races in America, State by State

Whether you’re racing this weekend or not, give it a watch. Then get out there and go chase that dopamine rush—through NYC’s five boroughs or wherever you love to pound the pavement. Good luck, marathoners!

 

Contrary to what many people may believe, it’s not war or landmines that are the primary causes of amputations in impoverished countries.

In places like Kenya or India, amputations are often the result of more commonplace and unfortunate incidents, like automobile accidents or train mishaps involving businesspeople on their commutes to work.

Each year, tens of thousands of people in low-income nations suffer amputations, explained Dr. Krista Donaldson, CEO of medical device non-profit D-Rev, at Fortune’s Brainstorm Health conference in San Diego Wednesday.

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Modern prosthetic limbs are often expensive, she said, with some devices costing upward of $1,000, making it hard for struggling medical clinics to afford them. And even when those devices are donated to clinics operating in impoverished nations, frequently those devices go unused, and the clinics are unable to perform the maintenance required to keep them functional.

“Most medical devices are designed for places like here, not low-income clinics,” Donaldson said in reference to clinics in wealthy nations that can more easily afford and maintain the prosthetics. D-Rev created more affordable prosthetic limbs to help amputees worldwide who don’t have access to the medical devices.

For instance, Donaldson showed off a recently developed artificial knee that costs $80 and contains the organization’s custom technology such as an embedded spring that helps amputees move the artificial leg forward as they walk.

The artificial knee was also designed to accommodate uneven terrain and rocky roads, unlike other devices built with smoother, paved surfaces in mind.

Currently, the knee is being used in 17 countries, but she hopes to bring it many more nations over the next three-to-five years.

For more from Brainstorm Health, click here.

This article originally appeared on Fortune.com.

Once, when I was in high school, I got to do the makeup for a car-accident demonstration thing that was surprisingly gory and fun. I watched some grainy how-to videos of special-effects makeup, and I was hooked.

Although I don't play around with makeup in that same way (zero fake blood in my everyday makeup routine, sigh) I still love watching special-FX makeup artists on YouTube transform themselves or others.

Any of these videos that need to move or drastically change the brows usually did so with some sort of brow cover-up that included a glue stick or spirit gum or wax, all of which sounded like really fun ways to lose half your eyebrow hairs when trying to take it all off. But I came across a few that used soap to replace glue, which would make clean-up a million times easier because your cleanser is right there on your face, waiting for you. But that trick didn't have any real-life application for me.

Then I saw one of my favorite makeup artists on YouTube use soap to style her brows for a normal makeup look. 

MIND. BLOWN.

So, obviously, I had to try it.

First, I tried it the special-FX makeup way. All you have to do is take a humble bar of soap, dampen it a bit so it's not dripping but wet enough to move, and apply it lightly to the brows.

Since the goal isn't to erase my brows completely, this really didn't work because it applied way too much soap and just gave a crazy white cast to my brows and felt really heavy and gross.

Don't do that.

Instead, take the eyebrow brush of your choice, wet it, and scrub it all up in that soap.

With enough suds on the brush, you can easily brush it through your brow hairs. I typically don't style my brows upwards like this, but it was really hard for you to see the effect any other way.

When you inevitably have soap all over your brows, lightly press with a tissue to remove the excess bubbles while keeping the soap stuck in your brow hairs.

From there, you can let your brows dry and apply any brow powder/pomade/pencil of your choosing, I would just stay away from brow-gel-type products so it doesn't get all gummed up with the soap.

So did this work? Yeah, totally. It took maybe a minute or two per brow, and my brows stayed up and perky for a good six hours or so. Honestly though, my usual brow routine of powder and maybe hairspray on a spoolie lasts longer than this.

It all comes down to the soap you choose. The Dove bar I've been using has a lot of moisturizing agents included to make your skin much happier. A better choice would be a harder, less moisturizing soap. The fats and oils that give real soap that almost waxy feeling would give significantly better results in holding your brow hairs in place.

Now my question is, can this same technique be used for taming baby hairs and flyaways? We shall see.

 

This article originally appeared on xoVain.com.