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Why Walking Makes Us Feel Good

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Need a reason to get up from your desk? Scientists say each step we take sends a boost of blood to our brains, making us feel sharper and better overall. The research will be presented today at the Experimental Biology 2017 meeting in Chicago.

It’s no secret that exercise makes us happy. It raises our heart rates and floods our bodies with feel-good hormones. But until quite recently, scientists had not considered its effect on the flow of blood to the brain, or how that flow might affect our state of mind.

Researchers at New Mexico Highlands University (NMHU) began by studying the hemodynamic (blood-moving) effects of pedaling a bike, then looked at running. They found that both activities increased cerebral blood flow, as the impact of each footstep on the ground or pedals squeezed athletes’ arteries, sending a pulse of blood to the brain. The effect was especially pronounced in runners, whose feet hit the ground hard.

The scientists wondered if the same might be true of walking, with its relatively gentle footfalls. They hooked 12 healthy young volunteers up to heart monitors and ultrasound machines, then set them walking on a treadmill.

Sure enough, even a casual stroll boosted blood flow to the volunteers’ brains. The effect was significant, somewhere between the low-impact ride of cycling and running’s hard steps.

"What is surprising is that it took so long for us to finally measure these obvious hydraulic effects on cerebral blood flow," first author Ernest Greene said in a statement. "There is an optimizing rhythm between brain blood flow and ambulating. Stride rates and their foot impacts are within the range of our normal heart rates (about 120/minute) when we are briskly moving along."

The authors believe these boosts of blood—and therefore oxygen—to the brain may help clear our heads and lead to an “overall sense of wellbeing during exercise.”

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Big Questions
How Long Could a Person Survive With an Unlimited Supply of Water, But No Food at All?
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How long could a person survive if he had unlimited supply of water, but no food at all?

Richard Lee Fulgham:

I happen to know the answer because I have studied starvation, its course, and its utility in committing a painless suicide. (No, I’m not suicidal.)

A healthy human being can live approximately 45 to 65 days without food of any kind, so long as he or she keeps hydrated.

You could survive without any severe symptoms [for] about 30 to 35 days, but after that you would probably experience skin rashes, diarrhea, and of course substantial weight loss.

The body—as you must know—begins eating itself, beginning with adipose tissue (i.e. fat) and next the muscle tissue.

Google Mahatma Gandhi, who starved himself almost to death during 14 voluntary hunger strikes to bring attention to India’s independence movement.

Strangely, there is much evidence that starvation is a painless way to die. In fact, you experience a wonderful euphoria when the body realizes it is about to die. Whether this is a divine gift or merely secretions of the brain is not known.

Of course, the picture is not so pretty for all reports. Some victims of starvation have experienced extreme irritability, unbearably itchy skin rashes, unceasing diarrhea, painful swallowing, and edema.

In most cases, death comes when the organs begin to shut down after six to nine weeks. Usually the heart simply stops.

(Here is a detailed medical report of the longest known fast: 382 days.)

This post originally appeared on Quora. Click here to view.

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Medicine
Why Haven't We Cured Cancer Yet?
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Walkathons, fundraisers, and ribbon-shaped bumper stickers raise research dollars and boost spirits, but cancer—the dreaded disease that affects more than 14 million people and their families at any given time—still remains bereft of a cure.

Why? For starters, cancer isn't just one disease—it's more than 100 of them, with different causes. This makes it impossible to treat each one using a one-size-fits-all method. Secondly, scientists use lab-grown cell lines cultivated from human tumors to develop cancer therapies. Living masses are far more complex, so potential treatments that show promise in lab experiments often don't work on cancer patients. As for the tumors themselves, they're prone to tiny genetic mutations, so just one growth might contain multiple types of cancer cells, and even unique sub-clones of tumors. These distinct entities might not respond the same way, or at all, to the same drug.

These are just a few of the challenges that cancer researchers face—but the good news is that they're working to beat all of them, as this TED-Ed video explains below.

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