- [Narrator] Cheetahs are
the fastest land animal in the world. But did you know that humans
can leave them in the dust? At least in the long run. That's right, when it comes to endurance, we can outrun wolves,
cheetahs, and even horses. Now in the beginning, humans fall short, because we're lousy sprinters. Case in point, Usain Bolt
couldn't outrun a cheetah in the 100-meter dash if he wanted to. And he tried. But marathons and ultra-marathons are a whole other ball game. Each year, a small town in Wales holds the Man Versus Horse Marathon. It's a 22-mile race between
riders on horseback and runners. And while horses often win,
humans will sometimes prevail. So what makes humans such
endurance running superstars? The secret weapon is our sweat. We have two to four million sweat glands all over our body, which means we can run and cool
ourselves at the same time. Having no fur is also a huge plus. In contrast, dogs rely
on panting to cool down, and other animals, like horses and camels, also sweat, but less effectively. As a result, they overheat
faster and must slow down sooner. The mechanics of our running stride also makes us particularly well-suited for endurance running. A human's running gate
has two main phases. Aerial, when both feet are off the ground, and Stance, when at least
one foot touches the ground. While in the air, gravity pulls us down, which generates a lot of kinetic energy. However, the second we hit the ground, we instantly decelerate, losing that kinetic energy in the process. Some of it goes into vibrations and sound as we strike the ground, but most of it actually goes
straight to our tendons. Here's where our special
adaptations come in. The tendons and muscles in
our legs are very springy. They act like a pogo stick, converting kinetic energy
from the aerial phase into elastic potential energy,
which we can use later. In fact, our IT Band
can store 15 to 20 times more elastic energy than a
chimpanzee's similar body part, the fascia lata. When it comes time to step
off, those springy tendons can turn 50% of that
elastic pogo stick energy back into kinetic, making
it easier to propel forward. Without that extra energy, we'd have to exert that much more effort just to take a step. So how did humans get to be
such great endurance runners? Some anthropologists believe
this became important around two to three million years ago, when we started hunting and scavanging. Because we couldn't chase
down a gazelle like a cheetah, early humans learned persistence hunting, where they would track
prey over long distances until the prey either overheated,
or was driven into a trap. In fact, persistence hunting
remained in use until 2014, such as with the San people
of the Kalahari Desert. But distance running can still help you, even if you're not interested in running down your next meal. Studies show running
can lower body weight, body fat, and cholesterol levels. And the longer you train, the
greater the health benefits. Just one year of training has been shown to reduce body weight
by about seven pounds, lower body fat by 2.7%, and decrease resting heart rate by 2.7%. It may seem really hard, or maybe even impossible to
run a mile or a marathon. But in fact, you were
born to go on that run. We all were. (upbeat music)
