# Handstands, explained

It’s simple physics.

The 4-inch-wide balance beam, called "the most unforgiving surface in sports," may be the most mind-boggling of the four events in women’s gymnastics. It tests even the phenomenal Simone Biles, the five-time Rio Olympics medalist who wobbled and grabbed the beam to keep from falling — but still managed to medal in the event last summer.

Our brains can handle some balance without much effort: We take thousands of steps a day, and for split seconds between each stride we are balancing on one foot. That’s easy because our legs are strong and our feet have enough relative surface area to hold our weight.

But swap your hands or your toes for your feet, and it gets hard. For years, I have tried to teach myself to stand on my hands for long periods of time (more than 10 seconds, let’s say). I have managed to do it, but not consistently. And too often, I use the wall as a crutch — to catch me when I kick up too hard and start to fall backward.

Perfecting the art of the handstand has deepened my appreciation of gymnasts like Olympian Gabby Douglas, above, who perform exquisite feats of hand balancing on the beam.

But I’ve also learned how to think about my body in a new way and appreciate its center of mass. So let's dive into the physics, in honor of International Handstand Day.

### Get to know your center of mass

An object's center of mass is the "average weighted position of all of the tiny masses that comprise the object," according to the American Physical Society’s website Physics Central.

We humans have a center of mass that’s generally right above our bellybuttons. And the key to the handstand is to make sure your center of mass always remains right over your hands. So rather than worry about where your feet are once you’re perpendicular to the ground, you focus on your core.

The best thing I’ve ever seen that helps explain how this works is this GIF, annotated by Jonathan Matthis, a postdoctoral researcher at the University of Texas Austin who studies visual control in locomotion.

Matthis tells me that he saw the original version on the Instagram feed of the handstander himself, Las Vegas–based Aussie breakdancer and athlete Simon Sterara.

Matthis realized Sterara’s video was a perfect case study of the biomechanics of balance. "A person is a very complicated object," Matthis tells me. "But you can condense it down to that point: the center of mass. You can use it to approximate the mechanics of physics of a complex body."

What Sterara manages to do in this incredible handstand is move in a perfect vertical line, without arching his back. "All of his movements are balanced, so the center of mass movement only goes straight up and down," says Matthis.

The other secret to handstands is subtle actions of hands and fingers, which can help you steer your center of mass. If you look closely, you can see Sterara pushing into the ground as he descends. "The only place force can come from is in your hands," says Matthis. "You can only push on the ground to push the center of mass toward one line or the other."

Here’s more specific advice from Physics Central on how to use force to control center of mass: "If you start to fall forward, press hard into your fingertips, and your body will oscillate back toward an upright position. Inversely, if you start falling backward, you need to push into the base of your hand at the palm."

In addition to grappling with force and mass, you’re going to need core strength, arm and shoulder strength, and open shoulders to nail the handstand. (These step-by-step instructions from Yoga Journal and Progressive Calisthenics are helpful.) You may have to practice everyday. But the beauty of this process is that you can teach your brain to become more comfortable with defying gravity.

Scientists actually still have much to learn how the brain controls balance and movement. As Thomas Jessell of the Mortimer B. Zuckerman Mind Brain Behavior Institute at Columbia University told the Washington Post, the nervous system of an athlete like Simone Biles might have "innately good ‘wiring.’" But neuroscientists like him still haven’t ever located such special wiring in the brain. So science may one day school us further in the pursuit of the perfect handstand.