I've never admitted this publicly, but when I was young, my mom enrolled me in gymnastics. I know, it may not be considered to be the manliest of sports by a young teen, and to be fair, she never made me wear tights.
But what intrigued me was how some of the skilled gymnasts my age, both male and female, were able to do incredible flips, twists and rotations, yet always managed to land on their feet. I was told that it takes a lot of practice, but they made it seem so easy! The same thoughts occurred to me again years later when watching the incredible acrobatics of a cheerleading squad at a university football game.
So with that, I've decided to look into the science of gymnastics and as it turns out, there are some pretty impressive physics going on behind the scenes.
Did you know? Most female gymnasts are at their best between the ages of 14 and 18.
Being able to execute an aerial feat has a lot to do with the gymnasts' centre of gravity. Gravity is a force; Forces pull objects in certain directions. Gravitational forces pull down and is what keeps us all on the ground. We often find ways to counteract those forces through other forces.
When gymnasts are in the air, it is important that they work with gravitational forces to perform their aerial maneuvers. Although gravity pulls them down, they must constantly orient their centre of gravity properly in order to pull off a move with success.
The centre of gravity is a balance point. Imagine standing up with your arms straight at your side. Your centre of gravity would be at your torso, because that's the centre of your balance. But stick your arms straight out in front of you and your centre of gravity shifts forward slightly.
Did you know? Typically a male's centre of gravity is higher than a female's.
In the same way, a gymnast's centre of gravity shifts depending on their body's orientation. If they are upside-down in a flip, their centre of gravity would be different than if they were rolling while tucked in a ball. The centre of gravity is constantly changing. If the gymnast doesn't keep it in control, the maneuver would flop.
Gymnasts can use their centre of gravity to their advantage, particularly in turns. When their arms or legs are extended, the radius of the amount of space the body is taking up increases, causing their centre of gravity to shift out and slow movement. The opposite is true too — the less space the body takes up, the closer the centre of gravity is to the body and the faster the speed of the movements.
The principle is easy to see as a gymnast can make more rotations when curled into a ball, than when their body is straightened out. This is also true for figure skaters — the closer their arms are to their bodies, the faster they spin.
So how do gymnasts know which way is up when they are in the middle of a flip? We use a few methods to help us keep our balance and sense of orientation. Our brains use something called the vestibular postural reflex to orient us, which helps us land on our feet — a reflex that is also very advanced in cats.
Did you know? There are springs under the floor mat gymnasts do their floor exercises on.
Our eyes are also a big component of keeping ourselves oriented. Another mechanism we use is the vestibular ocular reflex which helps us fix an object in place. Imagine turning your head when looking at an object and thinking its location has changed — it's the vestibular ocular reflex prevents that from happening.
All these factors help gymnasts perform amazing acrobatic feats. But like any other sport, it doesn't come naturally. All gymnastic skills, whether it be on the floor, horizontal bars or vault, have to be developed through practice and error. So unlike cats, there's no guarantee that a falling gymnast will land on their feet.
Stability and Balance of Gymnastics
Vestibular ocular reflex
Arlen is a native of Toronto with a joint BA from the University of Waterloo (UW). He is currently doing a MA in Journalism at the University of Western Ontario. A couple summers ago, he did research at Oxford in England for a professor from UW. He also competes in lifeguard competitions.