A lot of gymnastics has to do with the center of gravity.
The shorter a gymnast is, often the easier it is to get the rotation he or she needs, no matter the event.
"Layout is the hardest to rotate. Your body is the longest at that point, so you have the longest radius from the center of your mass to the tip of your toes," said Kristin Alexy, Gymnastics Director for South Bay Family YMCA.
Gold medalist Gabrielle Douglas, for instance, measures at a slight 4'11'' and 90 lbs.
“If you're in a ball, the radius isn't nearly as long and your body can flip a lot faster."
On bars, for example, when gymnasts' bodies are completely stretched out, and they go all the way around the bar, which is called a "giant," it's all about "tapping" their toes.
And, doing it at just the right time. Alexy said if gymnasts' hips don't come right over the bar, along with their toes, they'll be in trouble.
"When you're under the bar, or right almost coming underneath the bar, your toes should almost slightly behind you,” Alexy said. “Rright when you're passing through the bottom part of the bar is when you want to scoop our toes, tap your toes up, to complete the giant swing. If you tap too early or too late, you might not make it over the top.”
Due to changes in age requirements, Alexy said we're now seeing older gymnasts in the Games.
If gymnasts go through growth spurts, their center of gravity changes, which often means they have to develop more core strength, to pull those legs over, or to get the rotation they need.