The Physics of Simone Biles

[calamity]

At 4'8", and all muscle, Simone is an absolute marvel of the human anatomy. And, it turns out, it's the perfect build for tumbling.

Check this out. It breaks it all down to the nuts and bolts of the matter. The video is absolutely worth the minute and half, or whatever it is, spent. I watched it a few times.

Rio Olympics 2016: Is anyone or anything better at gymnastics than Simone Biles? — Quartz

When Biles launches off the mat, she pushes down with her feet, sending her body upwards. It takes a lot more work for heavier gymnasts to manage the same jumps. Biles benefits from having—like most shorter athletes—a muscular build while still weighing relatively little. In other words, Biles has the ideal body type for this kind of trick.
After Biles picks up velocity, she needs to direct all that speed toward her backflip. She needs to take off at the exact right angle, and then she needs to do some blink-of-the-eye adjustments in midair. It comes down to this: throughout the trick, Biles is making herself consistently shorter. She starts with her arms above her head, before moving them downward and then arching her back. In doing so, she can increase her velocity, meaning she’ll somersault faster than if she kept her body outstretched. That gives her time to complete two full flips.