TOKYO (Nexstar) – Before Simone Biles withdrew from Thursday’s all-around gymnastics competition at the Tokyo Olympics, she competed at the vault. Things didn’t go exactly as planned.

Biles said she lost herself mid-air. She meant to do 2 1/2 twists, but only did 1 1/2.

Later, she told reporters, “They saw it a little bit in practice. Having a little bit of the twisties.”

What are the “twisties?”

Gymnasts explain it’s sort of like your mind and body disconnecting mid-air, so you’re not quite sure where you’re at mid-flip, making it hard to land safely.

“I’ve had the twisties since I was 11,” said fellow Olympic athlete Leah Finnegan on Twitter. “I cannot imagine the fear of having it happen to you during competition. … You have absolutely no control over your body and what it does. And the more you psych yourself out about [it], the worse it becomes.”

If you’re practicing back home, there might be a foam pit to catch you. In competition, the stakes are much higher.

Biles said in a press conference she was fine physically after her uncharacteristic vault this week. “That’s why I took a step back, because I didn’t want to do something silly out there and get injured.”