Superstar gymnast Simone Biles defended her decision to withdraw from Olympic competitions on her Instagram story on Thursday night, explaining that she is still struggling from what is known as the “twisties,” and isn’t sure if she will be able to compete in individual competitions scheduled for next week.

This week, Biles pulled out of both the team final and the women’s individual all-around at the Tokyo Games to focus on her mental health. Team USA won silver in the team event, and Biles’ teammate Suni Lee won gold in the individual — the fifth American woman in a row to do so.

Opening up on Instagram stories overnight, Biles, a six-time Olympic medalist, answered questions from her fans about a condition that gymnasts call the “twisties” — a frightening state of disassociation that prevents athletes from successfully completing a skill, which can lead to serious injury.

“I can’t even fathom twisting. I seriously cannot comprehend how to twist,” Biles wrote on Instagram, attempting to explain how the twisties feel. “Strangest and weirdest thing as well as feeling.”

Biles said that, while training this week, she has not been landing the moves she is meant to perform in competition. She said that she has been affected in every apparatus, “which sucks…really bad.”

Biles added that she has experienced the twisties before and “they’re not fun to deal with.” She said they started happening after the preliminary round earlier this week.

“It’s honestly petrifying trying to do a skill but not having your mind and body in sync,” she explained. “10/10 do not recommend.”

“Literally can not tell up from down. It’s the craziest feeling ever. Not having an inch of control over your body,” she continued. “What’s even scarier is since I have no idea where I am in the air I also have NO idea how I am going to land. Or what I am going to land on. Head/hands/feet back…”

Biles also continued to defend her decision to remove herself from competition for her own safety.

“I didn’t have a bad performance and quit. I’ve had plenty of bad performances throughout my career and finished competition,” she said. “I simply got so lost my safety was at risk as well as a team medal.”

“I don’t think you realize how dangerous this is on hard/competition surfaces,” she added. “Nor do I have to explain why I put my health first. Physical health is mental health.”

Biles qualified in all six of the women’s gymnastic finals — team, individual all-around, vault, uneven bars, balance beam and floor. It’s not clear if she will compete next week.

“Typically for me, it’s usually two or more weeks when I’ve had them before,” she said of the timeline. “Honestly no telling/time frame, something you have to take literally day by day, turn by turn.”

USA Gymnastics said on Wednesday that Biles will be evaluated daily to determine if it is safe for her to participate in next week’s finals.