Simone Biles showed an example of courage as she announced her decision to retire from the Olympics to protect her body and mind. She told reporters she was experiencing some "twisties". But what is this dangerous phenomenon described by gymnasts?

"Twisties" is an informal term that refers to a mental blockage that a gymnast may experience during movements in the air. When one experiences "twisties," there is a disconnect between the brain and the body, Jamie Shapiro, a certified mental performance trainer, told Health. "The body knows what to do and motor programs are stored in the brain, but the brain has trouble accessing those motor programs," she explained.

Disconnecting the brain from the body can cause gymnasts to lose the ability to understand where they are in the air and to feel "a loss of control over movement." This condition can cause physical problems - as gymnasts can only understand where they are when they hit the ground - and mental - as it is associated with anxiety and mental blockage.

The reasons for this phenomenon can be complex and research in this regard is still ongoing. Some of the possible causes may be anxiety, stress, fear of failure, desire not to disappoint others and the pressure of high expectations.

In addition to these, it can also occur from focal dystonia, a neurological condition involving involuntary muscle spasms, which can result from overuse of muscle.