American gymnast Simone Biles withdrew from several Olympic events [recently], including the latest withdrawal from the vault and uneven bars finals, after experiencing a case of “the twisties” — what gymnasts describe as losing control of their body mid-trick and losing sense of where they are in the air.
…
Through practice, athletes build and refine “very sophisticated” internal models of their movements [said biomedical engineering professor Kathleen Cullen.]
In other words, with training, athletes no longer need to think their way through the mechanics of every flip, throw or leap.
That said, when under pressure, athletes may try to take more conscious control of their motions, and this process can actually lead to errors, and sometimes the twisties.
“An athlete may try to compensate for increased physiological or cognitive stress or a lack of confidence by trying to consciously control movements that were previously automatic,” [sport psychologist Kelli] Moran-Miller said.