Simone Biles: What are the twisties in gymnastics?

US gymnast Simone Biles, who pulled out of two Olympic finals on Tuesday citing her mental health, told journalists earlier that day that she was “having a little bit of the twisties”.

It’s a term that sparked immediate discussion among gymnasts who recognised right away how dangerous a situation this must have been. But for the rest of the world, it’s an unfamiliar term.