In the days and weeks before the 2020 Tokyo Summer Olympics, Biles was observed practicing — and nailing — a vault move known as the Yurchenko double pike. As The Washington Post reported, the move, named for Soviet gymnast Natalia Yurchenko, involves doing a round-off onto the springboard, followed by a back handspring onto the vault. From there, the gymnast launches into the air and does a flip — or in Biles’ case, two and a half flips.

Variations of this maneuver have been attempted in olympiads and other gymnastics competitions over the decades, but Biles is amping up the difficulty with two and a half rotations. “You need the speed of the run and the height to get those two and a half rotations. And it’s also dangerous if you don’t do it correctly,” said judge Emily Chan, via Yahoo! News. No female gymnast has ever performed it in competition, according to The Daily Mail.

If Biles lands it the wrong way, she could wind up with head or neck injuries that could prematurely end her career, if not her ability to walk. Further, according to Esquire, the move is so dangerous that judges, in an attempt to discourage it in competition, start with a lower base score for any gymnast attempting it. Fortunately, says the Post, she’s been nailing the move with such ease at her training sessions that no one has even batted an eye.