To appreciate the athleticism of gymnast Simone Biles, you have to watch her in slow motion. How she can propel her body high enough to clear a Ford Expedition while she unfurls with flips and…

KANSAS CITY, Mo. — When Simone Biles stepped up for the floor exercise Sunday night, she was prepared to attempt something the sport had never seen: a triple-double, meaning two flips and three twists. She…