Prior to competing in the Olympics, Adam Ondra took a ballet class. "Climbing is a very complex sport," he said. "On the road to Tokyo, I need to widen my range of skills. ... Bouldering, lead ...

If you’ve ever held a plank, paused at the bottom of a squat or pressed your palms together in front of your chest, you’ve done an isometric exercise. Ta-da! These holds might look simple — after all, ...