We thought we were seeing double when we came across this exercise performed by both Rosie Huntington-Whiteley and Stella Maxwell on Instagram. The blond bombshells demonstrated the bum-and-thigh-targeting combo, which begins in a plank atop a yoga ball (or, if you’re Rosie, an upside-down recycling bin). Once you’re set up, bend your left knee in toward your left elbow—all while keeping your core firm and back straight—and return to the starting position, crossing your foot over your standing leg to finish. Repeat for a few reps, then switch legs. We can’t promise that you’ll get a bod as bangin’ as these two overnight, but you can be sure that this is a move that will, in the words of Huntington-Whiteley, kick your “arse.”
—Karina Hoshikawa, Style.com
