Anna Kaiser's known as one of the top trainers in the business—clients including Karlie Kloss, Alicia Keys, and Shakira turn to her for effective workouts, and she delivers. But you don't have to be a ...

The singer's tight core comes courtesy of the corkscrew obliques pulse, an exercise led by AKT in Motion founder Anna Kaiser. This crunch works both the obliques and the transverse abdominis (TVA)—the ...