EXERCISE · BODYWEIGHT
Bicycle Crunch
Core
The one thing that decides whether this works is patience — sprint through it and you're just windmilling your legs, slow it down and your obliques have to do real work to rotate your torso. Lie on your back, hands lightly behind your head, and bring one knee in while rotating your opposite elbow toward it, extending the other leg straight and low. Switch sides in a smooth, unhurried rhythm rather than racing through reps. Keep your lower back pressed into the floor throughout — if it arches up, you've dropped your legs too low or sped up too much.