Do three sets of 10 reps on each side as part of your ab or core program, or postworkout as a solid finisher.
Lie faceup and hold a set of light dumbbells with your arms extended straight up over your chest. Bend your knees and place your feet flat on the floor. Lift your heels to rise onto your toes, then press your hips up into a bridge. Extend one leg straight up toward the sky.
Simultaneously lower your leg toward the floor while low- ering the opposite arm/dumbbell down toward your head until they are parallel to the ground. Lift your arm and leg back to the start and continue, completing all reps on one side before switching.
Beginner tip: Keep your foot flat and/or eliminate the dumbbells.