Plank With Leg Raise

Place your hands shoulder-width apart on top of a stability ball that's resting against a wall. Extend your legs to balance on toes and hands, and tighten your abs so your body is aligned from head to heels [A].

Lift left foot a few inches off floor. Hold for up to 5 counts, lower it, and lift right foot. Repeat, alternating feet, until you've done 5 lifts per side [B]. Work up to 10, then try doing it with the ball moved away from the wall.

Strengthens:

core