Plank Knee Pull-In
1. Start in plank position, with your shoulders directly over your hands, your torso straight and your weight distributed evenly between your arms and legs.
2. Draw your left knee into your chest, flexing the foot while rocking your body forwards over your hands. You should come up on the toes of your right foot.
3. Extend your left knee backwards, rocking the body back, and shifting your weight onto your heel. With your head in between your hands, straighten your right leg and lift it towards the ceiling. Repeat.