KEY AREAS: Core, Spine, Pelvis
START POSITION: Lie down in a supine position with your head on the floor (don’t lift it up). Raise both legs so that your knees are directly above your hips and your thighs are vertical from hip to knee. This resembles lying on the floor with your feet up on a tabletop (which is not actually there of course).
NOTES: Keep one leg where it is and bring the other one down until the heel touches the floor. Only move from the hip. Keep the knee rigid so that it has a constant 90° angle. Then reverse the movement back up to the start position. You can either alternate both legs with just one rep each or you can do several reps on each leg before switching legs. Just be sure to keep the movement smooth and not too fast. You are looking for your foot to tap the floor gently, and not use the foot to push the leg back up. Draw your belly button down towards your spine throughout the manoeuvre but relax it out briefly at the top position.
There are several different forms of this exercise, with various names. This form is the easiest to accomplish, but it can be made more difficult in several ways as you get fitter.