Starting Position: Lie supine (on your back) on an exercise mat or the floor in a bent-knee position with your feet flat on the floor and your arms resting comfortably along your side with the palms rotated up to face the ceiling. Start with your feet hip-width apart with the toes facing away from you, lift the left leg and place both hands on the back of the thigh to gently pull your left knee towards your chest, slide the right foot in (towards the center of the body). Gently contract your abdominal muscles to flatten your low back into the floor. Attempt to maintain this abdominal stiffness throughout the exercise.
Upward Phase: Gently exhale while holding your abdominal contraction and the back of your left thigh; press your right foot into the ground and lift upwards off the floor into hip extension by contracting (squeezing) your right glute (butt muscle). At the same time press your right heel into the floor for more stability. Avoid pushing your hips too high as this generally increases the amount of hyperextension (arching) in your low back. Maintaining your abdominal contraction helps avoid excessive arching in your low back.
Lowering Phase: Inhale and slowly lower yourself back towards your starting position by controlling the action of the right hip. Repeat for a specific number of repetitions or a certain period of time; then alternate legs.
Exercise Variation: To increase the strength of the muscles along the front of the shin (anterior tibilias) pick the toes of the right foot off of the floor to hold the foot in dorsiflexion-this is a good option for runners because it could help reduce the risk of developing shin splints.