1. Lie prone on your palms and toes (as for push-up). Body is parallel to the floor. Hands are perpendicular to the floor: the shoulder, elbow joints and wrists are placed directly under each other. Squeeze your abs. Don’t arch your back, but slightly round it, if possible. Make sure, your abs is contracted throughout the exercise. This is your starting position.
  2. Exhaling, pull your knee towards the chest.
  3. Inhaling, return to starting position.
  4. Alternate your legs.

Tip: Perform in quick manner not less than 30 seconds.