HOW: Start this exercise on your back in a 90/90 position. Keep the small of your back pushed into the floor by activating your core. While maintaining core activation drop one leg towards the floor. When lowering your legs, bring one leg down at a time while maintaining the right angle, then return to the starting position and repeat.
FEEL: You should feel the abdominal muscles engaging while you perform this exercise.
COMPENSATION: Do NOT let the low back arch with this exercise or straighten/bend your knee.