The resisted single-leg stretch is a Pilates-inspired exercise that increases strength and stability throughout the core including the lower abdominals.
Lie on your back with both knees brought toward your chest.
Extend one leg straight in front of you as you press your hands into your other thigh. Lift your head and shoulders off the floor as if performing a crunch. Drive your knee toward your chest as you continue to press into it with your hands. Hold, then return to starting position.
Hold your leg out extended and try to stabilize your body and avoid movement.
Don't round your back.
Extend your leg as far as possible and maintain tension on your abs.