In their latest article about improving your core and achieving a flatter tummy and stronger abs through pilates, they contacted our own Heather Jeffcoat, DPT for her expert opinion:
This is a great exercise to build endurance of your deepest abdominal muscle, the transverse abdominus," said Heather Jeffcoat, DPT, a physical therapist and BASI-certified Pilates instructor at Fusion Wellness & Physical Therapy. This muscle supports your posture, she explained, and is "the primary muscle that flattens your lower abs and narrows your waist.
Lie on your back with your feet flat on the floor. Contract your pelvic muscles and deep lower abdominal muscle towards your spine.
Lift one leg at a time, bringing your hips and knees to 90 degrees. Make sure your pelvis is in neutral position with a slight curve in your lower back (not pressed flat to the floor).
Hold for as long as you can, building up to two minutes.
To advance the exercise, lower one foot down to the floor with control, using your core muscles. Touch your toes to the floor and inhale as you lift back up. Repeat on the other side for one rep.