The Leg Pull exercises are tough ones for me. They look easy on the outside but they require your entire body to resist gravity, resist sitting in your joints, and if anything you can simply hold the start position and think about the whole exercise. Picture each rep and maintain your connection until you are ready to lift the legs and move. This exercise is also great for preparing for Long Stretch on the Reformer. But, it also is excellent when you channel the Long Stretch as you do this exercise. If you can feel your legs really move your body you are going to find the strength you need.
Stay long, maintain your connections as you reach back and forth
Find your plank on the mat; shoulders over your wrist, hips up and reaching long, feet pressing down into the mat and fingertips pressing down into the mat. If you are like me, double-check your elbows and knees are not locked or hyperextended. If they are, you will tend to feel pressure in your wrists, shoulders, and even knees. Before you begin to do the leg lifts reach long out of your head and out through your heels. It's important to feel the opposition to maintain a connection to your center as you lift and lower your legs.
From your start position, lift one leg up and then reach it long behind you as you rock back and then forth. Set the leg down and then switch legs. Repeat 3 times on each side. As you reach back it will be easy to lift your hips. Keep them in line with your body and reach back through your heel. Then as you rock forward, instead of rounding your shoulders or allowing your hips to sink low, use your leg to help reach forward over your arms like you would in Long Stretch series on the Reformer. After you have completed both sides evenly transition from Leg Pull to Leg Pull Front.