To do Crescent, step one foot forward into a wide stance and bend the front knee to sink into a deep lunge while keeping the back leg out straight. Your front heel should stay down while your back heel will be up. Make sure you are really sitting back into your front heel as you are driving your back heel down toward the ground to straighten your back leg.
Hold in this low lunge and lift your hands up and back overhead. Keep your front heel down as you sit back into the lunge. If your front heel is coming up, you may want to step your front foot forward a bit more. Make sure your front knee isn’t caving in and is aligned over your ankle.
As you hold the lunge, feel a nice stretch down your back hip and quad. Really squeeze your glutes to press your back hip forward and to keep your front knee from caving in. Make sure that you are extending your hips and not arching your low back as you reach overhead.
Also, make sure your low back isn’t hyperextending as you reach back overhead. By squeezing your back glute, you will make sure your hip is stretching.