Often times we tend to extend through the lumbar spine instead of from the hips. Learning to disassociate one from the other can help improve lower back health. Here are a couple of exercises to work on. 1) Flexing the opposing hip during a Single Leg Glute Bridge will help you reach full hip extension on the working leg. 2) When performing a Bird/Dog exercise make sure to flex the lumbar spine to focus on extending through the hip instead of the spine.