For many of us, when we think about working our core, we only think of doing abdominal exercises like sit ups and crunches.  We forget (or don’t realize) that our back is part of our core as well.  It is important to make sure we don’t create muscle imbalances by only working the anterior (front) side of our core.  Doing so can increase the chance of injury.  The Superman is a great exercise for strengthening many of the posterior core muscles such as the erector spinae, the glutes, and the hamstrings.