Back exercises are just as important as abdominal exercises so that we don’t create a muscle imbalance.  I like this video because the beginning arm variations are different and I like the way the instructor cues prone.  She makes key points; such as keeping the head neutral and during swimming having the movement come from the shoulders.  I like to break up side kicks in class and place the prone work inbetween, this way they are never forgotten.  🙂