Dewey Nielson is a beast. Check out his youtube videos and awesome video on crawling mechanics in video below.
Dr. Stuart McGill i a professor of spine biomechanics at the University of Waterloo (Waterloo, ON, Canada). He is an expert many elite athletes, coaches, legal experts and even government officials turn to for difficult back cases.
Dr. Stuart McGill top 3 recommendations for a healthy back are
1. Bird Dog
2. Side Plank
3. Curl Ups
Check Out videos Below for some detailed information al of these exercises.