365 Ways #131–Crunches as a sedative

#131–whenever there occurs a contraction on one side of a joint, there must also occur a (relatively) equal and opposing contraction by the antagonist(s) or opposing muscle group(s) on the other side of the joint to create stability. Thus, crunches from the floor, which millions of people do each day to help stabilize their back (or in a vain attempt at a 6-pack), actually contribute to dysfunction since the opposing muscle group doesn’t need to fire. The floor is doing the stabilizing!

Additionally, you can only flex the spine approximately 30 degrees. But you can extend the spine 45 degrees and more. So you're missing more than half the range of motion. If you exercise a muscle in a shortened range of motion, that muscle will drop sarcomeres and become chronically shortened. In contrast, the opposing muscle groups (the extensors in this case) get held in a stretched position. Static stretching of 30s or longer can inhibit the muscle(s) being stretched. Thus, keeping your extensors (i.e. your back) in a stretched position 24/7 puts these important postural muscles in a coma. But that's o.k. I hear there's an open casting call for a remake of The Hunchback of Notre Dame.