Random Bits #1 The Subtleties of Shivering

So most of us know shivering as the body's way of keeping us warm by using our muscles to generate heat. What you may not know is what I learned today. What actually generates the heat is not a rapid contraction and relaxation of the muscle- rather it is the isometric contraction (tightening of the muscle fibers without movement of a joint). For example holding yourself up in position about to do a push up, or clenching your jaw- that clenching uses energy and generates heat to keep you warm. The shivering is the reaction of your muscle to being held so long in that contracted state. So to use the push up example, if you held that position a long time or any other static position where you are keeping a muscle tight, you would eventually start to shake. So the next time you are cold take notice to whether your jaw is clenched BEFORE you start to shiver!