Body Looseners: Reference: Dreyer, D., & Dreyer, K. (2009). ChiRunning: a revolutionary approach to effortless, injury-free running. New York: Simon & Schuster.

Think of your body as a small engine. When you first start it, you have to let it warm up and idle before you go full throttle. If you start it and try to "gun it," it stalls. Your body is the same way. If you jump straight into running without warming up, you may not die, but your body will more than likely pay the price.