I think we can all agree that the human body is a truly amazing thing. There is seemingly no end to the fascinating characteristics of all of its systems, with organs, blood, bones, and, of course, the brain. Yet, as amazing as it is, our bodies are easily tricked. When you train your body, it "thinks" it literally won't survive if it doesn't change in response to a training stimulus.
Think about that. Your body's various systems have a one-track mind: survival. They will react to anything based on that goal. Read more >> about Running in the 'Meda: Adaptations