While the workout itself is responsible for stimulating changes in your body; it is actually your body itself that produces those changes. We must always remember that the changes we are asking the body to make are metabolically expensive. Let us say, for example, that we want to add a pound of muscle to your body.
Picture a pound of ground beef at the grocery store. That is a lot of tissue for your body to synthesize. For your body to mobilize the necessary hormones and nutrients to serve the DNA-driven process of protein synthesis, it will require something very basic: time.
How much time is a critically important issue. Exercise can not only serve to stimulate physical adaptations, it can prevent them. Stated differently, if you bring the exercise stimulus back to the body before it has had time to make its adaptation, you will actually interfere with and prevent the response from occurring