The main goal of flexibility training is to restore posture to more ideal realms. This involves unlocking joints and looking to return the spine to a more ideal alignment through stretching of the muscles and fascia. When this happens you can see remarkable improvements in strength and decreases in pain within minutes.
However, for this to happen you have to get outside of the the usual training ideas. For example – it has nothing to do with hamstring stretches. The warm up sequences show you a little about preparing for sprint sessions and so forth.