Kung fu fighting is the demonstration of all that we have learned in the other non-combat practices that we do. It's not that we learn specific fighting moves at all, rather, we practice our breathing and static poses, and this in turn improves our overall physical state, and the result is improved performance in kung fu fighting with our classmates. As you can imagine, many years of this type of practice will have some effects on the body. Some of these are obvious and physical, but whether there are other less obvious and specific effects is not easily measurable with present technologies.   However, Kung Fu fighting is one way to discern the level of Chi Gong a practitioner has achieved, the physical manifestation of their internal level is measurable, speed and power.