In reading Bruce Lee's writings and listening to the few interviews he gave in his life, bio-mechanics in order to acheive the pinnacle of Martial Arts, Jeet Kune Do.
What is bio-mechanics? Bio-mechanics is the study of forces and how they affect the human body. Just from the definition it should be obvious why this is important in the Martial Arts.
Bruce Lee understood why bio-mechanics are important. Because it does not matter if you are big, tall, man, or woman, the human body works exactly the same.