A few months ago a question came up during a Kung Fu class:
When throwing punches in training, why is it so important to bring the fists all the way back to the waist? As Shi-fu Tim demonstrates, in a sparring or fighting situation you would virtually never bring the fists back that far because it would leave the body open and vulnerable to attack; he shows that it is generally best to keep the fists out in front of the body for protection and availability.
It may seem at first glance that we are looking at a conflicting set of ideas between training and fighting, but things are not always as they seem.
As a person who studies bodies and movement patterns for a living, I was intrigued by the question, and it got me thinking.
Perhaps it would be easiest to think of the body as a slingshot and the muscles as the elastic bands. If you're firing a slingshot, the more tension you put on the elastic band (without breaking it), the more power you get when you let it go. The mechanism for throwing a punch is much the same.
To translate this back to the human body, our muscles are a complex network of elastic bands that work together with the skeleton to create movement. In training, when we bring the fists back to the waist to prepare to throw a punch, we bring the muscles to their end range - pulling them back as far as they can go.
Technically this position activates shoulder and spinal stabilizing muscles (the "sling" of the slingshot), and puts the arm in a position so that when released forward for a punch, gives maximum potential for contraction of Serratus Anterior and Pectoralis Major, and Subscapularis (the "shot" of the slingshot).
The cool thing about the body is that the more we train our maximum range of movement, the more we can affect strength at any range. A muscle becomes strongest and healthiest only when we can take it through its full potential range of movement - because we challenge all the muscles fibers maximally. Strength through the full range means two key things for all muscles: better protection against injury and more power.
Training is about being prepared.
So even though we do not frequently use full range of motion in sparring or fighting situations, we are wise to be equipped with more than we need.