For the past year or so, I've been picking up books on the human body and how it works so I can better understand how it functions and how it relates to my physical culture hobby. In the past month, I've picked up two on motion and muscle which have been extremely revealing in terms of learning about exercise. One thing that has leaped out at me that I want to write a bit about is the arm.
A while back at Transformetrics.com, I posted about how I feel like one of the key differences between the weightlifted arm and the BW-exercised arm is that the former tends to be bulkier and more "cut" while the latter has a leaner, more slender look to it. So, the question is, which form is more functional? After all, I'm more about how well it works rather than how good it looks.
It didn't come as a surprise when the information that I've gathered so far suggests that the modern standard in weightlifted arms is may well be less functional despite looking more impressive. There are some logical and anatomical reasons that I base this upon. To understand these, we have to understand when it comes to movement, the body is either set up for power or precision based upon need. The more powerful the movement, the less precise it is and vice-versa.
All muscles fibers are bound together in a series of bundles. These bundles are then arranged a in a certain manner, depending on how much power or precision is needed. When precision is needed, they are laid in a parallel manner. When they need a more powerful contraction, they are arranged in a fashion similar to the make-up of a feather (in fact, the term for this, pennate fiber, means "feather" fiber). The muscles of the arm are almost entirely parallel fiber.
The precision construction doesn't end there. It continues in with the types of levers that the muscles and bones form in the arms. Many of the levers of the arm are third-class levers, similar to tweezers, which are obviously more precise than a second-class lever, like a wheel barrow (or in the case of the body, the foot).
So, the desire to bulk up the arm misses the point of the arm. It is important to have power in them but the arms race that has pushed many to 20+ inch upper arms diminishes the usefulness of the arm. One thing that I learned about the arm from boxing is that power isn't generated from the arm, it is transferred through it. The arm is designed to be a precise tool more than a powerful one. To make it a functional part, it should be trained as such. It may not be sexy but it makes more sense.