↩ Back

# Why so few injuries?

## Intro

Breaking hard objects appears painful and dangerous, so why are there so few injuries due to breaking. Training is the most important reason. ANYONE can break one, 1 x 12 pine board with a punch, usually with no injury. If you break a lot or you break greater thicknesses, then proper training is required. The training teaches you how to form your striking hand, keep your wrist locked, etc. But there is something else behind the scene that makes injury-free breaking possible.

## Speed

One key to understanding breaking is a basic principle of motion: the more momentum an object has, the more force it can generate. For example, when breaking a brick with a punch, the fist reaches a speed of about 11 meters per second (24 miles per hour). At this speed, the hand exerts a whopping force of 3,000 Newtons or 675 pounds. When that amount of force is concentrated into an area as small as a fist will easily break a brick. Human bones can resist 40 times more stress than a brick.

In the late 1970s, Stephen Wilk and Ronald McNair, the scientist-astronaut who later died tragically when the space shuttle Challenger exploded, set up a strobe light that flashed at either 60 or 120 times per second. They photographed McNair and others performing various kicks and punches. Once the film was developed, they could calculate the speed of a punch by counting how many times the strobe flashed until the fist or foot hit its target.

They found that beginning martial arts students throw a punch at about 20 feet per second, enough to break a one-inch board. But a black belt like McNair could punch at 46 feet per second. At that speed, a 1 1/2-pound hand can deliver up to 2,800 Newtons. Splitting a typical concrete slab that is 1 1/2 inches thick takes on average only 1,900 Newtons.

To attain more speed in your punches, you must add force to them. To generate more force and thus more speed, you must strengthen and tone your muscles and body, and coordinate all your body movements. This takes lots of training.

↩ Back