When you watch a full contact martial arts match, in any discipline, you may be sometimes left wondering how the judge knew whether a particular strike was worth a point. Up to relatively recently, judges relied on their experience. It they had a lot of experience, they looked for a strike that would cause the opponent to be unable to counterattack, or at least obviously slowed in his attempt. There was a direct connection between what a judge thought was a "point" strike and what constitutes effective fighting. In Tae Kwon Do, for example, this used to be expressed in the rules as follows: Points are awarded when permitted techniques deliver full force, abrupt displacement and trembling shock to the legal scoring areas of the body. Since the goal in full contact martial arts is not to kill, main, or even seriously injure the opponent, techniques and the areas available for contact are limited and excessive force is penalized. So, exactly how does a judge know when the technique is hard enough?

These days, the rules offer even less guidance to judges for determining effective fighting. For example, today's Olympic Tae Kwon Do rules state: "Points shall be awarded when permitted techniques are delivered accurately and powerfully to the legal scoring areas of the body." This doesn't say anything about the state of the opponent, such as, "Is he experiencing trembling shock?" Neither does it bring into question whether he would be able to counterattack. In fact, using the written rule alone as a guide (and after all, that is the point of having written rules, isn't it?) the only criteria is accuracy, and power rather than effective fighting. Given that, a technological solution to measuring power and accuracy makes sense.

Trying to measure the force of a blow delivered by a martial arts fighter is not a really new idea. Back in 2004, some folks at Stanford used Wi-Fi together with a system of specialized sensors to measure the force of the blows martial arts opponents land on each other. Wireless sensors, implanted in the fighting gear worn by competitors, work by converting the force from a punch or kick into an electrical signal. The idea was to figure out if a blow was hard enough and accurate enough to count as a point. Stanford said that "Currently there is an inherent bias against punches as a scoring implement as most judges do not believe that punches deliver the same amount of force as a kick. With our system, we are able to establish how much force the punch was able to deliver."

What the Stanford folks said is correct as far as it goes. First, many martial arts judges do, in fact, believe that punches deliver less force than a kick, and secondly, Stanford's system does accurately measure force. Here's what's wrong with that. The rules used to instruct judges to look for a response from the person receiving the punch or kick. They looked for effective fighting--The exact amount of force wasn't what was being judged. The important thing was the effect on the opponent. If you are in a real fight, no one cares whether a punch or a kick measured 1500 pounds of force if your opponent is still able to hit you back. If he still has good balance, fast reflexes, and a strong punch or kick, then you didn't hit him hard enough. The fact is that a martial arts fighter will respond to a punch delivered with a given force depending on his training. How much muscular cover does he have on that area of his frame? What is his bone density? How much control does he have over his body's response to trauma? Developing these traits is how a fighter trains for effective fighting. The results of training, experience, and inborn ability determine how good a fighter your opponent is. When points are awarded on the basis on force measured by a sensor on a chest protector, you might as well be fighting with a crash dummy, because the ability, conditioning, and training of your opponent has ceased to matter.