Why are there only straight punches in karate? The short answer is that straight punches are the most effective types of punches. It is well known in weightlifting that straight lines are the most effective directions to lift a weight. The same applies for punches. A straight punch will always be faster and more direct than say a hook or uppercut. However, the reason why a straight punch is considered more effective is not just a result of its direction, but also of our perception of it. By this I mean that our ability to accurately see and predict the trajectory of a straight punch is physically harder than that of a hook. This is the longer answer to the question of why there are only straight punches in karate.

Part 1 Focussing light (has two subparts)

The lens focuses the light on the retinal wall at the back of the eye so that the main point of focus is concentrated on a region called the Fovea. This area of the retina has a concentration of special light receptor cells that allow us to see objects in sharp focus (like we have to do when reading or looking at an object in detail). In other words it is the part of the eye that allows us to get a really clear picture. When the light from an object converges on any other point than the retinal wall, either in front or behind, then the object appears blurry.

Secondly, these diagrams show how the lens focuses the light from different distances.

It stretches or shrinks depending on what we are looking at. The muscles at the edge of the lens contract to relax the fibres causing the lens to round up so we can focus light from an object that is close directly on the Fovea or stretch it out so that we can focus light from and object far away on the Fovea. When an object is close we have to bend the light more to get it in focus than when an object is far away. The amount that we are able to bend the light or stop bending it has limits though. For example when one`s lens is fully stretched out one still bend the light too much when looking at objects far away. This means that the light converges at a point before the retinal wall and the Fovea and therefore the objects far away appear blurry. This is why a short-sighted person have to wear glasses to bend the light the opposite direction so that his/her lens can focus the light on the right place on their retina (what is called myopia) ( Long sighted people have the opposite problem for object close up, like reading. They can not bend the light enough. There glasses bend the light a little bit more before their lens bends the light focusing it on the retina.

So when we think of a punch which is coming very close very fast then we see that the lens muscles have to adjust very fast to change the lens shape to keep the light focused on the retina. When the object is closer to the point between our two eyes then we have to bend the light to an even greater angle to keep the light focused on the retina from a source that our lens is not optimally configured to bend light from. We then have to move our eyeball to compensate for the lens. Our eyes are not used to moving both eyes towards our nose at the same time and are not efficient at it. In other word our lens muscles and eyeball muscles have to work harder to keep things in focus at an angle that they are not optimised for.

Part 2 Judging distance
This section is associated with how we see in 3D. We have two eyes that receive slightly different 2D images of the world. The brain interprets the amount of difference between these two images to tell us how far an object is away from us. This stereoscopic vision allows us to judge distances very precisely and is why most predatory animals have their two eyes facing forward. They exchanged the ability to see behind them for the ability to get a better judgment of distance. Now when there is a very big difference between the two images received by the eyes the brain normally discounts one of the images and only uses the other. You can test this by looking right and left without moving your head. Focus on an object and alternatively close one eye and then the other. You will notice that when you look left the left eye’s image is dominant and the right eye is actually looking at the inside of your nose. The opposite is true when you look right.

When we are looking forward the brain is trying to take equal weight from both images from both eyes. This is OK when there is not a very large difference between the images the brain receives. You can test this by focusing on an object far away and closing one eye and the closing the other. The object appears to move slightly and the brain can construct a 3D composite image in our mind helping us judge the distance and shape. When we do this with an object that is very close the difference received by our eyes are very different. You can test this by focusing on your finger directly in front of your nose and closing one eye then the other. The finger appears to jump position a lot as the image received between each eye is very different. The brain finds it difficult to reconstruct such different images into a 3D composite image so that distance can be judged.
In an example of a punch directly along the center line, the brain can not accurately interpret the speed and distance of the fist as, firstly, it has difficulty focusing the light on the retina that closes in at that angle to get a clear image (part1) and secondly, neither eye is dominant when looking straight ahead. Images between the eyes close in sent to the brain by both eyes are too different for us to construct a 3D image of the object to allow use to accurately judge speed and distance. We duck or block at the wrong time and get hit.

And that, in short, is why a straight punch seems faster and harder to avoid than a hook as our ability to accurately judge its distance and speed is impaired by the straight punch`s angle and direction. Now, while this explains the efficiency of straight punches, it does not necessarily explain why there are only straight punches in karate. I believe there are only straight punches in karate for the following reasons:

1. Karate is supposed to be able to incapacitate an opponent with one punch. This is ingrained in karate through the use of kiyai and the emphasis on explosiveness. Given that a straight punch is the most effective, it therefore makes sense to make this the primary attack of this explosive martial art. This is certainly the case as pertains to kumite in which it is form and speed that determines the point (not strength or damage).

2. As most karate teachers will inform you, karate is built so that a smaller person can defeat a larger one. i.e., it is a martial art based on the principle that size or strength should not be the reason why someone loses/wins a fight. To this end, utilizing straight punches makes sense as they will allow people of inferior strength or physique land more effective punches.

To conclude, I believe karate only uses straight punches as these are harder to react to, faster, and therefore more likely to land. This is crucial to a martial art as karate which emphasizes speed, explosiveness, and effective self-defense.

Written by Dr Kieran Mcgourty
Edited by Alex Mellbye