Shotokan Sensei teach many variations of this punch. As your karate should be ever evolving , the punch described below, is the way I am practicing at the moment.
This article focuses mainly on the basic fundamentals of the shotokan straight punch. A basic choku zuki video can be found at the bottom of this article, there will be a more advanced video to follow.
Choku Zuki (Straight Punch)
The first punch practiced in Shotokan is choku zuki or straight punch from Heikō-dachi (parallel stance).
Starting from a natural stance (shizentai), feet hip width, toes facing forward with the left arm out and the right arm at the side of the body, ready to punch (see image 1).
1. Use the whole body to punch!!!
Many karateka will only use the arms when punching, but tremendous power can be generated when the whole body is utilised.
Start the right arm punch from the right leg!
Load the punching arm by slightly squeezing the right rib cage down. To begin with, you can exagerate this by also dropping the right shoulder slightly down. Obviously this dropping of the right side is not shown when punching properly.
2. Push through the right leg, then drive with the hip, next use the rib cage and shoulder then finally the arm. So the body throws the punch and not the arm!
3. Just before the right punch makes impact, the whole right side of the body is forward, pushing the punch at high speed towards the target.
4. Just as the punch makes impact, the right side of the body and hip, snaps sharply back, whilst the left hip snaps forward sharply. The arm continues to full extension and there should be a few inches natural recoil of the punching arm.
5. Breathing should be natural, silent and hidden. Breath out on the punch.
Choku Zuki Video Tutorial.