Oshi-zuki, or push punch (think the sequence in Chinto), is often taught as two oizuki (lunge punches) in a row. While this the right way to learn it, oshi-zuki is really much harder than this to do properly, and has applications that aren’t readily apparent in the basic execution. In fact, it’s not really a punch at all, but a building block to something better.

A basic oshi-zuki is performed as two consecutive lunge punches.

First let us examine the punch step by step. In an article I wrote for Ryushu last year ("Anatomy of an Oizuki"), I spoke about the need for speed when executing a lunge punch. Well, this is true for the first part of the oshi-zuki, too. When the punch is launched, you have to explode into the step, using your hip and shime/shibori at the end. However, unlike oizuki, this is not the end of the technique. Having impaled your intended target on the end of your fist, is what you are doing next taking another quick step and to push your opponent away, setting him up for a second, finishing punch? This seems kind of awkward. While you find oshi-zuki in advanced Ryusei kata, at first glance the technique seems to be weak and ineffective.

To do an advanced oshi-zuki, you should explode into the motion, and the first punch should flow into the next.

However, I believe that oshi-zuki is a setup for an entering, throwing or controlling technique. So thinking that way, you use the first punch to “soften” your opponent, then you use the next step to control the counterattack, or to move into a throwing position, since you are inside your opponent’s space. So the second punch is not necessarily a punch.

You cannot achieve this more advanced use of oshi-zuki by merely performing two stepping punches. The second “punch” must have energy flowing from the first, allowing you to punch, block, grab, throw or any combination of these.

In application. the first punch of an oshi-zuki can be used to set up a throw, joint lock, block or other controlling technique. So the second "punch" is not really a punch.

The footwork also becomes important in how you cover the distance between you and your opponent. It can be a full step, half step, reverse step, and so on, depending on the situation. You need to practise oshi-zuki many times, linking one technique to the next, to be able to perform it correctly and know its many applications.

—Peter Zehr, 4th Dan, Technical Director of the Grey-Bruce Ryusei Karate Clubs