Very early in their training, karate students are taught a basic punch called oizuki (lunge punch). It is used frequently in basics, bunkai (applications) and kata, and is usually executed in hangetsu-dachi (the Ryusei forward stance). The beginning student should step first and then punch – the base must set before the punch is executed. Other factors to keep in mind include balance, direction and distance.

The basic oizuki is done with a separate step,
to set the base, and then punch.

As the student becomes intermediate (4th to 2nd kyu), they should begin to use rotational hip action to add power to the basic step and punch. At this point, the step should become more of a lunge. Rather than breaking down the motion into separate step and punch motions, the student must bring it all together in a single, fast motion, getting power from the forward thrust of the body. All to often I have seen students continue to step with this punch when a lunge is necessary to make it effective. A step is far too slow for this purpose.

As the student becomes advanced (1st kyu and shodan), the oi-zuki must become a part of the their fundamental arsenal. Now the karateka must bring the basic concepts they have learned into a single focus, to make the punch really effective. They should start to execute the punch slightly before the step, with the hip remaining relaxed until the last moment. Just before impact all the factors – the step, punch, hips, balance and kime (focus) – come together to create a truly fast, powerful technique. It is important for the student to stay relaxed until the moment before the technique’s completion. They should also start to realize the important role the punch plays in learning to execute explosive movement from a standing start.

As the student advances in the black belt ranks, this punch must become even more explosive and realistic. All the components should be there as one: lunge, hip, punch, shime (contraction), shibori (wringing), kime, zanshin (awareness of opponent) and eventually hakkei (unleashing of internal energy).

The advanced oizuki explodes out of a standing
start, uniting all the elements of the technique in
one move, including hips, kime, lunge and punch.

I like to compare the technique at this stage to a bullwhip. The whip is a single entity but it is composed of a handle and a long rawhide length that extends to the tip. The tip cannot strike by itself, nor can the rest of the rawhide length or handle. However, when these parts work together – the handle snapping its energy along the length of rawhide and exploding out the tip – a flawless technique is executed. Although the whip is supple and soft, it delivers a powerful, penetrating impact. The karate student must train hard to achieve a whip-like power in their oizuki and other karate techniques.

—Peter Zehr, 4th Dan, Grey-Bruce Ryusei Karate Clubs