This post covers what kiai is, its purposes, whether it can improve the power of your techniques, and how you should do it in your kihon, karate, and kumite practice.

Table of Contents

What is kiai?

Kiai (気合) is a shout, scream or battle cry that martial artists make when they perform a technique usually at the climactic moment of a battle.

Ki (気) means energy and ai (合) means to meet, join or unite, so the word kiai itself means the joining or unification of all energy sources in your body. When you kiai, the aim, therefore, is to bring out all the stored energy you have and transfer it to your opponent at the moment you deliver a technique.

How to kiai?

When you kiai, you don’t say the word “kiai” but instead utter a sound like haii, ayee, eee-yah, hi-yah, hei-yah, or aai-yah that originates from your abdomen.

If you are new to kiai, here is how to do it.

First, imagine you are being punched in the stomach by someone. Now try to tense or harden your stomach and, at the same time, force the air out from your abdomen with an open mouth. Repeat this practice many times until it becomes natural to you. If you practice alone, you can interlock your fingers to strike your abdomen with both palms and practice exhaling and tensing your stomach at the same time. If you have a partner, ask them to punch you in the stomach while practicing it.

After that, add whatever sound that is natural to you (hiy-ah, eee-yah or aai-yah) while breathing out from your abdomen. Your kiai should be short and ear-piercing loud. Again, practice this until everything becomes natural to you. This is your basic kiai form.

Last, once you get the above right with a lot of practice, add a technique at the same time as the kiai. You should visualize that you are utilizing all of your energy to deliver the best technique you possibly can that is capable of finishing off your opponent right there and then.

Purposes of kiai

Kiai is said to have the following benefits in your karate:

  • Increasing the power of your techniques. There is an argument that the power of your technique will be higher when you perform a technique with a kiai than when you do it without a kiai. We will look at research evidence on this topic below
  • Helping you breathe better. Sometimes you may hold up too much tension in your body when you practice and forget to breathe. But if you have to kiai every 5 or 10 techniques, you will breathe out a lot more and relax your body (you certainly can’t kiai with a closed mouth)
  • Protecting you from an attack. When you’re launching an attack is also the time you are most vulnerable to counter-attack. However, if you kiai at the moment of your offensive technique, you will tighten up the abdominal area and harden your body, therefore protecting yourself somewhat from simultaneous counter-attacks
  • Bringing out your fighting spirit. The simple kiai has the ability to instantly lift up the spirit of every karateka. If you doubt it, just compare a class where everyone is practicing quietly to a class where everyone kiai with every technique they perform. There will be a marked difference in the training spirit you witness on the dojo floor
  • Startling or frightening an opponent. A loud piercing kiai can startle or threaten your opponent, giving you a brief advantage to deliver decisive attacks when the opponent is not yet ready.

If you train in karate, you will have already seen kiai in practice. We kiai a lot including our kihon training, kata performance, sparring, and competitions.

In kumite tournaments, how you kiai will be taken into consideration in judging your kata performance as well as scoring you for a technique in kumite. I was told by an instructor that, in a tournament, you need to kiai with every attack to bring attention to your techniques and improve the chance of scoring a point.

What is kiai-jutsu?

To some people, kiai is an art and there is indeed an art called “kiai-jutsu” or “the art of kiai” practiced by some Japanese martial artist masters since as early as the 1910s.

There is a belief that a right kiai can gather up dispersed energy around your body and be used to paralyze, knock back, or injure an opponent or even make them become unconscious. Kiai-jutsu masters are said to be able to heal sick or injured people as well with their kiai by transferring energy to them.

Christopher Caile, the founder and Editor-in-Chief of, who has over 50 years of karate and other martial arts training recounts the following incident that he personally witnessed.

The year was 1961. I was in Japan studying karate with Kancho Mas Oyama, the founder of Kyokushinkai karate. After practice one evening Oyama and I made our way along a dirt street on the outskirts of Tokyo. We were heading toward a Korean restaurant, a favorite of his where we often ate. It was getting dark and as we approached the restaurant in our path were several young men jostling and pushing each other. Suddenly the group seemed to lurch toward us. Oyama stopped and then uttered a short, powerful sound, something between a grunt and a soft shout. The youths froze. All action stopped, their bodies seemingly frozen, movement suspended as if energy had been sucked out of their limbs.

Christopher Caile

Earnest John Harrison (1873-1961), a martial artist and prolific writer who lived and trained in Japan for many years, also mentions some instances of the mystical power of kiai in his book “The Fighting Spirit of Japan” which was first published in 1912.

The child was still conscious and could obey instructions. She was placed on the mats at a little distance in front of the operator who fixed his eyes upon her, emitted the kiai, and swept down his arm. On the instant the flow from one nostril entirely ceased, and that from the other was reduced to a slow dribble. A second kiai removed even these traces of the trouble, and the cure was complete. From that day onward the child was never again bothered with bleeding from the nose…

Yagyu Matajuro [a son of the celebrated fencing-master Yagyu Hida-no-Kami] looked out into the garden where he saw a few sparrows perched on the branch of a tall pine-tree, and fixing his steadfast gaze on the birds gave utterance to the kiai shout, whereupon the sparrows fell to the ground insensible. When he relaxed the kiai the birds regained consciousness and flew away… This particular feat is known in the Japanese fencing schools as toate-no-jutsu, or “the art of striking at a distance”…

Yamamoto Kausuke, a celebrated strategist who served Takeda Shingen prior to Hideyoshi’s invasion of Korea, was one day passing through a mountain forest when a pack of hungry wolves suddenly made their appearance and surrounded him. On the impulse of the moment Kausuke intended to cut the animals down singly, and to that end placed his hand on the hilt of his sword, but on second thoughts refrained, as he concluded that it would be a disgrace to the honour of a samurai to use such a weapon against these animals. Instead he calmly clenched his fists with the thumbs held underneath the other fingers … and coolly passed through the pack of wolves. The wolves appeared to be taken aback by the composure and dignified air of Kausuke and took to their heels.

E.J. Harrison

Motobu Choki (1870-1944), an Okinawan karate master, also mentions the following about one of his teachers, Sakuma Sensei who was a pre-eminent Shuri-te master and contemporary of Sokon Matsumura sensei.

Another revered martial artist was Sakuma. It is said that he could jump into a well and shimmy up or down using only the strength of his legs to support his weight without ever falling into the water below. Remembered for his feats of strength, Sakuma could also snap a tightly bound rope holding large straw mats around his torso by tightening his muscles and giving a fierce kiai.

Motobu Choki

Clearly, kiai was a feature of traditional Okinawan karate and was not added for demonstration purposes after karate was introduced to the public as some sources had claimed.

Does kiai improve your performance according to research?

Some researchers have looked into how kiai affects athletic performances and the findings are mixed.

Elite tennis players are known to grunt as they strike the ball and researchers from the University of Nebraska have found that grunting actually increases groundstroke velocity by 3.8% while not impairing any oxygen consumption. The authors suggest that grunting could be used as a potential means of enhancing sports performance.

The kiap (an yell in Taekwondo that is equivalent to kiai) has also been found to improve strength and performance of both martial artists and novices.

However, in another study that investigates the effect of kiai on the performance of vertical jumps, and reaction time for punches and kicks, no significant differences were found between kiai and control conditions.

There may be more research on the kiai topic published in Japanese but the above is what I could find that has been published in English.

When and how should you kiai?

I have not studied kiai-jutsu and I know next to nothing about the art of kiai so in the section below I’ll share my personal view on how kiai should be used in karate training.


When you practice basic techniques or kumite drills, most of the time, I think your focus should be on the techniques and how you can improve them. You would want to listen to your body and feel how the power is being generated. You would want to check if there is any significant tension in your body. You would want to make sure you are using your core in all movements and there is a good connection between the core and your limbs. You would want to vary the way you perform a technique and see whether there is any difference in the output. On those occasions, I don’t think you want to kiai. And most of your training should be like this: finding out how to best use your body to generate powerful techniques.

However, sometimes, you can just let your body do what it has learned to do and visualize that you are in a life-or-death situation and you are putting everything you have into the technique to finish off an opponent. You are delivering a killing blow (ikken hisatsu). In those cases, your kiai will come out naturally and I do think it will increase the power of your technique.

I understand that karate instructors often want to push their students and lift up their training spirit when asking them to kiai but I do think kiai is overused sometimes. Kiai at the end of a series of techniques is fine but asking students to kiai with every technique while doing hundreds of them means that they are all empty or fake kiai with no intention or meaning whatsoever. You cannot possibly ask them to put 100% of their energy into every technique for two hours.


When you perform kata, kiai is like the highlight of a kata and it needs to be delivered believably with good martial spirit and accompanied by clean and powerful techniques.

Like in kihon practice, in order for kiai to have a positive impact on your techniques and kata performance, you need to get the mindset right first. You need to visualize that you are actually fighting an invisible opponent and you are harnessing all the hidden energy you’ve got to transfer it to the opponent at the moment of kiai.

Substance over form should be your transcendent principle whether you are delivering a technique or a spirited shout kiai and whether you are practicing on your own or demonstrating in front of a grading panel or judges.


There is an overuse of kiai in sports karate competitions today because of the way it grabs the attention of the judges and affects the scoreline.

But in real life, too much shouting and yelling means empty kiai that does nothing to improve the power of your techniques or give you a better chance to win a fight.

Because true kiai means uniting all stored energy (ki or qi) in your body and delivering it to an opponent, you can’t constantly do that because your energy will be depleted very quickly. In addition, real-life sparring will also drain your energy a lot more quickly compared to practice sparring in the dojo, so it’s better to save that kiai for the right moment. Excessive kiai also means it loses the element of surprise.

Use kiai only when you need to startle your opponent or when you want to go all out and throw everything you’ve got at the opponent to finish him or her off. In the latter case, your kiai can have a profound effect on your fighting spirit. Here you are, a lion roaring before it pounces on its prey, you are proactive, you have no self-doubt, you are mighty and fearless, and you are giving your all.

I don’t think you can plan when to kiai in a real fight, it will happen naturally when you sense that it is the right moment to muster all the energy and power you’ve got.

Miyamoto Musashi (1584 – 13 June 1645), considered one of the greatest swordsmen and most celebrated samurai of all time, mentioned three types of battle cries in the Book of Five Rings.

To shout at your opponent does not mean that you are yelling all the time. You should not shout in time with your striking rhythm. Shouts are made before and after the fact. When it is uncertain where you will attack, then it is feasible to let out a cry beforehand. There is also the post-attack cry in which you bellow after delivering a blow. This is the “after shout.” There is the shout Ei, which can be made loudly or quietly. There is also the shout Maitta. It depends on the situation surrounding the attack. An “accompanying” shout, which is tied to a strike when both rhythms are similar, is Ya, and is for overriding the opponent’s cadence. This shout is made inside the mouth, in your heart so that nobody can hear it. These are the three cries of “before,” “after” and “within.” It may seem that shouting is unnecessary. Nevertheless, as we shout against the wind, waves, and fire on the battlefield, we must also shout down the enemy’s vitality.


Although some call kiai-jutsu pseudo-science and BS, I have no doubt kiai done in the right way can generate unbelievable power (after all, it’s been proven that even an opera singer’s voice could shatter glass). However, it is unfortunate that most of us training in karate today are not able to unlock even a fraction of the potential power of kiai. Most karate instructors are not even aware of the existence of a field of study called kia-jutsu and genuine kiai-jutsu seems to be no longer practiced today. Instead what we have are some self-claimed kiai-jutsu masters who fool themselves and their students.

Why Is Kihon So Important in Karate?

Why Kata and Bunkai Should Be Consistent

“Karate Belly” and the Physical Activity Paradox

Is Karate Good for Weight Loss?

Karate Vs Boxing: Which One Should You Learn?

Motobu Choki’s Training Methods



Kiai – Wikipedia

Kiai Jutsu: The Shout Used As A Weapon

Kiai Jutsu

Kiai Jutsu – Martial Arts Planet

Other references as noted in the post