Why do boxers exhale and “hiss” when punching?

If you’ve ever been in a boxing gym, one of the sounds you’re most likely to hear, apart from the resonating thuds of the heavy bags being hit, is the hissing sound made by the fighters each time they throw a heavy punch.

This sound is generated by the boxer exhaling forcefully through their mouth and through their mouthguard.  The tongue rests on the roof of the mouth and after each punch only lets out a small amount of air.  In this way, the tongue acts like a pressure valve, controlling the amount of air released.  It’s this release of pressure each time the tongue lets out air that creates the hissing sound.

Throughout this breathing technique, the mouth remains closed.  As a boxer, you don’t want to exhale with an open mouth as you’re likely to have your jaw broken if you’re hit at the same time as breathing out with your mouth open.

It’s a very common phenomena and I’ve often wondered why boxers exhale and “hiss” when punching.  After a bit of research, this is what I’ve found out. 

Why do boxers make sounds when they punch?

To tighten the core.  One of the main reasons for employing this technique is to help tense the abs.  When the tongue blocks the outflow of air in this way, intra abdominal pressure is created.  This helps to create rigidity in the core and to tense the abs.

You can try this yourself. Simply try to tense your abdominal muscles (your abs) as hard as possible.  If you let this happen quite naturally, you will find that you breathe out, expelling the air from your lungs.  Less than a second later, your tongue will rise to the top of your mouth to create the pressure in the core and your abs will tense.  If you poke your stomach with your fingers, you’ll find that it’s quite solid.

As a boxer this is clearly desirable.  A fighter is often most vulnerable when they’ve just thrown a punch.  Indeed, this is when they might be susceptible to a counter punch.  If this punch from the opponent is aimed at their stomach it could mean the end of the fight unless the individual’s core is tightened and braced for any potential blows.

By using this breathing technique, the fighter is able to throw punches whilst bracing their core to be able to withstand any counter punches.


Removes excess air from the lungs.  If there is a counter punch to the stomach then the last thing you want is to have are lungs full of air.  You’re likely to have the wind knocked out of you in this event which is extremely debilitating.  You’ll end up collapsed on the floor gasping for oxygen.


To add power to the technique.  If you look a powerlifting or strongman competitions, the participants  will exhale forcefully whenever they are in the process of lifting a heavy object.

This outwards breath allows the individual to coordinate all the muscles of the body, adding power to the technique.

It’s not just boxer who use the power of the breath to enhance the power of their strikes.  It’s a common technique amongst a lot of martial artists.

Take Karate for instance. I’m sure we’re all familiar with the image of rows of Karate students simultaneously performing the same sequence of strikes and yelling after each punch.

This ‘yell’ is actually called a kiai and is designed to increase the power of each technique.  

In martial arts, the kiai has the added advantage of summoning an element of controlled aggression within the practitioner, adding further strength to the technique. 

The kiai also acts to intimidate an opponent.  I think few attackers would expect their victim to start counter attacking whilst yelling at the top of their voice.

The major problem with the kiai is that the shout is  performed with an open mouth.  This means that the jaw is opened and therefore highly vulnerable.  A strong enough strike to the chin during a kiai would result in the jaw fracturing.

Boxers, aware of this issue, keep their mouths closed when they fight and instead forcefully exhale their breath through their mouth guard. They thereby gain all the benefits of exhaling whilst punching without the risk of having their jaw injured is they were to open their mouth.


It regulates breathing.  Exhaling after each punch encourages you to breathe properly.  It allows carbon dioxide to leave the body and, on the inhale, allows you to take in oxygen.  

The tongue on the roof of the mouth stops too much air leaving the body at anyone time.  In this way it acts as a stop valve.  If you didn’t use your tongue in this way then you’d run out of breath very quickly.

In a fast combination of punches there might be a continual light exhale through clamped teeth or it might just be on the last hit.  The fighter may choose not to exhale at all on some shots, such as a light jab.

However, the normal boxing pattern is that the boxer will unleash a combination of punches before moving away and gaining distance to recover and breath to replenish their oxygen supply.

Boxers will hiss and forcefully exhale after each punch even when training on a heavy bag where there is no risk of a counter punch.  This is because they want to develop muscle memory so that the breathing becomes instinctive and they no longer have to think about the technique consciously.  It just becomes a natural part of their fighting repertoire.


In summary…


There are a number of reasons why boxers exhale and “hiss” when punching: it tightens the core, removes excess air from the lungs, adds power to the technique and regulates breathing.

It’s well worth incorporating this technique when you practise on your heavy bag.  It’s that crucial component that could add that extra zing to your fighting technique.

Happy training!!

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