What are diaphragm contractions when we freedive?

When we hold our breath, we all get some form of an urge to breathe. This can manifest itself as in many ways, but one of the most common is in the form of diaphragm contractions. In this article we’re going to look at what cause diaphragm contractions when we hold our breath, how this affects our freediving and ways to manage them.

The first time I ever became aware of freediving contractions was at my first ever freediving competition in 2002 in Cyrpus. The hotel pool was filled with freedivers during most of the day, all practicing static apnea, holding their breath on the surface of the water.

One of the world’s top freedivers, Austrian Herbert Nitsch was training with another top freediver, the Swede Bill Stromberg. Herbert was doing repeated static breath holds of around 7 minutes each. I remember watching as, for the first part of his breath hold his body was completely still. Then a few minutes in, occasionally his upper body would move a little. As the breath hold continued, this movement in his torso got even more violent, as if he was being sick. By the end, this movement engulfed his upper body, all the way up to his head so that Bill, as his buddy, asked him if he wanted him to ‘put my hand on your head to keep it under’!

I had just started to train static apnea the previous year, but I had never experienced anything like this.

What happens in the body when we have a diaphragm contraction?

The urge to breathe when we freedive comes primarily from rising levels of carbon dioxide in the blood. As we have higher levels of carbon dioxide, the body stimulates us to breathe. A diaphragm contraction is simply the movement of the diaphragm, which can be very subtle, almost like a little flutter, or a movement that seems to bend our entire body in half.

Some freedivers say that they never ever get diaphragm contractions when they freedive and some people get them very early on. In my case, they can come on after only a minute and there is no let up. They can be so intense that my whole body bends as if I have been punched in the stomach.

Some freedivers find that after a couple of contractions they can go away for a minute or so, but for me once they are there, they are there to stay.

Why else might we get diaphragm contractions when we freedive?

As well as the build up of CO2, freedivers can also experience diaphragm contractions when they dive deep due to the increases in pressure at depth. Many freedivers experience contractions on their freediving descent which can be very disconcerting as it is not even half way through their dive.

Stress can also contribute to contractions when we freediver as can cold water. If you are freediving in cold water and are stressed, then a very strong diaphragm contraction has the possibility to contribute to a lung injury so it is very important to dive warm and increase depth slowly, always feeling comfortable at the new depth before diving deeper.

How can we stop diaphragm contractions when we freedive?

When I practice static apnea, I try and delay the onset of contractions for as long as possible. About a minute into my breath hold I start concentrating on keeping my body as still as possible and having a very slight tension in my diaphragm, keeping it still.

Another technique to stave off contractions, which is very helpful is to swallow. When I feel I can’t hold the diaphragm contractions off by keeping my body still, I swallow and that buys me another few seconds. However, for me, once they have started, they are impossible to stop coming!

See how strong diaphragm contractions can be

I took these video clips at our pool club with one of our freedivers, Jonathan, who has been freediving for a few years. He is an extreme example of someone who experiences diaphragm contractions very early (a minute into his breath hold) and they come thick and fast until he can bear it no more.

You will see how his whole body is convulsing so much that his feet are bouncing his body off the floor.

Also see that at the end of his breath hold, which was two minutes thirty seconds, he is not hypoxic. This means that his body is not low on oxygen, despite how bad his contractions are. You can see this by the fact that his lips and face are still a healthy pink colour. When freedivers become hypoxic, their lips will usually turn very white, blue or purple.

Another freediver might not have a diaphragm contraction for three or four minutes, however Jonathan’s come very early. Diaphgram contractions are not therefore the best indicators of your hypoxic state.

How to increase CO2 tolerance

It is a false economy to practice any form of over breathing. Over breathing, or hyperventilation, causes levels of CO2 in the blood to reduce, slowing down the arrival of our urge to breathe. This may cause diaphragm contractions to come later, making our breath hold seem easier, however hyperventilation causes oxygen to bond more strongly to haemoglobin (the Bohr affect), raises the heart rate and the rate at which we burn oxygen, reduces blood flow to the brain, and massively increases our risk of blacking out due to the removal of the urge to breathe.

Training the body to get used to high levels of CO2 is the way that we can adapt the body to breath hold and help us experience less diaphragm contractions, or later on.

CO2 tables, apnea walking and other CO2 tolerance exercises are all excellent ways to practice and the most important thing is to keep warm and relaxed and feel comfortable and confident when you freedive. Practicing with an instructor or a buddy you know and trust well, practicing regularly and progressing slowly are the keys to successfully managing diaphragm contractions.

What are are your diaphragm contractions like? Share your experiences below!

Emma Farrell has been freediving since 2000, teaching freediving since 2003 and is the UK’s only Instructor Trainer with AIDA, RAID and SSI. A founding member of the AIDA education commission, she has written courses that are now taught internationally, as well as her own specialist courses, magazine articles and the beautiful book One Breath, a Reflection on Freediving. She has appeared numerous times on television promoting freediving, most notably teaching Hugh Fearnley-Whittingtsall how to freedive for the River Cottage television series. She is a specialist yoga teacher and has taught gold medal winning Olympic athletes across two disciplines how to improve their performance using her unique programme of freediving and yoga techniques. Read more about Emma here.

2017-10-24T10:18:39+01:00

6 Comments

  1. Jessie 02/07/2015 at 2:03 pm - Reply

    Great article!
    I’m still a lousy beginner, but my contractions static differ from those in dynamic. Well, at least, how I feel them in terms of (dis)comfort.
    In static, I tend to be able to stand them. Sometimes, I even enjoy them (in the beginning). It’s weird: as if I get a fresh breath of air with each contraction (every 4-5-6 seconds in the beginning). I have done (dry) breathholds with 2+ min. of contractions.

    In dynamic (with fins) however, my PB is 50m. I keep stopping at 50m, because my contractions start around 30-35 m and get worse very rapidly. Unbearable almost. Maybe I’m swimming too fast, being too tense… (It takes me around 50 sec – 1 min. to do 50m with fins).
    I did do one 50m DYN without contractions, but I have to admit my breathe up involved a bit of hyperventilation. That’s not only cheating, but above and before all: dangerous, I know. Never again, promise!

    So, yes, I’m struggling with contractions as well, especially in DYN. Even though I know it’s not a sign of being really hypoxic… I know all that…

    In short:

    :-/

  2. Jessie 02/07/2015 at 2:04 pm - Reply

    Great article!
    I’m still a lousy beginner, but my contractions in static differ from those in dynamic. Well, at least, how I feel them in terms of (dis)comfort.

    In static, I tend to be able to stand them. Sometimes, I even enjoy them (in the beginning). It’s weird: as if I get a fresh breath of air with each contraction (every 4-5-6 seconds in the beginning). I have done (dry) breathholds with 2+ min. of contractions.

    In dynamic (with fins) however, my PB is 50m. I keep stopping at 50m, because my contractions start around 30-35 m and get worse very rapidly. Unbearable almost. Maybe I’m swimming too fast, being too tense… (It takes me around 50 sec – 1 min. to do 50m with fins).
    I did do one 50m DYN without contractions, but I have to admit my breathe up involved a bit of hyperventilation. That’s not only cheating, but above and before all: dangerous, I know. Never again, promise!

    So, yes, I’m struggling with contractions as well, especially in DYN. Even though I know it’s not a sign of being really hypoxic… I know all that…

    In short:

    :-/

  3. Jessie 02/07/2015 at 2:04 pm - Reply

    Great article!
    I’m still a lousy beginner, but my contractions in static differ from those in dynamic. Well, at least, how I feel them in terms of (dis)comfort.

    In static, I tend to be able to stand them. Sometimes, I even enjoy them (in the beginning). It’s weird: as if I get a fresh breath of air with each contraction (every 4-5-6 seconds in the beginning). I have done (dry) breathholds with 2+ min. of contractions. I have done 4+ min in static (dry!)

    In dynamic (with fins) however, my PB is ONLY 50m. I keep stopping at 50m, because my contractions start around 30-35 m and get worse very rapidly. Unbearable almost. Maybe I’m swimming too fast, being too tense… (It takes me around 50 sec – 1 min. to do 50m with fins).
    I did do one 50m DYN without contractions, but I have to admit my breathe up involved a bit of hyperventilation. That’s not only cheating, but above and before all: dangerous, I know. Never again, promise!

    So, yes, I’m struggling with contractions as well, especially in DYN. Even though I know it’s not a sign of being really hypoxic… I know all that…

    In short:

    :-/

  4. Christian 24/06/2016 at 7:10 pm - Reply

    I am brand new to the sport, and am curious, and slightly worried, about diaphragm contractions. I can consistently (and comfortably) have breath holds of 2:00-2:30, and I have the occasional breath hold of more, (3:01 being my PB). However, I have not experienced any contractions, or I’ve at least not recognized them as contractions…

    A minute and a half in, my throat usually begins to push air from my lungs back into my mouth in small amounts. For a while I assumed these were contractions, but based on what I’ve read about contractions since then I hesitate to call them that anymore, especially because I can almost completely stop them just by focusing on closing my throat.

    My first thought was that I am hyperventilating, but I don’t think I am because I do the same breath up every time (relaxing with normal breathing for twice as long as my previous breath hold followed by 2/4 or 3/6 breathing for 5-10 breaths followed by 3 large inhales, the third being my final breath before my breath hold).

    Are these actually contractions? If not, should I be experiencing contractions? Is my breath up routine causing me to hyperventilate?

    • Emma Farrell 23/07/2016 at 8:27 pm - Reply

      Hi Christian,

      Without seeing you in person it’s difficult to say exactly whether or not you are hyperventilating, however any more than I large inhale before you go is hyperventilation. Try a different breathing preparation of very gentle abdominal breaths, as if you are falling asleep. Don’t try and make it for any particular count, just zone off. Then take a quick big breath in, a full exhale, a full inhale and start your hold.

      Remember, the O2 saturation of your blood is usually around 99% without you doing anything special with your breathing.

      It is worth mentioning that many people don’t experience contractions at all. I do urge you however to get to a good instructor so they can see what you are doing.

  5. Pote 26/07/2016 at 1:20 pm - Reply

    Hi, it is interesting article. My contraction varies in different disciplines. When they started they never stopped and they are more and more intense.

    STA dry – contractions starts around 2 minutes. They are very very discomfort. My PB is 5:10

    STA wet – contr. starts around 2 minutes. Discomfort but I’m able to relax better and ignore them a little. PB is 5:35

    DNF and DYN – starts around 50 meters. They are there I feel them but don’t disturb too much. I can ignore them easily. PB is 120m.

    CWT and FIM – I have them but I can ignore them easily. But in cold water they start very early around 15m so it often spoils my mouthfill and equalization 🙁

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