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.