Why do you get contractions?

The rising levels of CO2 in your blood and tissues during a breath hold is a main trigger in sending signals to your brain and subsequently the body’s breathing muscles to start breathing.

But there are more factors involved. It is very difficult and costly to research what exactly happens in our bodies when emerged in water and especially when diving deep.

Most advise given by freedivers on how to deal with contractions and what triggers them is based on personal experiences, not science based data.

Personally I get contractions sometimes very early in a dive and sometimes almost none. Sometimes I get contractions on my way down very early in a dive.

Why do you sometimes get contractions of the breathing muscles when just starting a dive? Your CO2 levels are most likely still normal, so it cannot just be the CO2. 

Listening today to The Freedive Cafe podcast Episode #152  shed some more light on this topic. 

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An interesting point of view is that it is basically always the brain that communicates the desire to breathe.

It therefore could also be an association or a memory that is triggering this urge to breathe. It does not always have to be a physiological factor. 

Perhaps you are not comfortable at the start of the dive. You are telling your body to hold your breath but your brain at the same time is like “hey what is happening here?”

Especially when we dive vertically and have pressure involved there are many things happening in our body and brain. Rising CO2 levels, lower O2, high nitrogen on deep dives. Changing partial pressure, blood shift, bradycardia (slower heart rate) etc. etc. 

An interesting view presented in the podcast is that potentially even the stretching (when inhaling before a dive) and compression of the lungs due to the pressure changes could cause contractions. The pulmonary stretch receptors in the longues could play a role in communicating to your brain the urge to breathe. 

The pressure change at the beginning of the dive is the greatest and might therefore trigger the contractions early in a dive. When you start with very inflated lungs this pressure change might even be more triggering.

So perhaps packing your lungs with too much air might actually trigger the contractions earlier.

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In my opinion the most important thing to do before a dive is to send a signal to your body and brain that everything is fine. 

Therefore during courses I teach to breathe light and slow, definitely not hyperventilating. Your slow breathing will send a signal to your brain and body that all is fine and you can relax. 

Long story short, it is not just CO2 playing a role here. As always it is your mental approach, relaxation and breathing.

True learning happens when the mind and body are rested and quiet. True relaxed diving only happens when the mind and body are rested and quiet.

My view is here that relaxation again is key to a successful dive. You want to be in a relaxed state of mind (and body) before your dive. Your mind and body need to know that everything is A OK!

CO2 of course still plays a major role and luckily we can train to become more tolerant of higher CO2 levels. 

CO2 tolerance can be trained by diving frequently but when you are not diving on a regular basis you can also easily implement a daily routine of regular small breath holds to get used to higher CO2 levels. These small breath holds you can even do when sitting behind your desk or walking to the store. 

If you want more tips on how to work on your CO2 tolerance send me an email and we can have a talk to see what suits you best and what fits your schedule and lifestyle.