CO2 tolerance and contractions

In March 2021, when my coach presented the main lines of the training program that awaited us, I must admit that seeing the “CO2” component appearing did not please me. I like freediving, but I do not want to suffer and even less to have contractions (spasms), it was out of the question for me purposely expose myself to this unpleasant sensation too frequently.

The mistake I made back then was to believe that being tolerant to CO2 meant being able to tolerate and endure the contractions caused by its increase… This is a common mistake in freediving that we will try to debunk here.

Let’s get outside of the freediving frame:

Let’s imagine that you have a lactose-intolerant friend who, when he drinks milk, has nausea and uncontrollable spasms.

Then, imagine that this friend explains to you that he wishes to increase his tolerance to lactose. He explains to you that he regularly forces himself to drink several glasses of milk and that thanks to this regular practice, he is more and more comfortable with nausea and spasms induced by lactose ingestion.

I hope we agree to say that this situation is absurd!

If the goal is to improve lactose tolerance, the result must be the ABSENCE of spasms and nausea when ingesting milk.

To return to apnea.

When we have a contraction, our body expresses a rejection. We tend to minimize a contraction but let’s be clear, it doesn’t matter if it’s a “small” one or if we manage to stay calm in its presence, it is anyway an uncontrolled movement of your body, an alert of your nervous system that something is wrong. You are no longer in control of yourself (and let’s be honest, we are not talking about an orgasm !). Being able to get used to it can certainly allow you to get a short-term result, but it is not a sustainable way to progress for most of us!

Freediving training

Generally speaking, the purpose of freediving training should be neurological desensitization to the stimulation that will be induced by your goal (CO2 in this case, but there are obviously other components in a performance). It is the very principle of adaptation. Once the training phase is over, we can enter a performance phase (much shorter) during which, if you wish (but it is not a requirement with a good periodization and a long term vision of your training) you will be able to sacrifice a little bit the quality of your dives to get a result. Nevertheless, these “performance” dives can only constitute a small fraction of your dives at the end of your training cycle.

How to improve your CO2 tolerance in freediving?

If you want to increase your CO2 tolerance, the first thing to do is eliminate stress-related contractions. I recommend that you repeat dives at 50% of your maximum with complete recovery until you consistently have zero contractions. 

Then you must build your training to try to expose yourself as often as possible to the period that PRECEDES the arrival of a contraction while remaining in perfect control and mastery of yourself:

If it is truly CO2-related, a contraction does not come on its own; you should feel heat and tightness in the chest before it arrives. This “pre contraction” feeling is the ideal training zone to increase CO2 tolerance. While in this zone, keep your composure and focus: use them to ensure that the dive experience remains positive. By injecting a small dose of CO2 (stimulation) into a general comfort level, you will be able to progressively reprogram your nervous system and delay the uncontrolled response to an increased CO2 (contraction).

Conclusion :

I hope this article has given you the tools to think about your training better. Wanting to learn to “suck it” to progress may seem tempting for some, but as in all sports, this mentality is mostly proof of impatience associated with intellectual laziness. It will only limit you from realizing your potential. The difference between freediving and other sports is that it is difficult to get badly injured in freediving. Therefore, it is possible to be in permanent over-training: Mood swings, irritability, squeeze, equalization issues, insufficient sleep, anxiety before a session, lack of motivation for training… Take care of yourself and do not ignore those signs; your training is probably too intense.