Freediving training

CO² and O² training: your path to improving breath-holding

Freediving is not just a physical, but also a psychological challenge. It's the art of training the body to function under conditions of oxygen deficiency and carbon dioxide excess, allowing freedivers to spend significant amounts of time underwater. This process requires the development of specific skills and adaptations, including increasing breath-holding time and adapting the body to hypoxia (low oxygen levels) and hypercapnia (high carbon dioxide levels). CO² and O² training serve as key tools for achieving these goals.

CO² and O² Tables: what are they?

CO² and O² tables are specialized training programs designed to enhance the body's adaptations to low oxygen (O²) levels and high carbon dioxide (CO²) levels. They aim to improve breath-holding ability and overall body endurance, and also contribute to a better understanding of one's body and its response to various stresses.

CO² tables aim to increase the level of carbon dioxide in the body, training you to be comfortable even at high CO² concentrations. This is achieved by reducing the recovery period between breath-holds, which increases the CO² concentration in the blood and teaches the body to cope with this condition without panic or discomfort.

On the other hand, O² tables focus on training the body to work with minimal oxygen. They teach the body to be more efficient in using available oxygen reserves, increase the level of aerobic endurance, and allow for a deeper understanding of one's body and its limits.

How are tables constructed?

The basis for constructing these tables usually takes half the time from the athlete's maximum breath-hold. For example, if your record is 2 minutes, half of this time is taken to create the tables. Therefore, in the CO² table, the breath-hold will be 1 minute. This approach allows training participants to work within their comfort zone, gradually increasing the intensity of workouts and developing the body's ability to adapt to changing conditions.

Examples of CO² and O² training tables

CO² table

In the CO² table, the breath-hold time remains constant, while the recovery time decreases after each cycle. Here is an example of a CO² table for a person whose maximum breath-hold is 2 minutes:

  1. Cycle: 1 minute breath-hold, 1 minute 30 seconds rest.
  2. Cycle: 1 minute breath-hold, 1 minute 20 seconds rest.
  3. Cycle: 1 minute breath-hold, 1 minute 10 seconds rest.
  4. Cycle: 1 minute breath-hold, 1 minute rest.
  5. Cycle: 1 minute breath-hold, 50 seconds rest.
  6. Cycle: 1 minute breath-hold, 40 seconds rest.
  7. Cycle: 1 minute breath-hold, 30 seconds rest.
  8. Cycle: 1 minute breath-hold, 20 seconds rest.

O² table

In the O² table, the recovery time remains constant, while the breath-hold time increases after each cycle. Here is an example of an O² table for the same person:

  1. Cycle: 1 minute breath-hold, 2 minutes rest.
  2. Cycle: 1 minute 10 seconds breath-hold, 2 minutes rest.
  3. Cycle: 1 minute 20 seconds breath-hold, 2 minutes rest.
  4. Cycle: 1 minute 30 seconds breath-hold, 2 minutes rest.
  5. Cycle: 1 minute 40 seconds breath-hold, 2 minutes rest.
  6. Cycle: 1 minute 50 seconds breath-hold, 2 minutes rest.
  7. Cycle: 2 minutes breath-hold, 2 minutes rest.
  8. Cycle: 2 minutes 10 seconds breath-hold, 2 minutes rest.
Please note that these tables are examples and can be adapted according to your individual abilities and goals. It is important to conduct such training under the supervision of an experienced instructor to ensure the safety and effectiveness of the training process.

Understanding the importance of CO² and O²

Carbon dioxide (CO²) and oxygen (O²) play a vital role in human physiology. CO², which is the end product of metabolic processes, is typically expelled from the body through the respiratory system. On the other hand, O² is consumed by our cells to maintain metabolic activity and generate energy.

In the context of freediving or breath-holding, these gases become even more critical. During breath-holding, the levels of O² in the body drop as it is utilized by the cells, and the levels of CO² rise as it continues to accumulate. This triggers a series of physiological responses, which may include increased breathing, a sensation of needing to breathe, and others. Training with CO² and O² tables helps the body adapt to these changes, which ultimately improves your breath-holding capability.

Benefit of training with CO² and O² tables

Training with CO² and O² tables brings several benefits, which can be divided into three main categories:

  • Increasing breath-hold duration: Regular training will help you improve your overall breath-holding ability. This is especially useful for freedivers, for whom the duration of breath-hold can be a critical factor for success.
  • Improving comfort during breath-holding: Gradual adaptation to high levels of CO² and low levels of O² can reduce the discomfort usually associated with breath-holding. This makes the process more comfortable and less stressful.
  • Strengthening confidence in your underwater abilities: Knowing that your body is capable of adapting to conditions of hypoxia (low oxygen levels) and hypercapnia (high carbon dioxide levels) will make you feel more confident and safe when diving.

Developing an individual training plan

For optimal effectiveness of training with CO² and O² tables, it is important to approach them consciously and individually. This might mean starting with standard tables, but over time, as you gain more experience and your body adapts, it is important to tailor these tables to your specific needs. This could include modifying the breath-hold time, rest time between attempts, or overall number of repetitions. Remember, your plan should be evolving and adapt to your current capabilities and goals.

The importance of safety

Safety is an absolutely critical aspect when conducting CO² and O² table training, especially when practicing freediving. Remember that any training in the water should only be conducted in the presence of a partner or instructor who can provide immediate assistance if necessary. This is vital as the risk of hypoxia and loss of consciousness increases significantly when diving.

On the other hand, "dry" training sessions, which can be done out of the water (for example, lying on a bed), can be done alone. But even in such cases, it is important to be aware of your physical sensations and not exceed your limits.

Utilizing modern technologies

Modern technologies, including mobile applications, can be very useful for facilitating CO² and O² table training. They can offer various tables, timers, and other functions that will help you track your progress and simplify the training process.

One of the best apps for such training is the Freediving Trainer (also known as Apnea Trainer), the icon of which is a handprint. It offers a range of features including various training tables, time settings, and progress tracking. All this makes it a great tool for freedivers of all levels.


CO² and O² table training is an important part of freediving preparation. They help improve your breath-holding ability, adapt your body to hypoxic and hypercapnic conditions, and increase your comfort and confidence underwater.

It's important to underline that effective training requires an individual approach and professional guidance. This will help you achieve your goals safely and effectively, despite the fact that the training can be intense and require a lot of physical and psychological effort.

At our Apnetica Freediving diving school, we value each student and strive to provide personally tailored training that meets your unique needs and goals. Our experienced instructors are always ready to help you in composing tables and training in water. We provide a safe and supportive environment for learning and practicing freediving, regardless of your level of experience.

Remember, safety is a key aspect when performing CO² and O² table training, especially when practicing freediving. Always listen to your body and don't exceed your limits.

Finally, don't forget that modern technologies can be your allies on the path to success in freediving. Use them to track your progress and make training more convenient.

With the right preparation, patience, and support from our team, you can significantly improve your freediving abilities. We at Apnetica Freediving are always here to help you on this journey!

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