Contractions in freediving

Contractions in freediving: understanding and management

Freediving is not only a sport that requires physical preparation and technical skills but also the art of a deep understanding of one's body functioning. One of the key aspects of freediving practice is the contractions of the diaphragm, which play an important role in breath-holding.

What are contractions?

Contractions are involuntary muscle contractions related to breathing, especially of the diaphragm, which occur as the body's response to the increasing level of carbon dioxide (CO²) in the blood during breath-holding. These muscle contractions can be felt as discomfort, burning, or even unpleasant pressure in the chest and throat area.

Causes of contractions

During normal breathing, the human body constantly maintains a certain level of gases in the blood, particularly oxygen (O²) and carbon dioxide (CO²). Oxygen is necessary for cellular metabolism and energy production, while carbon dioxide is a byproduct of these processes and must be expelled from the body.

When you hold your breath, cellular oxygen consumption continues, the level of oxygen in the blood gradually decreases since the intake of O² stops. At the same time, the production of CO² continues to accumulate as its expulsion is disrupted due to the lack of lung ventilation. This accumulation of CO² leads to a shift in the blood's acid-base balance towards acidity, i.e., respiratory acidosis.

The body detects changes in the gas composition and pH of the blood through specialized chemoreceptors. Central chemoreceptors, located in the brain, respond to changes in CO² levels and blood pH. When these receptors detect high levels of CO², they send signals to the brain's respiratory center, which in turn stimulates reflex motor responses – contractions of the diaphragm and other respiratory muscles. These contractions, also known as breath-hold spasms or spasms, are the body's attempt to resume breathing and restore normal gas exchange.

Contractions can be felt as involuntary contractions of the abdominal muscles or thoracic cavity and are a sign that the body requires resuming breathing to correct blood gas levels. For freedivers, contractions are an indicator of the limit of their breath-holding ability, and it is important to learn to recognize these signals and respond to them appropriately to avoid the danger of hypoxia and loss of consciousness underwater.

Managing contractions

The most effective way to manage contractions is relaxation. Reducing physical tension allows contractions to proceed more smoothly and with less discomfort. Relaxation techniques and attention focusing are used by many freedivers to reduce the frequency of contractions and the time of their onset.

Mastering the skills to keep a calm mind during diaphragm muscle contractions will make the contractions more comfortable and increase the time between them and, consequently, the overall breath-holding time. However, the principle of gradualness and caution when increasing loads remains paramount.

To safely expand your abilities in freediving, it is extremely important to deeply understand the mechanisms of your body's functioning, including the nature and causes of diaphragm contractions. Regular training will help better feel the individual characteristics of contractions and learn to recognize the approach of dangerous limits.

Ensuring safety during contractions

It's essential to remember that although contractions are a normal part of the breath-hold process, they also signal the approach of the body's limits. There is a high risk of losing consciousness (blackout) amidst numerous contractions, so it's crucial not to push oneself to a critical state. When practicing apnea in water, a trained partner should always be nearby, ready to provide assistance.

Safety Recommendations

  • Gradually increase breath-hold durations
  • Carefully analyze how you feel after each attempt
  • Stop training if unusual or worrying symptoms appear
  • Avoid breath-holding alone without a safety backup

You can read more about how to train properly in static breath-hold in the article "Static apnea (STA): tips for safety and efficiency".

Individual perception of contractions

For some freedivers, contractions can be relatively painful and difficult to manage, while others describe them as less intense and easily controllable. The time interval between contractions can also vary greatly, from a few seconds to 10 seconds or more between contractions. Trained athletes during static breath-hold are capable of withstanding up to a hundred contractions while remaining conscious.


Diaphragm contractions during breath-holding are an important indicator of the body's condition, and understanding and managing them is necessary for safety and progress in freediving. Gradually expanding the limits of your capabilities, respecting the signals of the body, and strictly adhering to safety rules will minimize risks.

Contractions are like a beacon indicating the approach of danger. But if managed correctly, they can become a reliable guide on the path to new achievements. They will help you better understand yourself and control your body in extreme hypoxic conditions. This invaluable experience is useful not only in freediving but also in everyday life.

At our school, Apnetica Freediving, we pay great attention to physiology and safety issues. In our freediving courses, we share knowledge about the mechanisms of contractions and teach skills to control them. Our goal is not only to develop the professionalism of our students but also to cultivate their mindfulness and attention to their own bodies. Come to us for knowledge that will allow you to safely reach new heights!

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