When working with new groups, I often ask participants what they notice about their breath. A common response is that they hold their breath and tighten up their muscles when stressed. This seems to contradict what we teach about the benefits of breath holds to build tolerance to CO2. The truth is, the implications of breath-holding depend significantly on the manner and purpose of the breath-hold.

Stress and Involuntary Breath-Holding

When people say they hold their breath due to stress, it typically refers to an involuntary response to anxiety or tension. This type of breath-holding is usually brief and irregular, occurring in response to acute stressors. It is often associated with shallow breathing or hyperventilation, which can lead to a cascade of negative effects:

  • Reduced Oxygen Intake into the Lungs: Involuntary breath-holding can lead to a decrease in the amount of oxygen taken into the lungs.
  • Lower Blood Oxygen Levels: With less oxygen entering the lungs, the bloodstream has less oxygen to transport to the cells.
  • Impact at the Cellular Level: Consequently, tissues and organs may not receive sufficient oxygen, exacerbating feelings of anxiety, muscle tension, and overall discomfort.
  • Compensatory Hyperventilation: Following a period of breath-holding, individuals often overcompensate by breathing rapidly and shallowly. This hyperventilation is an attempt to quickly rebalance oxygen and carbon dioxide levels.
  • Negative Feedback Loop: Hyperventilation lowers carbon dioxide levels too much (hypocapnia), leading to symptoms like dizziness and tingling. These symptoms can increase anxiety, perpetuating the cycle of stress, breath-holding, and hyperventilation.

In summary, involuntary breath-holding as a response to stress can disrupt normal respiratory function and create a negative feedback loop that heightens anxiety and reduces overall well-being.

Controlled Breath-Holding in Breathwork

In contrast, controlled breath-holding as part of structured breathwork practices can be highly beneficial for health. These practices are deliberate, mindful, and designed to enhance physiological function. Here are some of the benefits and mechanisms:

  • Increased CO2 Tolerance: Controlled breath-holding helps the body adapt to higher levels of CO2, improving respiratory efficiency and reducing sensitivity to CO2, which decreases the likelihood of hyperventilation.
  • Activation of the Parasympathetic Nervous System: Deliberate breath-holding, especially when combined with slow and controlled breathing techniques, can activate the parasympathetic nervous system, promoting relaxation and reducing stress.
  • Enhanced Oxygen Utilisation: Breath-holding can improve the body’s ability to utilise oxygen more efficiently. During a short breath-hold, although the oxygen saturation (SpO2) in the blood may decrease, the increased levels of carbon dioxide trigger the Bohr effect[1]. This physiological response causes haemoglobin to release more oxygen to the cells. Therefore, even though overall oxygen levels in the blood might be lower, the Bohr effect ensures that oxygen delivery to the tissues is enhanced, improving cellular function and efficiency.
  • Respiratory Retraining: Regular practice of controlled breath-holding retrains the body’s response to CO2, helping to develop a more efficient breathing pattern over time.

By integrating controlled breath-holding into breathwork routines, individuals can experience these physiological benefits, leading to improved respiratory health and overall well-being.


Balancing Breath-Holding Practices

Understanding the context and purpose of breath-holding is key to balancing its benefits and potential drawbacks. Here are some considerations:

  • Awareness and Mindfulness: Controlled breath-holding should always be practiced mindfully and with full awareness of one’s physical and mental state. This ensures that the practice is beneficial rather than stressful.
  • Guidance from Professionals: For those new to breathwork, guidance from a certified instructor can help ensure that techniques are performed correctly and safely, maximising benefits and minimising risks.
  • Integration with Overall Health Practices: Breath-holding techniques should be integrated with other health practices such as regular exercise, a balanced diet, and stress management strategies for holistic well-being.
  • Regular Practice and Monitoring: Consistent practice of controlled breath-holding, along with monitoring progress through measures like the BOLT score (see below), can help track improvements in CO2 tolerance and respiratory efficiency.
  • Non-Competitive Approach: It’s important to approach breath-holding exercises as a personal practice rather than a competitive one. The goal is to gradually improve breathing efficiency and overall health in a calm and controlled manner.

By considering these factors, individuals can effectively balance the benefits of controlled breath-holding with their overall health and wellness routines.


Practical Advice

  1. Identify stress-induced breath-holding: Become aware of moments when you might be holding your breath due to stress. Practise consciously releasing this tension by taking light, slow, deep (low) breaths.
  2. Incorporate breathwork into daily routine: Schedule regular breathwork sessions that include controlled breath-holding to train your respiratory system and enhance relaxation.
  3. Listen to your body: Pay attention to how your body responds to different breathwork techniques. Adjust practices as needed to ensure they are comfortable and beneficial.

In summary, while involuntary breath-holding due to stress can have negative effects, controlled breath-holding as part of structured breathwork can provide significant health benefits. The key lies in the intentionality and method of the practice.

[1] The Bohr effect, discovered by Christian Bohr, describes how elevated carbon dioxide levels reduce blood pH, thereby decreasing haemoglobin’s affinity for oxygen. This allows for more oxygen to be released to the tissues where it is most needed, especially during physical activity or stress-induced breath-holding. This mechanism supports the idea that controlled breath-holding can enhance oxygen delivery and utilisation even under conditions of reduced blood oxygen levels​.


Your BOLT Score

Here’s a straightforward Oxygen Advantage® field protocol for measuring your current tolerance to CO2. This method is designed to assess how well your body tolerates and utilises CO2, which is an important factor in respiratory efficiency and overall health.

1. Prepare yourself:

  • Sit down comfortably in a chair with a tall spine and both feet on the floor.
  • Take a few moments to relax and breathe normally through your nose.

2. Breathe normally:

  • Take a calm, normal breath in through your nose.
  • Exhale normally through your nose.

3. Pause the breath:

  • After a normal exhalation, pause the breath (you may like to gently pinch your nose with your fingers). Start the stopwatch.
  • Control the pause until you feel the first definite desire to breathe, such as a slight twitch in your diaphragm or a change in your breathing muscles. This should be a comfortable pause, not forced or strained.

4. Release and breathe normally:

  • When you feel this first definite desire to breathe, resume normal, calm breathing through your nose. Note the time on the stopwatch.

5. Record the time:

  • The time measured from the start of the pause to the first definite desire to breathe is your BOLT score.

Interpretations and Guidelines

20 seconds or less: Indicates a lower CO2 tolerance and potential breathing inefficiency. This suggests that breathing retraining exercises may be beneficial.

20-40 seconds: Reflects average CO2 tolerance and moderate breathing efficiency. Continued practice and breathing exercises can lead to improvement.

40 seconds or more: Shows good CO2 tolerance and efficient breathing patterns, often associated with better respiratory health and physical performance.

Important Considerations:

Set a baseline:

  •  To establish a reliable baseline, perform the BOLT test at the same time each day under similar conditions. Ensure you are relaxed and in a similar state of rest each time.
  •  Avoid testing immediately after eating, drinking caffeine, or intense physical activity, as these can affect your BOLT score.

Monitor Deviations:

  • Regularly track your BOLT score to monitor deviations from your baseline. Significant changes may indicate variations in your general readiness, stress levels, or respiratory health.

Use in conjunction with other measures:

  • Combine your BOLT score with other health metrics such as resting heart rate (RHR) and heart rate variability (HRV) for a more comprehensive view of your physiological state.
  • Consider using the Shift Network’s CO2 tolerance test, which involves taking a full breath and exhaling slowly through the nose, to further assess your respiratory efficiency and CO2 tolerance.

Individual variation:

  • Understand that these numbers are rough guidelines. Everyone is different, and numerous factors, both internal (like stress levels and health conditions) and external (such as environmental conditions), can influence your comfortable pause.

Non-competitive approach:

  • This test is not a competition. The goal is to understand and improve your breathing efficiency over time in a calm and controlled manner.

Safety first:

  • Always prioritise comfort and safety. If you feel dizzy or uncomfortable at any point, release the breath pause and resume normal breathing.

By regularly practising and tracking your BOLT score, and considering other physiological indicators, you can gain valuable insights into your CO2 tolerance, respiratory health, and overall well-being.