The Moment I Realized the Benefits of Full Exhalation
Recently, I experienced the profound benefits of fully exhaling. It’s recommended for good health to exhale completely, and I pondered why that might be.
Previously, I took breathing for granted, only paying attention to it during yoga or Pilates classes. The pandemic made me appreciate the importance of breathing more, but I hadn’t changed my daily breathing habits. Despite knowing it’s beneficial, incorporating it into daily life proved challenging.
The turning point came during a series of cataract surgeries that I performed. Performing 12 surgeries in one afternoon, I noticed my fingertips turning cold around the tenth surgery. I felt a vague sense of fatigue, which I traced back to shallow breathing. The intense focus required for surgery led to my shallow breaths. Taking 2-3 minutes between surgeries to fully exhale made a difference; my fingertips no longer turned cold, and my mind felt clearer.
The Importance of Oxygen and Carbon Dioxide Levels
It goes without saying that our bodies need sufficient oxygen. The air contains about 21% oxygen and 0.04% carbon dioxide. Oxygen levels below 18% can lead to hypoxia, and below 16%, symptoms start to manifest. Below 10%, there’s a risk of death. Conversely, carbon dioxide levels above 3-4% can cause headaches, dizziness, and nausea, and levels above 7% can lead to unconsciousness or even death. These figures show how sensitive our bodies are to the levels of oxygen and carbon dioxide in the air around us.
Are We Using the Air’s Oxygen Efficiently?
Despite the air containing approximately 21% oxygen and 0.04% carbon dioxide, the oxygen concentration in exhaled breath reduces to 16%, while carbon dioxide increases to 4%. Let’s simplify this concept to understand it better: Normally, we breathe in and out about 500mL of air (this is the tidal volume). If we could exhale all the air in our lungs, we would be able to maintain a high oxygen level with each breath. However, in reality, about 2000mL of air remains in the lungs after exhaling. By applying this simplified model, if the residual air has an oxygen level of 16%, then the oxygen concentration after inhaling 500mL of air at 21% oxygen would be (500mL × 21% + 2000mL × 16%) ÷ 2500mL = 17%. This calculation shows that the oxygen level in the lungs significantly drops from the ambient 21%. Similarly, the carbon dioxide level in the lungs, following this model, can be calculated as (500mL × 0.04% + 2000mL × 4%) ÷ 2500mL = 3.2%. This illustrates how the remaining lung volume after normal exhalation significantly impacts the oxygen and carbon dioxide levels in the lungs.
It’s also understandable that when we become overly focused on work and our breathing becomes shallow, the volume of ventilation decreases, the amount of residual air increases, leading to a further decrease in oxygen levels and an increase in carbon dioxide levels in your lung.
ここに過度に仕事に集中して、呼吸が浅くなると、換気量が減り、残存空気量が増加して、酸素濃度のさらなる低下、二酸化炭素の上昇が起きてしまうことも理解できると思う。
Why Does Fully Exhaling Improve Breathing Efficiency?
From the explanation above, it’s evident that reducing the air remaining in the lungs after a normal exhalation can increase the oxygen content with each breath. Typically, after a normal exhalation, a significant amount of air remains in the lungs. This includes the residual volume, which is about 1000mL of air that remains in the lungs and cannot be voluntarily expelled, and the expiratory reserve volume, which is an additional volume of air that can be exhaled beyond the normal exhalation, also approximately 1000mL. By consciously exhaling fully, we can expel the expiratory reserve volume, increasing the oxygen concentration in the lungs. In a simplified model, if we consider the normal tidal volume as 500mL and add the expiratory reserve volume, the total exhalation volume increases to 1500mL. By doing so, the remaining lung volume after exhalation reduces to the residual volume of about 1000mL, thereby increasing the oxygen concentration. With this enhanced exhalation, the oxygen concentration in the lungs can be calculated as (1500mL × 21% + 1000mL × 16%) ÷ 2500mL = 19%. Similarly, the level of carbon dioxide in the lungs also decreases, calculated as (1500mL × 0.04% + 1000mL × 4%) ÷ 2500mL, which equals approximately 1.6%. This method effectively increases the oxygen concentration in the lungs and significantly reduces the carbon dioxide levels.
Comparing Fully Exhaled Breathing with Full Inhalation and Deep Breathing
What happens if we fully inhale? The spare capacity for inhalation, known as the inspiratory reserve volume, is about 3000mL. When combined with the normal tidal volume of 500mL, the total inhalation volume can reach up to 3500mL. Considering this, the oxygen and carbon dioxide levels with full inhalation can be calculated as follows: The oxygen level is (3500mL × 21% + 2000mL × 16%) ÷ 5500mL ≈ 19.2%, and the carbon dioxide level is (3500mL × 0.04% + 2000mL × 4%) ÷ 5500mL ≈ 1.5%. Thus, full inhalation generates similar oxygen and carbon dioxide levels as full exhalation. However, fully exhaling involves ventilating only 1500mL, compared to the 3500mL ventilated with full inhalation. This shows that fully exhaling is more than twice as efficient as fully inhaling.
What about combining full exhalation with full inhalation, i.e., deep breathing? When we perform deep breathing, we use both the expiratory reserve volume and the inspiratory reserve volume, maximizing the ventilation capacity. This process brings the oxygen and carbon dioxide levels in the lungs much closer to those in the ambient air. For example, when the total ventilation capacity reaches its maximum (say, 4500mL with deep breathing) and the remaining lung volume after deep breathing is minimal (approximately 1000mL), the oxygen level can be calculated as (4500mL × 21% + 1000mL × 16%) ÷ 5500mL ≈ 20%, and the carbon dioxide level as (4500mL × 0.04% + 1000mL × 4%) ÷ 5500mL ≈ 0.76%. Deep breathing thus maximizes the oxygen level in the lungs, closely approximating the ambient air oxygen level.
How Should We Breathe at Work?
The Noticeable Actions of Deep Breathing and Full Inhalation
How can we apply what we’ve learned about breathing to our daily lives? First, we understand that deep breathing is the most efficient in terms of respiratory effectiveness. However, its application is limited. Deep breathing involves inhaling and exhaling up to 4500mL of air, which can cause noticeable movements of the chest and, depending on the method, audible breathing. Deep breathing, with its significant physical actions, can be conspicuous. It might not seem unusual when done at home in the morning, while driving, at the start of work, during breaks, at lunch, or after returning home. However, deep breathing at work might raise eyebrows. For instance, if I were to deep breathe frequently during cataract surgery, both the patient and the assisting nurse might worry that something has gone wrong.
Interestingly, full inhalation, which involves inhaling and exhaling as much as 3500mL, also results in significant physical actions, similar to deep breathing.
The Subtle Nature of Full Exhalation
In contrast, fully exhaling involves only 1500mL and brings minimal changes, mainly involving the contraction of the abdomen. This subtlety makes it less noticeable to others and avoids causing unnecessary concern. With practice, it can be done while walking or working. If you notice shallow breathing during work, why not try fully exhaling? When you do, you expel the stale air and allow fresh air with an oxygen concentration of 21% to fill your lungs. You might feel the refreshing sensation of high-oxygen air spreading throughout your lungs.