We’re taught that oxygen is life. From school biology lessons to fitness trackers, the message is clear: more oxygen equals better health. But over a century ago, Danish biochemist Christian Bohr (father of Nobel Prize–winning physicist Niels Bohr) uncovered a physiological truth that still escapes most people today: carbon dioxide (CO₂), long labeled a waste gas, is essential to using oxygen effectively.
In 1904, Bohr demonstrated that CO₂ is not just tolerated by the body—it’s vital. It allows hemoglobin, the molecule in red blood cells that carries oxygen, to release that oxygen into the tissues. Without enough CO₂, hemoglobin holds onto oxygen too tightly, meaning your blood may be fully oxygenated, but your muscles, brain, and organs stay starved.
This is known as the Bohr Effect, and it changes how we think about breathing. The real issue isn’t always how much oxygen you take in—it’s how well your body can let it go where it’s needed. And CO₂ is the key.
When Breathing More Gives You Less
In a healthy adult at rest, arterial CO₂ pressure (PaCO₂) should sit between 35 and 45 mmHg. But many people today breathe too quickly, too often, and too shallowly—especially through the mouth. This type of breathing, often triggered by stress or anxiety, leads to hypocapnia: a drop in CO₂ levels that directly impairs oxygen delivery to tissues.
A landmark study by Litchfield (1999) showed that even short-term hyperventilation can reduce oxygen delivery to the brain by up to 40%, simply because CO₂ loss causes vasoconstriction—a narrowing of blood vessels.
This has major implications not just for health, but for performance. Many elite athletes have learned to increase their tolerance to CO₂ (45–50 mmHg), enhancing endurance, focus, and recovery. Meanwhile, those who live in a state of chronic stress or dysfunction often experience PaCO₂ below 30 mmHg, even with “normal” breathing—and suffer from symptoms ranging from brain fog and fatigue to cold hands and poor sleep.
Why CO₂ Isn’t the Villain
We often think of breathing as a way to get oxygen in and push carbon dioxide out. But in reality, CO₂ is a critical player in your respiratory efficiency, not just a waste product.
It helps:
- Regulate blood pH
- Maintain blood flow and vessel diameter
- Facilitate oxygen release from hemoglobin
- Support nerve function and calm the nervous system
This means that overbreathing—even if unconscious—can sabotage performance, cognition, and emotional regulation. More air is not always better.
Functional Breathing: The Missing Link
So what does better breathing look like?
It’s not “deep breathing” in the conventional sense. In fact, taking large, frequent breaths can actually lower CO₂ too much.
Functional breathing is:
- Slow
- Nasal
- Diaphragmatic (low into the belly)
- Rhythmic
- Adapted to your activity level
By building tolerance to CO₂ and training your respiratory system to work with the Bohr Effect rather than against it, you allow oxygen to reach your brain, muscles, and organs more efficiently. You recover faster, think more clearly, and perform better under pressure.
Breathing is not just automatic. It’s a skill.
And in many ways, it’s the foundation of all other skills—mental, emotional, and physical.
The Bigger Picture (A Quick Sidebar)
In the cultural and environmental discourse, CO₂ is often demonized (and for good reason when it comes to industrial emissions). But this has led to a one-sided view: that CO₂ is always bad.
The truth is more nuanced. At trace levels, CO₂ is essential for plant life, as it drives photosynthesis and oxygen production. In fact, during the last Ice Age, atmospheric CO₂ levels dropped to ~0.018%, pushing global vegetation to the brink. Most plants cannot survive below 0.020%.
Today’s atmospheric CO₂ is around 0.042%, still a trace amount. It's essential to global ecosystems, just as it is to human physiology. The goal isn’t to eliminate CO₂, but to regulate contextual excess, while respecting its vital role in life.
Final Thought: Less Is Often More
In a world chasing more: more oxygen, more energy, more output,... We often forget the power of restraint.
The question isn’t how much oxygen you breathe.
It’s how well your body can use it.
Reclaiming healthy, efficient breathing isn’t about technique alone—it’s about re-learning how to trust the body’s rhythms and recognizing that CO₂ is not your enemy. It’s your partner in performance, in presence, and in life.
Ref:
- Bohr C., Hasselbalch K., Krogh A. (1904) – The original paper on the Bohr Effect.
Read here (PDF)
- Pathway Medicine – Bohr Effect Summary
https://www.pathwaymedicine.org/bohr-effect
- Litchfield, P. (1999) – “Hyperventilation Syndrome: A Critical Review”
https://www.sciencedirect.com/science/article/pii/S0006899300023210
- Meyer, J.S., Gotoh, F. (1960) – Effects of hyperventilation on EEG and cerebral circulation
https://jamanetwork.com/journals/jamaneurology/fullarticle/562924
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Sperlich, B., & Holmberg, H.C. (2017) – “The Responses of Elite Athletes to Exercise”
https://www.frontiersin.org/articles/10.3389/fphys.2017.00564/full
- Gerhart & Ward (2010) – “Plant responses to low CO₂ during the glacial periods”
https://doi.org/10.1016/j.tree.2010.05.004
- Manitoba Agriculture – CO₂ Supplementation in Greenhouses
https://www.gov.mb.ca/agriculture/crops/crop-management/co2-supplement.html
- OSHA – Permissible Exposure Limits (CO₂)
https://www.osha.gov/annotated-pels/table-z-1
- CCOHS – Carbon Dioxide Chemical Profile
https://www.ccohs.ca/oshanswers/chemicals/chem_profiles/carbon_dioxide.html