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The Top 3 Reasons to Train CO2 Instead of Oxygen in Breath Training

Breathing is something we do 20,000 to 25,000 times a day without thinking. But what if the way we’ve been taught to breathe is actually working against us?

In the world of breath training, oxygen tends to steal the spotlight—inhale deeply, expand your lungs, fuel your body. But the real key to optimizing breathing, performance, and even stress management isn’t about sucking in more air.

It’s about training your CO2 tolerance.

CO2, or carbon dioxide, has long been misunderstood as just a waste gas. The reality? It’s the hidden hero of your respiratory system. If you want to breathe better, move better, and feel better, it’s time to shift your focus.

Here are the top three reasons to train CO2 instead of focusing on oxygen intake in your breath training.

“We don’t rise to our level of training; we fall to the level of our breathing efficiency.”

1. CO2 Is the Key to Oxygen Utilization

Most people think oxygen is what fuels our muscles, brain, and nervous system. That’s only half the story.

Oxygen doesn’t just magically enter your cells and power them—it has to be released from hemoglobin in the bloodstream first.

And guess what triggers that release? CO2.

This process, called the Bohr Effect, explains why high CO2 tolerance equals better oxygen delivery:

• When CO2 levels increase, the blood becomes slightly more acidic, prompting hemoglobin to release oxygen where it’s needed.
• If you constantly breathe in excess oxygen and hyperventilate, CO2 levels drop, and your body actually holds onto oxygen instead of using it efficiently.
• Without enough CO2, your cells can’t get the oxygen they need, leading to symptoms like brain fog, fatigue, muscle cramps, and dizziness.
   

“More oxygen doesn’t mean better breathing. More CO2 tolerance does.”

This is why elite athletes, freedivers, and high-performance individuals train CO2 tolerance instead of just focusing on big inhales. They understand that better oxygen delivery happens not by breathing more, but by breathing better.

2. CO2 Training Reduces Stress and Enhances Nervous System Regulation

The way you breathe directly affects your nervous system. Rapid, shallow breathing (often caused by low CO2 tolerance) keeps your sympathetic nervous system (fight or flight) in overdrive. This can lead to:

•  Chronic stress
•  Increased anxiety
•  Poor sleep
•  High blood pressure

On the flip side, training CO2 tolerance helps activate the parasympathetic nervous system (rest and digest), bringing your body back into balance. Here’s how:

•  Slower breathing patterns signal safety to the brain.
•  Increased CO2 calms neural activity, reducing overactive stress responses.
•  Exhalation-focused breathing enhances vagus nerve function, which helps regulate heart rate and emotions.

“The breath is the bridge between the brain and the nervous system.”

Many people who suffer from panic attacks or chronic stress are actually overbreathing, unknowingly lowering their CO2 levels and triggering their own anxiety cycles.

By training CO2 tolerance, you can break this loop and shift your body into a calm, controlled state.

3. CO2 Training Improves Athletic Performance and Endurance

Want more endurance, better recovery, and increased physical performance? Forget gulping air. Start training your CO2 tolerance.

Here’s why CO2 is critical for athletic performance:

• Higher CO2 tolerance means less breathlessness. Many people feel winded not because they lack oxygen, but because their body isn’t adapted to higher CO2 levels.
• Increased CO2 enhances oxygen efficiency, so your muscles get more fuel with fewer breaths.
• It boosts cardiovascular function, improving heart rate variability (HRV) and overall stamina.

“Endurance isn’t about how much oxygen you take in—it’s about how well your body uses it.”

Final Thoughts: Train Smarter, Not Harder

If you’re serious about breathing better, improving performance, and reducing stress, the answer isn’t in more oxygen—it’s in training your CO2 tolerance.

By focusing on:

1.  Improving oxygen utilization
2.  Enhancing Nervous System Regulation
3.  Boosting endurance and performance

…you’ll experience transformational benefits in your health, fitness, and overall well-being.

“Breathe less. Perform more.”

Ready to take your breath training to the next level? Learn how to assess and train CO2 tolerance with proven neuro-based breathing techniques in the Next Level Neuro Fundamentals Course.

This course is designed for coaches, trainers, and individuals who want a practical, neuroscience-backed approach to breath training.

You’ll learn:

•  How to assess and fix breathing dysfunction
•  CO2 tolerance drills for better nervous system regulation
•  Proven techniques to boost endurance and reduce stress

Start training the right way. Join the Fundamentals Course today!

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