CO₂: The ‘Waste’ Gas That’s Not Wasteful At All
→ It’s Actually Fuel for More Endurance
By Anthony Lorubbio, founder and head coach at Recal
Carbon dioxide is often misunderstood. When most people think of carbon dioxide (CO₂), they may picture pollution, a gas we need to exhale, or something that makes us feel out of breath. (That last one only if they have a good understanding of breathing!)
But here’s the truth: CO₂ isn’t just some useless byproduct of breathing—it’s an essential player in how our bodies function at rest, during exercise, and at its peak performance. In fact, CO₂ might just be your secret weapon for better endurance, improved altitude performance, and high-altitude breathing efficiency.
As your friendly neighborhood breathwork coach, I see this misconception all the time. People assume the feeling of breathlessness on a climb is due to a lack of oxygen. But in reality, your ability to tolerate CO₂ plays just as—if not more—significant of a role than the amount of oxygen in the air around you.
Let’s break this down and explore three key reasons why CO₂ is not the enemy, but a critical part of the endurance and altitude performance equation.
1. CO₂ is a Vasodilator—Meaning It Opens Up Your Blood Vessels
One of CO₂’s superpowers is its ability to open up your blood vessels, a process called vasodilation. This means that instead of restricting blood flow, CO₂ actually helps your blood circulate more effectively, ensuring that oxygen-rich blood reaches your muscles, brain, and organs more efficiently—especially in hypoxic (low-oxygen) conditions, which directly impact altitude performance at high elevations. It also plays a significant role in regulating cerebral blood flow.
When you’re on an expedition, every ounce of oxygen matters. But if your blood vessels are constricted due to low CO₂ levels (which happens when you hyperventilate, or simply over-breathe due to the feeling of breathlessness), that oxygen won’t be delivered where it’s needed most. This is why a good Carbon Dioxide tolerance is so crucial in endurance training—learning to regulate your CO₂ levels allows your body to optimize blood flow, including cerebral, and oxygen delivery, making high-altitude efforts feel less exhausting.
2. CO₂ Helps You Use Oxygen More Efficiently (The Bohr Effect)
Breathing in oxygen is one thing. Actually using it effectively is another. That’s where the Bohr Effect comes in. This physiological mechanism explains how CO₂ plays a direct role in oxygen delivery.
Here’s how it works:
When CO₂ levels rise, it lowers the pH of your blood, which reduces the affinity (or ‘stickiness’) between hemoglobin and oxygen. This means that oxygen molecules are more easily released from the hemoglobin (in your red blood cells) and delivered to the muscle tissue or organs that need them most. In other words, your ability to tolerate higher CO₂ levels in your blood makes oxygen more usable, improving altitude performance—and that’s exactly what you want when you’re grinding up a steep incline at 18,000 feet.
3. CO₂ Keeps You Alive—Literally
Now, this one might sound dramatic, but it’s true. CO₂ is the primary driver of your urge to breathe—not oxygen.
Most people assume that feeling breathless means they’re low on oxygen, but in reality, it’s your body reacting to rising CO₂ levels.
Your chemoreceptors (specialized sensors in your body) constantly monitor the pH of your blood. At homeostasis—aka the place your body likes to be—this pH is around 7.35-7.45.
If CO₂ concentrations rise or fall, they influence that pH (high CO₂ levels = a decrease in pH; low CO₂ levels = higher pH). This is where your chemoreceptors step in to signal that it’s time to exhale (if pH moves to the low end of homeostasis) or hold your breath longer (if pH moves to the high end of homeostasis).
Without CO₂, there would be no need to trigger this response, and we wouldn’t even feel the need to breathe—which would obviously be a problem.
If CO₂ didn’t exist, there would be no need to trigger this response, and we wouldn’t even feel the need to breathe—and that’s obviously a problem.
Understanding this is key for overall altitude performance. The stronger your CO₂ tolerance, the better you can control your breathing and resist the urge to over-breathe (which leads to poor oxygenation, inefficient energy use, and something called respiratory alkalosis). This is exactly why we assess your CO₂ tolerance through assessments like the BOLT score, the CO2 Tolerance Test (CO2TT), and the Maximum Breathlessness Test (MBT). And then why we also TRAIN your CO2 tolerance with exercises like Breathe Light and High Altitude Simulation. The assessments help gauge how well you handle CO₂ buildup and provide a benchmark for improving your endurance, while the exercises train for a better CO₂ tolerance.
How to Train CO₂ Tolerance for Better Endurance
If you’re preparing for an expedition, mountain race, or any endurance challenge, training your body to tolerate higher CO₂ levels should be a core part of your routine for peak altitude performance. Here are a few exercises I recommend:
- Breathe Light Exercise: This simple drill involves slowing down your breathing to create mild air hunger, which helps condition your chemoreceptors to tolerate higher CO₂ levels. Try breathing so lightly that you barely feel air moving in and out of your nose for 3-5 minutes a day.
- Nasal Breathing During Workouts: Keep your mouth shut while training and breathe only through your nose. This increases CO₂ tolerance and helps regulate oxygen delivery more efficiently.
If you haven’t tested your CO₂ tolerance before, I encourage you to give it a shot. Try one of these exercises and see how it impacts your training. The more you work on your CO₂ adaptation, the better prepared you’ll be for the altitude demands of your next adventure.
Final Thoughts: CO₂ is Your Ally, Not Your Enemy
So the next time someone tells you CO₂ is “just a waste gas,” you’ll know better. It’s not just something to be exhaled and forgotten—it’s a critical factor in endurance, altitude adaptation, and overall respiratory efficiency.
By training your CO₂ tolerance, you’re not only improving your altitude performance, but you’re also unlocking greater control over your breathing, enhancing your endurance, and ultimately making your climbing experience more efficient and enjoyable.
Did this change the way you think about CO₂? Let me know in the comments, or drop your questions about breath training, altitude performance, or expedition prep—I’d love to answer them in an upcoming post.
And if you’re serious about using breathwork to level-up your endurance, check out our breathwork training programs here at Recal. Let’s get you breathing—and performing—better in the mountains.
Happy training,
– Anthony
1. Free Resources:
2. Five-Week Training Program Options:
- Personal Coaching: One-on-one guidance for $875.
- Online Video Training: Our most popular option for $275.
- Self-Guided Plan: Written instructions in PDF format for $75.
Why This Matters
Proper breathwork training doesn’t just help you survive at altitude—it can be the difference between accomplishing your goals — or not. By following a breathwork training program in advance of your trek, climb, race, or other endeavor in the mountains, you can: improve your CO2 tolerance to feel less breathless, strengthen your respiratory muscles, refine your breathing mechanics, keep your oxygen saturations levels high, feel more in control, improve overall movement economy, improve endurance, and ultimately ENJOY your time in the mountains more.
Ready to take the first step? Explore Recal’s training program options or sign up for the next workshop to experience the transformative power of breathwork training first-hand.
Steps to Begin Your Training
Get In Touch
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Conclusion: There's Now a Better Way to Train for Altitude
Recal’s High Altitude Breathwork Training program equips you with the tools and techniques needed to handle high altitudes confidently. Don’t let altitude concerns hold you back—embrace this comprehensive training program and embark on your adventure with confidence.
Once again, I’m Anthony. From all of us here at Recal, we wish you the best of luck in your upcoming adventures. See you on the mountain soon!
Happy Training,
Anthony and the Recal Team
~ Message from Recal ~
Thanks for stopping by our blog. Here at Recal, we offer breathwork-based coaching to help you prepare for life’s greatest endeavors.
The latest program we offer is High Altitude Breathwork Training to get you ready for the mountain, even if you live at sea level. We also created Guidebook to use as a daily journaling tool; it has helped leaders around the world live more focused and fulfilling lives.
If you’re curious about our Guides, click the links below to submit your information and receive a free digital copy:
We also have a strategic partnership with Oxygen Advantage and use their products (like mouth tape for sleep and SportsMask for altitude training) to help our community become better leaders through breathwork training and proper breathing habits. You can view their online breath courses and products by clicking here.
We stand by the things that we offer and promote – and proudly use them ourselves.
If you have any questions, we’re here to help: email us at hi@recaltravel.com.
Disclaimer: results vary across clients and past performance does not guarantee future results. Response to altitude is very individual and depends on many factors. We always caution our clients to adhere to the advice of traditional acclimatization and local mountain guides.