Why is this a problem? 

Mouth-breathing at altitude dries and irritates the respiratory tract, increases the risk of dehydration, and can trigger exercise-induced bronchoconstriction. We recognize that mouth-breathing is unavoidable at times (highly dependent on your CO2 tolerance). But habitual mouth breathing at altitude comes with three devastating consequences:

• No heating/humidification/filtration: Nasal sinuses warm and humidify incoming air; mouth breathing injects cold, dry air straight into the lower airways. On high-altitude climbs, that matters: dry, cold air increases airway irritation.

• Higher risk of exercise-induced bronchoconstriction: Classic pulmonary physiology shows that mouth breathing can worsen airway narrowing during exercise; nasal breathing tends to protect against that response. If your airways tighten at altitude, your breathing will spiral downward. And fast.

• Wasted mechanics: Mouth-breathing creates shallow, upper-chest patterns, which reduce efficiency. Nasal breathing engages diaphragmatic breathing (low and full breaths). 70% of the oxygen that diffuses into your blood happens in the lower 30% of your lungs. Get the air down there.

What to do about it? 

Train your nasal breathing. Your nose is a muscle, and if you don’t use it, you lose it. This is especially true for those with a deviated septum or excessive mucus production.  

To train your nose muscles, begin focusing on breathing as much as possible through your nose, especially on your inhale. During workouts, in between sentences while talking, and particularly at night. If you wake up with a dry mouth, you’re probably breathing with it at night. We recommend MyoTape to help you make the switch to nighttime nose breathing. 

When you train for your climb at the gym or outdoors, you can use progressive re-education to activate your nose muscles. Start with nose-only breathing during lower-intensity movement, then layer in intensity while maintaining nasal flow until it’s no longer possible, and revert to Nose-Full-Low (more on that below) as a safety net.

If you have a history of bronchoconstriction or asthma, work with a clinician and consider nasal training and warming strategies as part of your preparation. You’ll stay drier, reduce your exercise-induced bronchoconstriction risk, and protect your airway function for the long haul.

Why is this a problem?

Shallow, chest-dominant breathing leaves your strongest respiratory muscle, the diaphragm, barely engaged. Yet most people breathe that way. Learning to breathe low and fully expand your rib cage properly distributes the workload and keeps your oxygen delivery system stable and efficient, especially when the trail steepens and the air thins.\

What to do about it?

During your training, use the Nose-Full-Low technique. Using your nose, take full breaths (big, diaphragmatic inhalations), let the air fill your belly, and engage your diaphragm. You can also practice hook-lying diaphragmatic breathing (see details below) and use a diaphragm-training belt, such as the Buteyko Belt. This not only strengthens your diaphragm but also gives you tangible physical feedback on the location of movement with each breath. You will soon breathe subconsciously into your belly.

Another technique you can use during training is balloon breathing, which simply involves using your breath to inflate a balloon. This isn’t just about increasing lung-cage elasticity, though it does that; it’s specifically useful because it trains for pressure breathing on the mountain.

On the mountain, you’ll often hear guides mention the term pressure breathing. But what does that mean? Basically, it’s a full inhale, then a moderately forceful, slightly pursed-lip exhale that raises airway pressure and helps keep alveoli open and gas exchange more effective despite low ambient pressure. That positive pressure during expiration has been shown in both lab and field settings to increase arterial oxygen saturation and reduce acute mountain sickness symptoms after trekking to high altitude. Training with balloon breathing and positive end-expiratory pressure (PEEP) devices conditions you to use these mechanics without wasting energy. 

Why is this a problem?

As you know, air pressure is lower at high altitudes than at sea level, and, since a gas moves from high-pressure areas to lower-pressure areas, this creates a problem getting sufficient air into your lungs. In other words, the air outside your lungs is at a lower pressure, so it will take more effort to pull it into your lungs. With this extra effort, with  every breath, you’re getting closer to muscle failure for your primary inspiratory muscles (diaphragm and external intercostal muscles). If those muscles fatigue, your breathing becomes shallow and inefficient, which cascades into lower SpO₂, worse exercise economy, and earlier locomotor (leg) muscle fatigue (see: respiratory muscle-induced metaboreflex).

Targeted respiratory muscle training (RMT), like air-resisted diaphragmatic breathing, balloon breathing, and pressure breathing drills, strengthens the muscles that power your inhale and exhale. Research has shown that climbers and endurance athletes who perform inspiratory muscle training (IMT) maintain higher oxygen saturation at altitude than those who don’t. 

Controlled studies of inspiratory muscle training (IMT) show it can attenuate the drop in arterial oxygen saturation at high altitudes. In one notable investigation, IMT increased inspiratory strength and blunted the fall in resting SpO₂ at ~4,880–5,550m compared with controls. In other words, trained respiratory muscles helped keep oxygen levels higher when it matters most.

Combine respiratory muscle training (RMT) with the Nose-Full-Low technique and CO₂ tolerance work, and you’ll be stacking physiological adaptations: stronger respiratory muscles, better handling of high CO₂ in your blood, and improved alveolar mechanics when you use pressure breaths on the mountain.

Slow breathing is always better. Not necessarily. While it’s good below ~7,500 ft, it’s not good during your first hours at a new high altitude. You must be able to increase ventilation when the body demands it; that capacity to up-regulate ventilation without losing technique is our training priority.

Breathwork training is only for elite athletes. No. Respiratory muscle training (RMT) and nasal-breath training are low-risk/low-cost, high-value pieces of proper preparation for any climber aiming for multi-day, high-altitude objectives. 

I can skip acclimatization now that I’ve done breathwork training. Absolutely not. Breathwork training increases your capacity to maintain higher blood oxygen saturation and performance. However, it is not a substitute for slow, sensible acclimatization, good hydration, and listening to your CTSS guides and doctors. If you experience breathlessness that’s out of character, a cough with frothy sputum, crackling sounds inside your lungs, or a high fever, treat it seriously. Seek medical attention and descend immediately. HAPE and other serious altitude illnesses are uncommon but real, and they’re not something breathwork training or willpower can overcome.

Find out which of these four mistakes you might be making. Don’t just guess if your breathing is mistake-free. Find out using the Recal Breath Index discussed at the beginning of this blog. 

It will break down your breathing into two parts:

• The Biochemistry of your Breathing: How efficiently you exchange oxygen and carbon dioxide, regulate blood pH, and deliver oxygen to your muscle tissue. Plus, you will finally get a real, trackable metric for the out-of-breath feeling.

• The Biomechanics of your Breathing: The efficiency of airflow, your lung expansion, and the proper engagement of your diaphragm

Taking the Recal Breath Index is the first step toward identifying both the weakest and strongest parts of your breathing. And most importantly, it will give you insight into what needs extra attention.

If you’re ready to reinforce this work with a focused training plan, reach out to Anthony at anthony@recaltraining.com. A few targeted exercises now can make a real difference on the mountain.