How to Use your Breath to Prepare for High Altitude

Mount Kilimanjaro

What happens to your Breathing at Altitude?

The challenge that climbers or hikers are faced with when attempting to reach the summit of a mountain like Kilimanjaro or Everest, is the lower air pressure.

At sea level the percent of oxygen in the air is 21% and this does not actually change at altitude, but the number of oxygen molecules you can inhale per breath is reduced, due to the lower atmospheric pressure. This will reduce the amount of oxygen that reaches the lungs and the blood, leading to hypoxia (low oxygen levels) and making it harder work to breathe as you ascend. As a result you will expend more energy (use up more oxygen) to support the breathing muscles. Once you reach about 2,400 feet, many people can start to experience altitude sickness symptoms.

Your breathing will naturally get harder and faster due to the sensation of breathlessness as you ascend, which causes overbreathing. The problem with this is that overbreathing offloads too much carbon dioxide which reduces oxygen delivery to the tissues, reduces blood flow, and causes respiratory alkalosis where the blood becomes too alkaline. This can cause dizziness and confusion.

Functional Breathing Training

The good news is that there is a lot of preparation you can do with the breath. The first place to start is to become aware of how efficient your current daily breathing patterns are and improve or optimise these. This includes breathing through the nose, breathing light (not over breathing), breathing slow and breathing deep.

I recently worked with one of my swimmers to help her prepare for a Kilimanjaro climb. She had already attended some of my breathing workshops, so already understood the importance of nose breathing, good biomechanics and carbon dioxide (CO2) tolerance, but wanted some direction on what to focus on in terms of breathing to prepare for her climb.

Correct Breathing Mechanics and Respiratory Muscle Training

As each breath will require more effort the higher she climbs, ensuring correct and full use of her diaphragm, intercostal and abdominal muscles involved in inhaling and exhaling is critical. Her swim and breath training over the last few years has taught her to nose breathe during the day and sleep, correct tongue resting posture, and how to use her diaphragm correctly, which includes maintaining good rib cage flexibility. Therefore, for her, the next step is strengthening her diaphragm and respiratory muscles involved in inspiration and exhalation, ready for the extra breathing load when climbing Kilimanjaro.

The brain senses when the diaphragm fatigues and it will prioritise survival, and therefore breathing, over other functions. As a result, blood is stolen from the legs and re-directed to the breathing muscles to keep them going. If this "blood steal" happens when climbing a mountain due to diaphragm fatigue, it could impact your ability to continue the climb.

Stronger respiratory breathing muscles also reduces air hunger and effort, improves gas exchange in the lungs and oxygen delivery to the tissues, and contributes to better functional movement, which will also aid the climb. We worked on a number of breathing exercises to strengthen her breathing muscles. An example of a simple expiratory muscle strengthening exercise that anyone can benefit from in their daily breathing is Exhale Pulsations. Many people do not exhale fully, so stronger exhale muscles gets rid of stale air and makes more space for fresh air to fill the lungs on the inhale.

Exhale Pulsations

Exhale pulsations can be done pretty much anywhere, sitting with good posture, lips together, tongue on the roof of your mouth and focusing on short, sharp exhales from the nose. As you exhale, simultaneously pull your belly button towards your spine. Then let the inhale happen automatically before the next forced exhale. How many can you do maintaining good form on every pulsation? 50? 100? 150? The key is regular practice. Then spend a few minutes focusing on slow, deep breathing to recover.

Simulating High Altitude Training - Intermittent Hypoxic-Hypercapnic Training

Intermittent Hypoxic-Hypercapnic Training involves improving your tolerance to low levels of oxygen and to high levels fo CO2. Athletes use this to simulate high altitude training at sea level to boost their performance. It can also be used to train for high altitudes. This exercise should only be done under guidance and in the absence of any cardiac or serious health conditions as it is quite a stressor on the body, but a good stressor that creates adaptation if you are healthy.

Hypoxic Training

Improving her tolerance to low oxygen can be achieved with a set of 5 strong breath holds during intense physical exercise, with a minute's rest inbetween, once or twice a day. If you wear a pulse oximeter on your finger during this exercise, you can see if your SPO2 drops and are aiming to get oxygen levels down to about 85% (severe hypoxia) on each breath hold. The brain continuously monitors the levels of CO2 and oxygen, so it senses when SPO2 drops and this triggers the spleen to release more red blood cells to increase our oxygen carrying capacity. The kidneys also increase production of erythropoietin (EPO) during hypoxia (low oxygen) which is essential for red blood cell production. If this is trained regularly at sea level, studies show the effects of this improved oxygen-carrying capacity last over the long-term.

Hypercapnic Training

During these strong breath hold exercises, she is also improving her tolerance to high levels of CO2, which will help her deal better with the feeling of air hunger or breathlessness at altitude.

Respiratory Muscle Training

These strong breath holds also give the diaphragm a work out as it will start to contract when the levels of CO2 rise and the chemoreceptors in the brain sends a signal to the diaphragm to contract and inhale, but you are maintaining the breath hold past this point. The diaphragm will keep contracting (your abdomen will start tightening) until you stop the breath hold. This also trains mental resilience!

Slow Breathing

The other aspect to train is the cadence of her breathing at altitude. The natural instinct will be fast big breaths in response to the feeling of air hunger, so she wants to train slow deep breaths in and out of the nose. There are slow breathing exercises you can practise at rest, but also practising slow, controlled breathing during walking (with some hills) or jogging.

There will come a point when she feels that she has to switch to mouth breathing due to the degree of breathlessness, so the key here is to keep it as low and slow as possible to maximise gas exchange in the lungs. One of the problems with mouth breathing is that it tends to trigger a higher, faster, chest-driven breath, so we have to train ourselves to inhale and activate the diaphragm to trigger a deeper breath.

Being a swimmer gives her an advantage here. She has attended my "Find Your Flow: Breathwork for Swimmers" workshop and also attends my weekly SwimTech Club sessions, so she has learnt to automatically breathe in through the mouth and still recruit the diaphragm, so she can take a deep breath and maximise oxygen uptake in the alveoli (air sacks) deep in the lungs.

How to Breathe During the Ascent

To summarise, these are the breathing strategies to try and maintain during the ascent.

• nose breathe as much as possible

• slow, controlled breathing

• full, low breaths instead of fast, rapid chest breaths

• if switching to mouth breathing due to breathlessness, keep it low, slow and controlled

If you take a pulse oximeter on the climb, you can intermittently put it on your finger to check your oxygen levels (SPO2). Research has shown that your SPO2 will improve with full, low breaths using the diaphragm rather than fast, shallow breaths, where less air reaches the alveoli (air sacks) in the lungs.

Whether you are considering climbing a mountain, or are an athlete looking for ways to boost your performance, improving your breathing mechanics, respiratory muscle strength, CO2 tolerance, slowing your breathing rate, will all help improve your oxygen uptake and delivery, your resilience and mental calm during physical exercise.