Climbing Mount Everest without supplemental oxygen requires 70 ml/kg/min oxygen uptake capacity and 70 – 100 days of acclimatization

Hello, this time the topic of the blog is about how to get to the top without oxygen equipment. I have researched the topic for three years from different sources and found out which factors influence adaptation to the greatest challenge of the Himalayan peak.

In today’s blog, we will consider cause-and-effect relationships from the conditions of Everest’s solution point (8000 m) to physiological requirements, correlations and consideration of whether, in addition to oxygen uptake and acclimatization time, there is an adaptation factor X or not. The story could become topics for several degrees, and the fieldwork could be interesting, but challenging.

Interesting reading experiences!

Lack of oxygen is the biggest challenge on Mount Everest

The summit ridge of Mount Everest has 1/3 the oxygen compared to sea level

When moving from sea level to a higher air pressure, the partial pressure of oxygen also decreases in the same proportion. At the top of Everest, at an altitude of just under 9,000 meters, the air pressure is about 30% of sea level, so the partial pressure of oxygen is correspondingly 30% of sea level, i.e. significantly less oxygen is available, which means that mountain climbing is almost impossible.

“When climbing Mount Everest, the biggest challenge is the amount of oxygen above 8,000 meters.” – Jussi Haikka

The oxygen uptake capacity drops by 70% when going from sea level to the top, which means that the maximum oxygen uptake capacity of 70 ml/kg/min drops to the level of 21 ml/kg/min. Correspondingly, the oxygen uptake capacity of the aerobic threshold decreases from the level of 40 ml/kg/min to the level of 12 ml/kg/min, which theoretically enables an ascent of 1000 meters in 4 hours with the equipment, but in practice in 8 hours.

The amount of oxygen is also affected by the season and the weather. In summer, there is more high pressure, so more oxygen is available. In addition, in windy weather, more oxygen is used to overcome wind resistance, and in cold weather, the body uses energy and oxygen in the same way as a cold car engine uses fuel. You should literally visit the top during good weather.

During the mountain climbing project, I also got access to public material related to the training of fighter pilots, which tells about human physiology and symptoms of lack of oxygen. I will come back to the topic later when I update the blog.

A flight to an altitude of 8,000 meters? – the body’s physiological function at over 8,000 meters

In order for movement at the height of passenger planes, seven kilometers above the skyscrapers of Manhattan, to be possible without oxygen equipment, the oxygen uptake capacity, i.e. the body’s ability to oxygenate the muscles during exercise, must be good enough at around 65 – 70 ml/kg/min. The level in question corresponds to the level of the maximum oxygen uptake capacity of Olympic skiers. From the above-mentioned measurement unit, you can see that the body mass (77 kg) and portable mass (15 – 20 kg) are relevant, along with the absolute oxygen uptake capacity (l/min).

“If a person is taken directly from sea level to an altitude of 8,000 meters, he will die from lack of oxygen in less than four minutes.” (scientific articles)

If a mountaineer is too high for too long, he develops life-threatening mountain sickness. At an altitude of more than 8,000 meters, the aim is to move as quickly as possible. When moving briskly, however, the body’s oxygen content decreases, so the pace must be optimized so that the minimum time spent at an altitude of more than 8,000 meters is as little as possible, while maintaining the body’s oxygen levels and ability to function in the arctic peak wind. In practice, it means a regular and sufficient supply of energy and hot water during 30 hours of peak performance.

Death Zone

“Above 8,000 meters there is a death zone, just like when crossing a highway. If you stand too long on the highway, you will die.”

At an altitude of 8,000 meters, the body no longer recovers, but begins to die a slow death, so it is not worth spending any extra time there. According to the information I received, 6500 meters is the highest long-term altitude where a person has lived for months. According to my own assessment, the highest possible limit of acclimatization is at an altitude of 7,000 meters, so it is no longer possible to adapt above that for a long time, because the body starts to wear out due to the lack of oxygen. However, there is about 10% more oxygen at an altitude of 7,000 meters than at an altitude of 8,000 meters, so the body does not wear out any more there after the summit. 7000 meters is the highest altitude from which you can rescue on foot and from 6000 meters by helicopter, so it also advocates descending from the summit directly to the C3 base at 7100 meters.

Mountain sickness

Mountain sickness is caused by too little oxygen intake for too long. Finnish doctor of medicine Heikki Karinen has researched and done distinguished field work in the Himalayan mountains and a dissertation on mountain sickness. I have consulted Heikki Karis a few times and read his articles on mountain sickness and its first measures.

Oxygen saturation (PO2) and wrist pulse oximeter

“Oxygen saturation means the oxygen content of the blood, which can be measured with an oxygen saturation or pulse oximeter.” (Medidyne, scientific articles)

Nonin rannepulssioksimetri, Medidyne Nordic

My first sponsor, Medidyne Nordic, has given me a new technology product, a wrist pulse oximeter, where the sensor is on the end of the finger and the meter is on the wrist. The oxygen saturation meter I got is like a reverse car speedometer. If the reading drops too low, the ascent must be interrupted and the altitude must be lowered by 500 meters. When moving, the oxygen content of the blood, i.e. oxygen saturation, is lower than at rest, and monitoring it can be challenging in mountain conditions.

Another way is to use an oxygen saturation monitor while at rest. Mountain sickness usually comes with a delay in relation to the level of acclimatization, ability to acclimatize, increased altitude and speed of ascent and it usually starts in the morning. If the reading of the oxygen saturation meter is too low, you have to get out of the sleeping bag and immediately start descending on the dark and cold mountain to an altitude 500 meters lower.

In addition to Medidyne’s oxygen saturation meter, the Oura smart ring (gen3) is getting an oxygen saturation feature as an update during 2022.

Lake Louise testing

(I write later)

1. Correlation of oxygen uptake capacity (MAX VO2) to summiting Mount Everest without supplemental oxygen

Endurance is crucial when climbing to the top of Mount Everest without supplemental oxygen and Sherpa.

1.1 Correlation of oxygen uptake with peak probability

“According to research from the 1980s, oxygen uptake capacity has a clear correlation with peaking probability.” (scientific articles)

When climbing with oxygen bottles, the height of 8,849 meters corresponds to an altitude of about 6,000 meters in terms of oxygen partial pressure, which means that the oxygen absorption capacity only needs to be 70% compared to climbing to the top without oxygen bottles. In practice, for Marathon, it means less than three hours without supplemental oxygen, and 4.5 hours for oxygen bottle users.

1.2 Oxygen uptake (VO2) testing

(I write later)

1.3 The importance of power output for performance and oxygen consumption

“In an optimal situation, a mountain climber has a relatively high power output, a light body weight and a durable big engine – the heart.” – Jussi Haikka

The body’s ability to generate power is important for performance and oxygen consumption when moving 15 to 20 kg with equipment uphill. For a smaller size, 20 kg basic load in the upper mountains increases the total mass to be carried relatively more than for a larger size mountaineer. The larger volume of a larger body is beneficial both against the effect of frost and in terms of energy and power production. The lightweight mountain climber weighs less, so it is naturally lighter and faster to transport. However, the harsh conditions of the mountains also require momentary power generation ability in difficult conditions, because moving in easy terrain becomes extremely difficult, if not impossible, in a storm.

1.4 Effect of additional range on rate of climb and performance factor

In my own field studies, I have found that 10% additional bearing slows down the speed by a constant 10% (Cooper’s test). Similarly, in my own field studies on a 20-degree uphill, a 10% bearing has slowed down the speed by 20%. So the kilos carried on the uphill are at least double. There is no unequivocal formula, but the conclusion is that the mass to be carried must be lowered and the endurance condition and maximum strength levels must be raised.

“Uphill, a 10% bearing slows you down by 20%.” – Jussi Haikka

While calculating the time from different heights to the top and back, I ended up comparing my own condition with the condition of mountain runner Kilian Jornet, when I knew the time of both in a 10,000 meter run. As a result, I ended up with the fact that compared to Kilian Jornett, my performance coefficient is 1.20. When increasing the load capacity to 20 kg, the difference equalizes to a factor of 1.15. On the other hand, he has more experience of his own limits in the mountains, so the practical performance factor in terms of time is 1.25. The performance factor helps determine the time needed to move in the mountains. However, it is unusable when moving from Everest to steeper terrains.

2. Acclimatization time and altitude


Acclimatization 22 of April 2022

Acclimatization plan, climbing Mount Everest without supplemental oxygen. Acclimatization is shown in the picture in blue, the acclimatization plan is in green. The current situation is shown as a red box. The oxygen saturation readings (SPO2, %) of Sponsor Medidyne Oy’s Nonin Wrist Oxygen meter are shown in the picture above the upper mountain sections. The peak probability is 40 – 60%.

2.1 Acclimatization – adaptation to low-oxygen air

Acclimatization means adapting to high altitude, i.e. thin, low-oxygen air. When moving, a person needs to oxygenate the muscles so that they can do heavy work. When less oxygen is available, movement is heavier and slower.

“Performance at over 8,000 meters without oxygen bottles requires a high oxygen uptake capacity and a long acclimatization period.” – Jussi Haikka

When climbing without supplemental oxygen, acclimatization is crucial and requires an acclimatization period of at least 75 days. The first mountaineering expeditions, which in the 1970s and 1980s conquered the mountain without oxygen bottles, flew to Nepal at the end of February. My solution is to start acclimatization with a five-week period in the Alps in January-February and continue it with a 75-day period in Nepal in March-May. For acclimatization, you can also use the oxygen tents and mountain huts used by top athletes, which are valuable investments.

Acclimatization practically means moving the sleeping height up 250 – 300 meters in height per day. In addition, every third day must be a rest day, because otherwise the strain will become too great over a long period of time. When starting at sea level, the length of the acclimatization period is crucial to performance at 8,000 meters. In addition, moving in several countries and mountains with different operators, as well as the change in mountain weather and the health situation pose logistical challenges for the optimal implementation of acclimatization.

(When climbing with oxygen cylinders, the acclimatization period is typically 30 to 40 days.)

2.2 Acclimatization plan

In the excel table above, you can see my 2022 acclimatization plan. The red box indicates my altitude on the mountain and my progress in the acclimatization plan. The graph shows the realized and planned daily sleeping height in green. Violet has what I estimate to be an 80% acclimatization curve, which rises steadily over a long period of time as winter and spring progress in connection with acclimatization ascents and the construction of upper mountain camps. I have consulted a few times with Dr. Heikki Karis, who thought my plan was good.

The goal is to reach peak readiness on 10.5. by which time the acclimatization curve should be at least at an altitude of 6,500 meters. In principle, the peak readiness to climb to a height of 8,500 – 8,849 meters has been achieved.

According to the statistics of the website, the average weather window of 4 to 11 days (mountain weather at the top -20 C, 10 m/s) falls between the winter season and the monsoon season from 10 to 31 May. in between, with the best day being mostly 23.5. By studying the website in question, you will also find out when it is worth trying to reach the top.

The acclimatization plan must take into account logistical constraints and challenges. For example, the route up from the base camp will not be opened until April 1st, when the operator starts operating in the base camp. A possible illness and bad weather in April-May can delay acclimatization and summit readiness by 1 to 2 weeks, which may constitute a decisive delay before the weather window opens for the summit attempt.

As winter and spring progress, I update the acclimatization plan and the red box in the acclimatization plan weekly, so you can monitor my operational situation in terms of peaking opportunities.

2.3 The acclimatization period begins

In January, a 100-day acclimatization period begins in the Alps, which ends with summit readiness in Nepal on May 10. Welcome to my website again and please also tell a friend.

Thanks for reading, next time there will be something lighter on the blog!

3. Ability – Is there adaptation factor X, i.e. a special ability to acclimatize?

“Acclimatization means adapting to low-oxygen air, which requires time and altitude and possibly adaptation factor X, i.e. the ability to acclimatize.” – Jussi Haikka

In the past three years, I have heard that fitness, i.e. the ability to absorb oxygen, does not always correlate with the ability to acclimatize. On the other hand, oxygen is the same at high and low levels, and scientifically, the oxygen uptake capacity of the same body works in the same ratio only when the amount of oxygen is changed. It remains to be considered and observed whether there is an ability to acclimatize, i.e. adaptation factor X, which is the body’s ability to adapt to low-oxygen air as a function of time. In practice, an athlete with a higher oxygen uptake capacity copes better in physical exertion, even though less oxygen is used, but if the body of an athlete with a higher oxygen uptake capacity cannot physiologically adapt to the changed conditions, then acclimatization is slower, which becomes an obstacle to rising above 8000 meters.

“In mountain climbing from 8,000 meters up, you probably need three different factors: oxygen uptake capacity, acclimatization and possibly factor X, which is the ability to acclimatize.” – Jussi Haikka

Through practical experience, it has been found that during the acclimatization period, the sleeping altitude can be increased by 250 – 300 meters in height per day, and every third day must be rested. Acclimatization can be accelerated by doing acclimatization climbs by moving about 1000 to 2000 meters above the sleeping height. When moving, the body naturally has a lower oxygen state than when completely at rest.

I have been informed that the ability to acclimatize at 4800 meters altitude correlates with the ability to acclimatize in the Himalayas. In my case, after three days of acclimatization, I haven’t noticed anything out of the ordinary when climbing Mont Blanc, so I can assume that everything will go at least up to an altitude of 7100 – 8000 meters without problems, but that’s where the final challenge begins.

“Acclimatization ability at 4,800 meters altitude correlates with acclimatization ability in the Himalayas.” (scientific articles)

4. Mountain weather resistance


4.1 Air pressure affects the amount of oxygen in the air

(I write later)

4.2 Air temperature affects the efficiency of the respiratory system

(I write later)

4.3 Wind increases the muscles’ need for oxygen

(I write later)

4.4 Snowfalls increase the muscles’ need for oxygen or prevent mountain climbing

(I write later)

4.5 Routes and fixed ropes

(I write later)

5. Muscle energy level

5.1 Load carrying capacity

(I write later)

5.2 Ability to survive a mountain storm

(I write later)


Copyright Jussi Haikka 2022