Tanzania Exploration Tours and Safari’s

Acclimatisation on Mt Kililmanjaro

The Ultimate Analysis of High Altitude Acclimatization on Mt. Kilimanjaro

Climbing Tips for Beginners

Climbing Mount Kilimanjaro is the challenge of a lifetime and an ultimate test of your stamina, determination, and fortitude. You should be ready to walk long distances through pristine wildlife, spend nights under the blue sky in tents, and virtually live in the wilderness. Our expert guides will lead your way through the wild trails of Kilimanjaro all the way to the top, taking care of all expedition arrangements.

Yet, there is something that is far more important – physiological adaptation of your body to the abnormal altitudes of Kilimanjaro. State-of-the-art equipment and the most accomplished guides will not be able to make your dream come true if the onslaught of Acute Mountain Sickness happens.

Understanding the principles of high-altitude acclimatization is very important in mountain climbing, especially for beginners. In this article, you will find information on why it is important for climbers to acclimatize.

In short, to acclimatize to the altitudes of Kilimanjaro means to develop certain physiological adaptations of your body to survive in the decompressed environment with abnormally low levels of oxygen. Such adaptation is the most important issue in mountaineering, and it is directly impacted by your fitness, good equipment, adequate supplies, and professional crew. Essentially, all these arrangements are made to simplify the process of adaptation to abnormal altitudes. We will discuss it further in greater detail.

What is abnormal in regards to high altitudes?

Before we start explaining how the process of altitude adaptation (acclimatization) works, you are probably interested in what is really abnormal at the slopes of Kilimanjaro, and what impact does this abnormality has on climbers.

As we know from elementary physics, the higher we go, the lower the barometric pressure becomes. For example, at sea level oxygen is approximately 760 mmHg, while at Uhuru Peak (5,895 m) a barometer will show something between 350-352 mmHg, meaning that the density of air is reduced twofold. As a result, there will be substantially less pressure that keeps the molecules of oxygen together. To put it simply, the distance between them increases, and therefore, a fewer number of oxygen molecules are inhaled with each breath. This is what leads to well-known symptoms of discomfort; headache and fatigue, for example.

The oxygen saturation level of a human

Assuming that the majority of the world population lives at altitudes of less than 1000 m/3280 f above sea level, the oxygen saturation of their bodies is 100%. On a biological level, our blood cells are supposed to contain a certain ‘normal’ amount of oxygen molecules to make sure that our brain and other organs are supplied with this vital “fuel” to support our cognitive abilities and overall existence.

The correlation between oxygen saturation level and different heights

As illustrated above, the higher we ascend, the lower the number of oxygen molecules per breath is available. Thus, our bodily oxygen saturation decreases, resulting in important physiological reactions.

The following table illustrates how the average oxygen level of an ordinary human correlates with altitude increases:

SEA LEVEL100%100%
Your expedition will start from Moshi, which stays at 890 m above sea level.
The process of Kilimanjaro acclimatization to high altitudes begins.
5000 M/16404 F53%80%LA RINCONADA
The highest known human settlement is located at 5100 m.
It is located at 4645 m above sea level. You will start your final leg of the journey to Uhuru Peak from here.
6000 M/19685 F47%75%KILIMANJARO PEAK (5, 895 m)
Though you are likely to experience some discomfort at this altitude, humans can live at this altitude. The record is 2 years of consecutive habitation.
8000 m/26247 f36%THE DEATH ZONE
Human beings are physiologically not capable of acclimatizing above this level. Though short-term stay is possible (e.g. during the Everest and other eight-thousanders climbs), prolonged exposure will lead to lethal outcomes.

As you see, the higher a climber ascends, the lower the level of his blood oxygen saturation becomes. A low amount of oxygen in the blood is the cause of different physiological distresses. For example, with less than 65% of blood oxygen saturation, a person is likely to demonstrate symptoms of impaired thinking. Should it drop below 55%, a human may lose consciousness. Any further reduction may have a lethal impact.

Oxygen molecule saturation level on Mount Kilimanjaro

Mount Kilimanjaro’s height is 5,895 m (19,340 f), and research says that the average blood oxygen saturation level of a human being there is roughly 75-80%. That means that though this reduction in oxygen level is definitely not critical, it is sufficient to cause extremely unpleasant experiences if high-altitude acclimatization rules are ignored. These rules are discussed in detail below.

It is, however, quite obvious that the highest point of Kilimanjaro is substantially below the ‘death zone’ of 8000 m. With proper acclimatization techniques in mind, you may definitely stay here a considerably long time. For example, our paragliding expedition spent two nights in the crater while finding a proper starting spot, while the BASE-jumping expedition spent three nights at the peak waiting for favorable weather conditions.

We have special crater camping tours, allowing the climbers to explore the beauty of Uhuru Peak and the surroundings in full.

What impact does it have on the climbers?

In short, adaptation to abnormal living conditions causes some physiological distress in humans, which takes the forms of headache, nausea, loss of appetite, and fatigue.

As long as the body is not accustomed to living in an environment with reduced oxygen levels, our brains start sending signals that something is going wrong and that we should do something in order to restore the normal conditions of our biological existence. From the medical point of view, these signals are known as the symptoms of altitude acclimatization. They should be taken very seriously, as it is them that inform you and your guide about your acclimatization progress.

Mild acclimatization symptoms (slight fatigue, nausea, and a slight headache, may be relieved with medication show that you have started to acclimatize. Although it may be irritating, it is normal and necessary. You will not necessarily have them, but if you do – don’t worry. Most likely, they will disappear the next day.

Many people (actually, over 30%), especially those who decide the long Kilimanjaro climbing programs (over 8 days in duration), feel only minor symptoms, or no symptoms at all as their bodies get adapted to the altitude over a longer period. The process is almost unnoticeable to them.

Acclimatization process of a human being

Once you enter the zone of abnormal altitude, your brain starts sending signals that something is wrong, and the resources of your body should be marshaled to ensure protection. At the same time, the neurological system of humans is very sophisticated – it fathoms that for some reason we should continue ascending, and instead of ‘ordering’ the body to descend, it commences to prepare it for surviving in the decompressed atmosphere.

It is only when our brain senses that the resources of our body are not sufficient to ascend further (or we have not properly prepared our body for the higher elevation) – it signals that there is no other option but to descend immediately (see ‘strong symptoms of AMS below).

The elements of adaptation to high altitude

A body of a human being has four main techniques for getting adapted to the shortage of oxygen molecules in the air. Thus, as you are ascending, the following changes take place in your body:

  • You start to breathe more intensively, frequently, and deeply;
  • The blood structure slightly mutates – the number of the red blood cells grows, thus increasing their oxygen “carrying capacity”;
  • A certain amount of oxygen is released from hemoglobin into the blood;
  • There are some “reserve places” in the lungs of a human body, which are normally not used. Increased pressure in the pulmonary capillaries “pushes” the blood there, helping the body to get more oxygen.

It is important to remember that these adaptations are not instantaneous. Your body definitely can acclimatize to Kilimanjaro altitudes, but it needs time to do so. The higher your climbing point is, the more time your body needs to acclimatize.

How long does altitude acclimatization take?

There is no universal formula that can be applied to calculate the time necessary for getting acclimatized to a certain altitude. The time to acclimatize to the heights of Mt Kilimanjaro is very individual. At the same time, the fusion of our practice and statistics show that the climbing programs with 7 or more days on the Mount are marked with higher success rates than the 5 or 6-day ones.

In addition, acclimatization time also varies by route. Practically, the steeper the route is – the more time for acclimatization will be necessary. For example, the success rate on Lemosho 6-day programs is much higher than on 6-day Umbwe route trekking adventures. Our universal advice is to take longer programs in order to make your acclimatization transition smoother and less noticeable.

Why taking a long Kilimanjaro climbing program is better

For all our climbers we do seriously recommend 7,8 and 9-day climbing programs because of the altitude adaptation zone concept.

The concept of acclimatization zone refers to a certain altitude span where a climber does not feel the symptoms of altitude mountain sickness.

To illustrate, for many people the first acclimatization zone is 3000 m/9842 f – 3800/12467 r. It means that having reached the lower point, and spending some time there, a person will be comfortable staying within this range. In order to ascend higher, however, this person needs to spend a night at 3700 m/12139 f in order to increase this span.

Broadening one’s acclimatization zone involves some discomfort, which fades away over time. For example, feeling a small headache and nausea upon arrival to Mti Mkubwa Camp (3095 m/ 10155 f) is quite natural. Spending a night there will most likely reduce or neutralize discomforts altogether, meaning that the body got accustomed to this zone.

The longer program you take the more time your body has for broadening the borders of this zone, and the less discomfort you will experience in the course of the acclimatization process. Making small altitude increases every day will be much less stressful for your body than if you make ‘elevation jumps’. As a result, you will feel much, much better and your hiking experience will be a pleasant one. Thus, it is highly recommended to make your altitude acclimatization time as long as possible.

The Rules of Good Acclimatization

In spite of the fact that your body has an in-built mechanism for adapting to high altitudes, in order to make this process successful it is vital for you to follow these rules:

Acclimatization hikes are very important for your climbing success. Though you may be reluctant to do them (after a tiresome daily walk from the first camp to the second, making another hiking endeavor may seem to be an unpleasant and unnecessary challenge), ignoring them may put the culmination of your trip at risk. Send the signal of the future altitude increase to your body – it will take care of the rest.

  • If you have not been in any other high-altitude (above 5,000 m) expedition during the past three months, we strongly recommend you to choose the 7/8/9-day climbing program;
  • Choose one of the beginner-friendly climbing routes. Our top recommendation is the Lemosho Route.
  • Make sure that your climbing itinerary sticks to the “walk high – sleep low” idea, meaning that the camps are located slightly below your daily trekking adventures. If you are not traveling with us make sure that the itinerary given by your tour operator follows this principle.
    To illustrate this point – on the 3rd day of our 7-day Lemosho climbing adventure, the explorers of Kilimanjaro hike from Shira 1 Camp (3505 m/ 11499 f) to Shira 2 Camp (3900 m/12795 f). The increase in altitude is significant, and your body is not ready for the overnight acclimatization challenge at Shira 2.
    In order to boost the altitude adaptation processes of your body and to ensure your comfortable overnight stay at Shira 2, you will make an acclimatization hike to a higher point on the way to Lava Tower, eventually reaching the 4110 m/13484 m point. Then, you will return to Shira 2 Camp for an overnight stay. This hike to a higher altitude, although for a short time, will help your body begin to make the physiological changes to adapt to the elevation change.
  • Remember the importance of the “Pole-Pole” (slowly-slowly) walking style. Even if you believe that you have an unmatched fitness level – always avoid overexerting yourself. We have witnessed many people of ordinary fitness level reach the summit successfully and without any distress, while professional athletes who rushed forward to show how tough they were, have been ultimately evacuated by emergency services. Kilimanjaro climbing is not a competition and there is no place for ‘who will reach first’ bets here.
  • Drink a lot of water. Dehydration at high altitudes is a big issue. Sometimes, you do not feel thirst, but increased water supplies are vital for your body. A minimum of 3-4 liters per day is necessary for an adult.
  • Eat well. Lack of appetite on the Mount is a common problem. However, the process of adaptation to the Kilimanjaro altitude challenge is very energy-consuming. Your body is burning thousands of calories per day to support intensified breathing activity, the extra development of red blood cells, and other vital biological processes. Our diet plans are specifically designed to make sure that your energy supplies are replenished in a timely manner.
  • Take Diamox whenever offered by your guide. We do recommend taking it from the first day of your adventure two times per day. Make sure you take it in the morning and before lunch. Diamox is known to be a diuretic and taking the daily dose before 14:00 will spare you from midnight visits to the washroom.
    Important note:
    Diamox should not be taken in by those who have diabetes or are sulfur-allergic. At the same time, if you have one of these conditions, this is not a reason to abandon your dream adventure. Consider taking our 8/9-day programs to give your body more time for natural acclimatization, and make sure to inform our wildlife adventure experts, who will take care of the necessary arrangements.
  • Follow the instructions of your guides. Even if you are an experienced medical practitioner with many years of emergency situations under your belt – unless you specialize in high-altitude first aid, do trust your guide. Our climbing leaders are certified Wilderness First Responders or Wilderness First Aid professionals, and they have been well-drilled to react to climbing emergencies in an effective and safe way. Ultimately, it is the guide who bears responsibility for your safe return. While it may escape your attention, your guide is always watching you – he will choose the best walking style for you, he knows which medication to give in which case, and also it is he who decides if circumstances or health factors require that you descend.
  • Training for high-altitude climbing is important. Make an effort to prepare with jogging or start an exercise regime in advance of your climb. Though the impact of physical training on the effectiveness of acclimatization transition is not yet fully explored, a good fitness level will help you to cope with Kilimanjaro trekking challenges more easily.

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