From Kilimanjaro to Everest: how fit do you have to be to climb a mountain?

Climbing a mountain has more to do with how your body deals with altitude, which you can’t control.
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Julien Periard, University of Canberra and Brad Clark, University of Canberra

Since the commercialisation of high altitude mountaineering in the 1990s, the number of climbers has increased significantly. Mount Kilimanjaro, perhaps the most popular mountaineering trip in the world, now attracts around 40,000 climbers per year. And the number attempting summits above 8,000m (such as Mount Everest) has risen exponentially.

The main challenge for all climbers is the decrease in barometric pressure and thus reduction in oxygen availability as altitude increases. The severity of altitude is defined as low (500 to 2,000m), moderate (2,000 to 3,000m), high (3,000 to 5,500m), or extreme (above 5,500m).

Remaining at high altitudes severely affects our physical capacity, cognitive function, body mass and composition, and ability to ward off illness.

If we don’t acclimatise or stagger our ascent, we’re at greater risk of acute mountain sickness, high altitude pulmonary oedema (excess fluid in the lungs) and cerebral oedema (fluid on the brain). These illnesses are all commonly characterised by symptoms such as headache, loss of appetite, nausea, weakness, light-headedness, and sleep disturbance. The presentation of these illnesses often requires retreat to lower altitudes and in severe cases, evacuation via airlift from camp.

These conditions are among the greatest obstacles to successful summit attempts, particularly when ascending quickly.

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Read more:
How does altitude affect the body and why does it affect people differently?

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Acclimatising

Being fitter does not protect against altitude-related illness, nor does it ensure tolerance of the physiological challenges associated with high altitude exposure.

So acclimatisation is the more important factor. Acclimatisation is the process your body follows to adapt to the drop in oxygen availability. This is the best non-pharmaceutical strategy to prevent altitude sickness.

Mountaineers and trekkers can achieve acclimatisation by staying at moderate altitude (2,000-3,000m) for a few extra nights, then implementing a staggered ascent to higher altitudes. Gains in altitude should be between 300 and 600m of vertical elevation per day.

While many commercial trek schedules include rest days and acclimatisation days, some involving less technical climbing often ascend quite quickly. Some groups will ascend Kilimanjaro in four to five days (5,895 m).

To prepare for more rapid ascents, mountaineers may include some pre-trek acclimatisation, using natural or artificial environments to encourage their bodies to adapt.

Acclimatisation using artificial environments is known as “acclimation”. It can be achieved by either hypobaric hypoxia (normal oxygen concentration, lower barometric pressure), or more commonly via normobaric hypoxia (normal barometric pressure, lower oxygen concentration) using altitude tents or environmental chambers.

Technical experience, fitness and acclimatisation are equally important.
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Of the two approaches, hypobaric hypoxia appears to be better for acclimation, though it relies on access to a hypobaric chamber or an ability to live at moderate/high natural altitude.

Although still relying on specialised equipment and expertise, more environmental chambers available mimic normobaric hypoxia. In some instances, you can even use tent or mask systems in your own home.

Acclimatisation can also mitigate the effects high altitude will likely have on exercise performance.

Training

Although fitness is not related to incidence rates of altitude sickness, trek schedules typically require many hours of hiking, often carrying a loaded pack, over at least four to five days. When combined with the gain in elevation, this means seven to eight hours per day of hiking at a moderate intensity, often over varied terrain.

So a program of targeted training will ensure trek participants are able to meet the strenuous demands of high altitude hiking and mountaineering. Evidence suggests fitter hikers report a lower sense of effort and lower levels of fatigue during high or extreme altitude trekking.

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Studies have also found experienced mountaineers don’t need to expend as much oxygen, which is valuable when there’s less of it available. So to further prepare for high altitude expeditions, trek participants should focus on building fitness over several months by trekking at lower altitudes and carrying loads of 20-30kg for several hours over varied terrain.

This can be extended to higher altitudes (3,000m to 4,000m) and several consecutive days and weeks to allow for developing the strength required to tolerate the rigours of extreme mountain climbing. This is especially important as muscle mass and body fat losses occur during the expedition.

For ascents above 8,000m such as Mount Everest, the trekking company will usually have specialised training approaches. This may involve at least one year of training in which trekking time, distance and altitude are increased progressively, as summit day can take up to 20 hours. Experience in high altitude climbing and sumitting peaks between 6,000m and 8,000m is also required before attempting peaks of this altitude.

Staged ascents and considered approaches to acclimatisation are most likely to protect against altitude illness and ensure trek success. This involves using a planned approached to climbing with altitude targets allowing for acclimatisation.

Improving overall fitness and gaining mountaineering experience will prepare trekkers for the physical, psychological and technical challenges presented by high and extreme altitude adventures.

Julien Periard, Associate Professor, University of Canberra and Brad Clark, Researcher, University of Canberra

This article was originally published on The Conversation. Read the original article.

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How does altitude affect the body and why does it affect people differently?

How well you’ll cope on a mountain has little to do with how fit you are.
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Brendan Scott, Murdoch University

Every year, thousands of people travel to high-altitude environments for tourism, adventure-seeking, or to train and compete in various sports. Unfortunately, these trips can be marred by the effects of acute altitude sickness, and the symptoms vary from person to person. To understand why people are affected differently, we have to look at how the body is affected by altitude.

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From Kilimanjaro to Everest: how fit do you have to be to climb a mountain?

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How is ‘altitude’ different to sea level?

Air is comprised of different molecules, with nitrogen (79.04%) and oxygen (20.93%) making up the majority of each breath we take. This composition of air remains consistent, whether we are at sea level or at altitude.

However, with altitude, the “partial pressure” of oxygen in this air (how many molecules of oxygen are in a given volume of air) changes. At sea-level, the partial pressure of oxygen is 159 mmHg, whereas at 8,848m above sea level (the summit of Mt Everest), the partial pressure of oxygen is only 53 mmHg.

At high altitudes, oxygen molecules are further apart because there is less pressure to “push” them together. This effectively means there are fewer oxygen molecules in the same volume of air as we inhale. In scientific studies, this is often referred to as “hypoxia”.

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Author provided/The Conversation, CC BY-ND

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What happens in the body in high altitudes?

Within seconds of exposure to altitude, ventilation is increased, meaning we start trying to breathe more, as the body responds to less oxygen in each breath, and attempts to increase oxygen uptake. Despite this response, there’s still less oxygen throughout your circulatory system, meaning less oxygen reaches your muscles. This will obviously limit exercise performance.

Within the first few hours of altitude exposure, water loss also increases, which can result in dehydration. Altitude can also increase your metabolism while suppressing your appetite, meaning you’ll have to eat more than you feel like to maintain a neutral energy balance.

When people are exposed to altitude for several days or weeks, their bodies begin to adjust (called “acclimation”) to the low-oxygen environment. The increase in breathing that was initiated in the first few seconds of altitude exposure remains, and haemoglobin levels (the protein in our blood that carries oxygen) increase, along with the ratio of blood vessels to muscle mass.

Despite these adaptations in the body to compensate for hypoxic conditions, physical performance will always be worse at altitude than for the equivalent activity at sea level. The only exception to this is in very brief and powerful activities such as throwing or hitting a ball, which could be aided by the lack of air resistance.

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Read more:
Tall tales misrepresent the real story behind Bhutan’s high altitude tigers

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Why do only some people get altitude sickness?

Many people who ascend to moderate or high altitudes experience the effects of acute altitude sickness. Symptoms of this sickness typically begin 6-48 hours after the altitude exposure begins, and include headache, nausea, lethargy, dizziness and disturbed sleep.

These symptoms are more prevalent in people who ascend quickly to altitudes of above 2,500m, which is why many hikers are advised to climb slowly, particularly if they’ve not been to altitude before.

It’s difficult to predict who will be adversely affected by altitude exposure. Even in elite athletes, high levels of fitness are not protective for altitude sickness.

There’s some evidence those who experience the worst symptoms have a low ventilatory response to hypoxia. So just as some people aren’t great singers or footballers, some people’s bodies are just less able to cope with the reduction in oxygen in their systems.

There are also disorders that impact on the blood’s oxygen carrying capacity, such as thalassemia, which can increase the risk of symptoms.

But the best predictor of who may suffer from altitude sickness is a history of symptoms when being exposed to altitude previously.

How are high-altitude natives different?

People who reside at altitude are known to have greater capacity for physical work at altitude. For example, the Sherpas who reside in the mountainous regions of Nepal are renowned for their mountaineering prowess.

High-altitude natives exhibit large lung volumes and greater efficiency of oxygen transport to tissues, both at rest and during exercise.

While there is debate over whether these characteristics are genetic, or the result of altitude exposure throughout life, they provide high-altitude natives with a distinct advantage over lowlanders during activities in hypoxia.

So unless you’re a sherpa, it’s best to ascend slowly to give your body more time to adjust to the challenges of a hypoxic environment.

Brendan Scott, Senior Lecturer (S&C), Murdoch University

This article was originally published on The Conversation. Read the original article.