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Hiking At Altitude


Hiking at altitude presents two special concerns: oxygen deprivation and sun exposure.

Oxygen deprivation:

While each person's sensitivity to oxygen deprivation is unique, most will feel little below 2,000 m. However, a headache and stomach discomfort to a varying degree may be common symptoms above that. And for many, along with heavy breathing, this may be all they will experience to 6,000 m. Most hikers are willing to put up with this for the positive experience of the mountain and the sense of accomplishment.

To combat these symptoms hikers should drink more than they feel they need. In situations of declining oxygen, blood tends to thicken making oxygen dispersal in the body less efficient. Where one to two litres of water per day may be adequate at sea level four litres might be optimum at 5,000 m. As breathing through the mouth eliminates water, nose breathing is recommended. Rather than stopping regularly to pant, maintaining a pattern of one breath per step provides a better method of air intake.

In addition, eating more than one wants is also helpful. While nausea reduces the desire to eat, the body has an increasing need for nourishment. High calorie meals are recommended, supplemented with sweets.

A slow ascent offsets the negative symptoms of altitude such as nausea and headache. This may involve adopting a pace that seems 'too easy'. While it may seem too easy for the muscles, it is necessary to allow the body time to adjust to declining oxygen levels.

An alternative to a slow hiking pace, is repeated and frequent stops. Thus the effective rate of ascent is the same as though one had a slower steadier pace. The wise hiker takes the time to enjoy the sights on the way up and saves his hurrying for the descent.

Distances covered and pace at altitude may seem quite modest by an experienced low-altitude hiker's standards. Those who don't feel they have had enough of a workout after reaching the planned destination can always take side trips.

Forays up higher than the camp and back down improve the body's acclimatization to altitude. Depending on energy levels, several of these at the end of the day may suffice. The key is to take a conservative approach to the required part of the trek and a more liberal one for side trips.

A low-grade headache may be a constant companion above 3,000 m. and nausea may not be far behind. Sleep may be difficult and light. There can also be a general sense of not-being-well, with flu-like symptoms. Remedies such as gravol or aspirin can help but it is better not to mask the symptoms. Aspirin has the added advantage of thinning the blood so may be the better choice over other anti-inflammatories.

Another problem with oxygen deprivation is that it may lead to drowsiness and lethargy and reducing the ability to focus on the activity at hand. During rest stops the tendency is to relax so much as to want to sleep. Succumbing to this may lead to a need for emergency evacuation from the mountain. Another symptom of mountain sickness is the extra effort required to remain focussed on the task and the dangers. This is not common below 5,000 m.

The truly dangerous conditions are pulmonary edema and cerebral edema, with the latter the most dangerous. These terms refer to an excessive amount of water building up in the lungs in the first case and around the brain in second. If these should happen an immediate descent to a lower altitude is required. While some people may experience symptoms of acute mountain sickness at 3,000 m., for most it won't occur until 4,500 m. or higher.

While the hiker may notice little effect at 1,000 m. his body is actually making its first adjustment and that is an increase in rate of respiration. The body will continue to make adjustments to compensate for lack of oxygen. There will be an increase in the pressure in the pulmonary arteries supplying blood to the lungs. At the same time capillaries retrieving oxygen from the lungs will become more perfused with blood. Over time, at altitude, there will be a gradual increase in the concentration of oxygen-carrying red blood cells.

Although respiration increases, possibly somewhat unexpectedly, there is no corresponding stress put on the heart. In fact, the heart is more likely to be strained with heavy exercise at sea level than at altitude. At sea level the amount of blood that can be supplied to the muscles by the heart is the limiting factor in exercise. Where at high altitude the amount of oxygen that can be taken in by the lungs is the limiting factor, not the heart's pumping. As such the capacity for exercise decreases with altitude. The effective oxygen available at 5,500 m. is about half that at sea level.

At sea level only three per cent of the body's intake of oxygen is required for the muscles involved in breathing. At high altitude the oxygen required for the breathing process becomes a severe limiting factor to exercise capacity. In colloquial terms, you seem to be using most of your strength just breathing.

Again oxygen deprivation stress varies with the individual and acclimatization and to a lesser extent cardio-vascular fitness. However, for many new to altitude, but fit, this may become apparent above 5,000 m. Hikers may have to stop and catch their breath going down as well as up.

About 80 per cent of a body's acclimatization occurs within 10 days and 95 per cent within six weeks at altitude. This acclimatization seems to decline at about the same rate it had increased. So if the plan is to ascend several mountains, it is best to start with the smaller ones and progress to the higher ones.

Somewhat ironically, youth and fitness provide no advantage in acclimatizing and avoiding high altitude sickness. There is anecdotal evidence suggesting that those over 25 years of age adapt more readily than those under. Fitness may allow a person to climb more efficiently.

While it doesn't apply to any Footprints' tours, the body will only acclimatize to the oxygen available up to about 7,500m. Height above that in mountain climbing lore is called the 'dead zone'. Above that height body condition only deteriorates, even at rest. Limiting time at that level is the only solution.

Intense Sunlight:

The problem of high altitude sunlight is a function of the nature of the air. It is less dense and as such provides less screen from the sun's rays. A deeper richer blue lets you know that there is less air protecting you.

Sunburn, which occurs in half an hour at sea level, takes only six minutes at 3,000 m. People should dress and use sunscreen with this in mind. Cool temperatures and a breeze can easily lull one into forgetting that sunburn is occurring rapidly. In fact, a wind can augment sun damage. Most people remember the obvious areas of sunburn such as arms, legs and face. Backs of the hands are the most often forgotten. As well sunburn to the eyes is a critical concern.

The headache that accompanies oxygen deprivation can be aggravated by the effect of intense sunlight on the eyes. Sunglasses are important to reduce the glare. Increasing altitude amplifies the effect of an already strong equatorial sun. This can be further compounded by glare off ice and snow which occurs above 4,500 on African mountains. While there is comparatively little ice or snow on a Footprints tour, nevertheless this should still be considered. About 75 per cent of the harmful sun's rays will be reflected up from snow and ice.

Sunglasses provided adequate protection but wrap around goggle-like sun protection is better.

Sun is a critical concern for Footprints tours in Africa. It is direct, compared to the more oblique angles north or south of the equator. While most of the high mountains in Africa are near the equator, Mt. Kenya is directly on it.

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Hiking at Altitude

Forays up higher than the camp and back down improve the body's acclimatization to altitude. Depending on energy levels, several of these at the end of the day may suffice.. Read More »

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