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Running at altitude: what you should know

This is primarily for the Lesotho Wildrun runners, but good general knowledge for running at altitude.

Running at altitude

Preparation is king, and knowledge leads to better preparation – so in the interests of keeping you informed as best we can, here is a little splurge on altitude, and the possible effect it may have on your body.

This is not written to scare anyone at all, and the fact of the matter is is that the Lesotho Wildrun only just journeys into the ‘High Altitude’ zone on day 1 & 3.  More importantly though you are ‘climbing high and sleeping low’ to use a phrase bantered around in mountaineering circles.

There are no specific factors such as age, sex, or physical condition that correlate with susceptibility to altitude sickness. Some people get it and some people don’t, and some people are more susceptible than others. Most people can go up to 8,000 feet (2,438 meters) with minimal effect. If you haven’t been to high altitude before, it’s important to be cautious. If you have been at that altitude before with no problem, you can probably return to that altitude without problems as long as you are properly acclimatized.

So please don’t be alarmed at mention of things like altitude sickness etc, but rather see this as educating yourself to be able to recognise the signs both in you and in others, which will enable you to make decisions in the best interests of you, and the runners around you.

Of course our brilliant medical support team from ECMR will be watching and checking for signs, and will be on hand to assist in the event you have concerns.


Best course of action a week before the event

  • Get your overall body hydration up to capacity by drinking 3-4l per day
  • Eat well balanced meals, focussing on lots of greens, fruit & nuts to get your body topped up with vitamins and minerals

During the run

  • Make sure you have the right fuels for the job – check out the blog on www.wildrunner.co.za about the Hammer products and how to use them.

After the run

  • Hammer are supplying their famous ‘Recoverite’ for you at the finish.  These will go along way to helping replace what you have lost during the day.
  • Eat well, and keep hydrating once you are finished.
  • Book a massage and help those muscles get rid of the lactic acid build up from having to exert yourself with lower oxygen.

Definitions & explanations:

High Altitude

Altitude is defined on the following scale:

High (8,000 – 12,000 feet [2,438 - 3,658 meters])

Very High (12,000 – 18,000 feet [3,658 - 5,487 meters])

Extremely High (18,000+ feet [5,500+ meters]).


Acute Mountain Sickness (AMS)

Altitude sickness, also known as acute mountain sickness (AMS), altitude illness, hypobaropathy, or soroche, is a pathological effect of high altitude on humans, caused by acute exposure to low partial pressure of oxygen at high altitude. It commonly occurs above 2,438 meters (8,000 feet).

High Altitude Pulmonary Edema (HAPE)

HAPE results from fluid buildup in the lungs. The fluid in the lungs prevents effective oxygen exchange. As the condition becomes more severe, the level of oxygen in the bloodstream decreases, and this can lead to cyanosis, impaired cerebral function, and death. Symptoms include shortness of breath even at rest, “tightness in the chest,” marked fatigue, a feeling of impending suffocation at night, weakness, and a persistent productive cough bringing up white, watery, or frothy fluid. Confusion, and irrational behavior are signs that insufficient oxygen is reaching the brain. One of the methods for testing yourself for HAPE is to check your recovery time after exertion. If your heart and breathing rates normally slow down in X seconds after exercise, but at altitude your recovery time is much greater, it may mean fluid is building up in the lungs. In cases of HAPE, immediate descent is a necessary life-saving measure (2,000 – 4,000 feet [610-1,220 meters]). Anyone suffering from HAPE must be evacuated to a medical facility for proper follow-up treatment.


What causes altitude related illnesses?

The concentration of oxygen at sea level is about 21% and the barometric pressure averages 760 mmHg. As altitude increases, the concentration remains the same but the number of oxygen molecules per breath is reduced. At 12,000 feet (3,658 meters) the barometric pressure is only 483 mmHg, so there are roughly 40% fewer oxygen molecules per breath. In order to properly oxygenate the body, your breathing rate (even while at rest) has to increase. This extra ventilation increases the oxygen content in the blood, but not to sea level concentrations. Since the amount of oxygen required for activity is the same, the body must adjust to having less oxygen. In addition, for reasons not entirely understood, high altitude and lower air pressure causes fluid to leak from the capillaries which can cause fluid build-up in both the lungs and the brain. Continuing to higher altitudes without proper acclimatization can lead to potentially serious, even life-threatening illnesses.


Symptoms of mild AMS

Headache, dizziness, fatigue, shortness of breath, loss of appetite, nausea, disturbed sleep, and a general feeling of malaise. Symptoms tend to be worse at night and when respiratory drive is decreased.


Basic treatment of mild AMS

The symptoms of Mild AMS can be treated with pain medications for headache and Diamox. Both help to reduce the severity of the symptoms, but remember, reducing the symptoms is not curing the problem. Diamox allows you to breathe faster so that you metabolize more oxygen, thereby minimizing the symptoms caused by poor oxygenation. This is especially helpful at night when respiratory drive is decreased. Since it takes a while for Diamox to have an effect, it is advisable to start taking it 24 hours before you go to altitude


Moderate AMS

Moderate AMS includes severe headache that is not relieved by medication, nausea and vomiting, increasing weakness and fatigue, shortness of breath, and decreased coordination (ataxia). Normal activity is difficult, although the person may still be able to walk on their own. At this stage, only advanced medications or descent can reverse the problem.


Prevention of Altitude Illnesses

Prevention of altitude illnesses falls into two categories, proper acclimatization and preventive medications. Below are a few basic guidelines for proper acclimatization.

  • If possible, don’t fly or drive to high altitude. Start below 10,000 feet (3,048 meters) and move up.
  • If you do fly or drive into high altitude, do not over-exert yourself or move higher for the first 24 hours.
  • If you go above 10,000 feet (3,048 meters), only increase your altitude by 1,000 feet (305 meters) per day and for every 3,000 feet (915 meters) of elevation gained, take a rest day.
  • “Climb High and sleep low.” This is the maxim used by climbers. You can climb more than 1,000 feet (305 meters) in a day as long as you come back down and sleep at a lower altitude.
  • If you begin to show symptoms of moderate altitude illness, don’t go higher until symptoms decrease (“Don’t go up until symptoms go down”).
  • If symptoms increase, go down, down, down!
  • Stay properly hydrated. Acclimatization is often accompanied by fluid loss, so you need to drink lots of fluids to remain properly hydrated (at least 3l per day). Urine output should be copious and clear.
  • Take it easy; don’t over-exert yourself when you first get up to altitude. Light activity during the day is better than sleeping because respiration decreases during sleep, exacerbating the symptoms.
  • Avoid tobacco and alcohol and other depressant drugs including, barbiturates, tranquilizers, and sleeping pills. These depressants further decrease the respiratory drive during sleep resulting in a worsening of the symptoms.
  • Eat a high carbohydrate diet (more than 70% of your calories from carbohydrates) while at altitude.
  • The acclimatization process is inhibited by dehydration, over-exertion, and alcohol and other depressant drugs.


Preventive Medications

Diamox (Acetazolamide) allows you to breathe faster so that you metabolize more oxygen, thereby minimizing the symptoms caused by poor oxygenation. This is especially helpful at night when respiratory drive is decreased. Since it takes a while for Diamox to have an effect, it is advisable to start taking it 24 hours before you go to altitude and continue for at least five days at higher altitude. The recommendation of the Himalayan Rescue Association Medical Clinic is 125 mg. twice a day (morning and night). (The standard dose was 250 mg., but their research showed no difference for most people with the lower dose, although some individuals may need 250 mg.) Possible side effects include tingling of the lips and finger tips, blurring of vision, and alteration of taste. These side effects may be reduced with the 125 mg. dose. Side effects subside when the drug is stopped. Contact your physician for a prescription. Since Diamox is a sulfonamide drug, people who are allergic to sulfa drugs should not take Diamox.Diamox has also been known to cause severe allergic reactions to people with no previous history of Diamox or sulfa allergies. It is recommends to take a trial course of the drug before going to a remote location where a severe allergic reaction could prove difficult to treat.


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Tags: altitude, diamox, hydration, mountain, running, sickness

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