Tips for High Altitudes
Healthy in High Country
The following section is an excerpt from Open Your Heart with Winter Fitness by Lisa Marie Mercer.
I Want to Take You Higher
Upon hearing the beck and call of the mountains, many a lowlander has been known to offer a quick response. The lure of skiing in Colorado or trekking the Himalayas holds the promise of unique excitement for sea level city dwellers. Yet lest you be hasty in your travel plans, it behooves you to consider the hazards of high altitude. A trip to High Country need not be dangerous, if rigorous precautions are taken.
How High is High?
Altitude is described by the following scale:
• High: 8,000-12,000 feet
• Very High: 12,000-18,000 feet
• Extremely High: Above 18,000feet
As of yet, no study has been conclusive as to what factors influence a person’s susceptibility to altitude sickness. Men and women of all ages and levels of fitness may or may not be susceptible. To further complicate matters you may take one trip and have no symptoms, than return at a different time and get considerably ill. While most people can travel to 8,000 feet without problem, if you rarely travel above sea level, it’s best to be prudent in your preparations.
All I Need is the Air That I Breath
At sea level, oxygen concentration is at approximately 21% and barometric pressure is at 760mmHG. With the increase in altitude, oxygen concentration is unchanged, but the number of oxygen molecules per breath is significantly reduced. This is due to the fact that at 12,000 feet, barometric pressure is only 483mmHG, thereby giving even the most enthusiastic skier or hiker 40% fewer oxygen molecules per breath. To properly oxygenate the body, your breathing rate must increase. The added ventilation increase oxygen content in the blood, but not to the same concentration it was at sea level.
Unfortunately, whatever activity you are participating in will still require the same amount of oxygen, but your body must adjust to having less of it. High altitude can also cause fluid to leak from the capillaries, which in turn can cause fluid build up in the brain and lungs.
So What’s the Problem?
Persistent increased breathing results in the reduction of carbon dioxide in the blood. Since carbon dioxide build up is the key signal to the brain that it is time to breathe. If levels are low, the drive to breathe is inhibited. If you are awake it isn't much trouble to consciously breathe. At night an odd breathing pattern develops due to an alternating balancing act between two respiratory triggers. This periodic breathing consists of cycles of normal breathing which gradually slows, followed by 10-15 seconds of breath holding breath-holding, and a brief recovery period of accelerated breathing. This is not considered altitude sickness. However, while it usually improves with acclimatization, it rarely resolves till descent from altitude. Periodic breathing can be the cause of anxiety in a person who wakes up during the breath holding phase, or in someone who awakens during the accelerated breathing phase, believing that they are suffering from an extreme form of high altitude sickness.
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