Altitude Sickness: HAPE and HACE

We all feel it. The light-headedness. Can hardly breathe. Slow onset headache.

Living at roughly 4800 feet definitely has its benefits. However, many of us seek elevations greater than this. With significant and sudden gains, altitude sickness can set in. We know it is due to the higher elevation and the drop in oxygen, but what is really going on?

There are two primary forms of altitude sickness:

  1. High Altitude Pulmonary Edema (HAPE)
  2. High Altitude Cerebral Edema (HACE)

HAPE is fluid accumulation in lungs that causes the obvious symptom of breathlessness (with exercise and when at rest). HAPE can be deadly especially when the breathlessness progresses to an elevated body temperature and coughing.

HACE is fluid accumulation in the brain causing headache, dizziness, confusion, and clumsiness. Drowsiness and loss of consciousness are a major indication that HACE has reached a deadly level.

HAPE and HACE often occur simultaneously, and again, can be very serious. Once symptoms start, they will progressively worsen and can eventually lead to death.

In the case of HAPE and HACE, immediate descent is the first course of action. Supplemental oxygen can be helpful in relieving symptoms and will essentially “buy time”.

A prescription drug for altitude sickness does exist - Diamox (this is the brand name). The active ingredient is Dexamethasone which prevents swelling in the brain and subsequently reduced symptoms. It is recommended that Diamox be taken several days prior to being at altitude as the side effects can be equally as bad and as deadly as the altitude sickness itself and need to be noticed prior to making an ascent.


So what are the training implications when anticipating significant altitude gain?


Ultimately, progressive exposure to higher elevations allows for the body to naturally increase production of red blood cells and oxygen-carrying hemoglobin. This maximizes the body’s capacity to store oxygen and will make exposure to higher altitudes more tolerable.

Within 24-48 hours your body will have already increased its red blood cell production. This is often why when you arrive at camp you may feel the effects of altitude sickness, but after sleeping through the night, the next morning is much better.

Red blood cells have a lifespan of about 120 days. So, when anticipating a high altitude excursion or race, this is your window of opportunity.


They say: “Live high, train low.”


This refers mainly to the use of altitude tents as most of us don’t have the luxury of living at 9,000 feet and training at sea-level. However, remember that 120-day window? There is an opportunity here for those of us who call the mountains home yet would enjoy several weeks of training camp in San Diego!

By “living high”, the body is constantly being stimulated to produce red blood cells to match the oxygen demand of living at altitude.

“Train low” optimizes the additional oxygen-carrying capacity by allowing for increased intensity and volume that would not otherwise be attainable.

So what is the take-home here?

Live in the mountains...

... and train at the beach ;)