Acute Mountain Sickness
by Disa Hatfield

We all know that the city of Denver's nickname is "The Mile-High City." However, at an elevation of 5,280 feet, the fact the city is classified as higher elevation is often overlooked in lieu of the surrounding Rockies (which peak at 14,000+ feet.) Women's Nationals was held in Denver recently, and most of the competitors didn't give a thought to possible side effects of visiting a higher elevation city. Unfortunately, two competitors became quite ill and required medical attention. While their symptoms also could have been attributed to stomach flu or food poisoning, I noticed several visitors and athletes (myself included) complained of minor symptoms such as headaches and general malaise- two primary minor symptoms of acute mountain sickness (AMS).

The cause of AMS is hypoxia, or insufficient oxygen to the tissues. In Denver, the absolute percentage of oxygen in the air is the same as it is at sea level compared to other gasses, but the number of molecules in the specific volume of air is less, meaning less oxygen is available. The primary physiological response to this is an increase in ventilation rate. This in turn can increase water lost through respiration, however, dehydration is usually only a problem with sustained physical activity (such as hiking or skiing). At rest, reduced air pressure and oxygen content actually lead to fluid volume shifts within the intra-and extra-cellular body compartments such that water is actually retained. Only in very severe cases of AMS can these responses become serious, and will usually only occur at elevations of 9,000 feet and above. Minor symptoms of AMS include headache, fatigue, irritability, nausea, sleep disturbances, and indigestion. More severe symptoms included flatulence, bloating, loss of appetite, and vomiting. At higher altitudes, more severe conditions such as cerebral edema and pulmonary edema can occur, however, at Denver's elevation these problems are highly unlikely. Symptoms usually appear 6-12 hours after arrival and peak at 24-48 hours.

So were the athletes at Women's Nationals experiencing AMS? It's quite likely that at least some competitors' symptoms were a result of the altitude. Studies say that anywhere between 10 and 25% of people ascending to elevations only slightly higher than Denver's will experience minor symptoms. Since Denver isn't classified as high altitude (it's only higher altitude), not many studies are done at mile-high elevations. However, AMS symptoms are known to be correlated to how high the elevation actually is. People who are coming from seal level are also at a greater risk for developing AMS, as well as people with pre-existing conditions such as asthma. Laymen articles based on hospital visits put the percentage of Denver tourists exhibiting symptoms of AMS at 20%, so is quite possible that the minor, flu-like symptoms that Denver tourists experience may be AMS.

There is one tried and true way to cure AMS- come back down to sea level. Of course, that's not an option for those of visiting a higher altitude city to compete. There are a few treatments for AMS, but most involve the use of diuretics, which is NOT an option for drug-tested athletes, or supplemental oxygen, which is expensive.

With Bench Nationals being held in Denver in a month, there are a few things competitors can do to decrease the chance of experiencing AMS.
        - Avoid alcohol and sleeping pills, they can decease ventilation rates.
        - Avoid foods high in sodium (usually a given for those athletes trying to make weight anyway).
        - Eat a higher carbohydrate diet a few days before and during your stay and avoid high fat foods (digestion of fatty foods requires oxygen, avoiding them will alleviate some of the indigestion and flatulence problems).
        - Drink plenty of fluids to help maintain fluid regulatory homeostasis.

I realize that most of these suggestions are completely counterintuitive to athletes trying to make weight (and good luck keeping powerlifters away from pizza and the bar). But if you have some of the risk factors for AMS or start to feel a little under the weather when you get there, rest up and follow these guidelines. Good luck to all the competitors traveling to Denver next month, and stay healthy!