If you’re typically a sea level dweller traveling to train or race in a high altitude environment may present some unique challenges. Often you will need to pack for cooler temperatures and variable weather conditions, but you will also want to avoid acute mountain sickness (AMS), aka altitude sickness. To combat this, you may want to throw a few extra nutritional items into your backpack.
Some people begin to feel the effects of altitude at around 1,200m or 4,200ft. Others, not until you hit heights like in Vail, Colorado. But once you reach the top of a 14,000-foot high mountain, nearly everyone will be affected by the altitude. Acclimation to the altitude of anything higher than what is normal for you (which, again is an individual response) generally takes anywhere from a few days to a week.
What do you do if your race is on Saturday, but you can’t fly in until Friday? Ensuring you have adequate nutritional needs to compensate for the altitude can be a key factor in staying prepared and ready to go, even when you’re a mile up in the sky. The best practice you can have, and the one factor which has the most scientific backing is that you must increase your hydration. This is due to a variety of physiological changes which occur in the body at higher altitudes. One of the most important things you need to know is that the percentage of oxygen in the air doesn’t change at altitude; there is literally just not as much air. This lack of air pressure can create changes in the plasma volume of blood, in one’s breathing rate, faster heart rate, increased urine output and more. Ensuring that you stay hydrated will hopefully save from the dehydration that can occur at altitude.
Now, whether or not your nutritional intake needs to change is still a bit debated. Within the first few days at altitude, most people tend to see a decrease in weight. This could be due to eating less, or the fact that your body is trying to make up for the lack of oxygen by creating more red blood cells for oxygen delivery to your muscles. This process may naturally, and temporarily, increase your metabolism. Increased metabolism + less food = weight loss (generally). Thus, some researchers argue that you need to increase your calories, and mainly through carbohydrates. Others haven’t found any benefit from added carbs (or negatives!) The good news is everything should level out within a week or so, if you’re there for that long.