Updated: Apr 26, 2022
Over the past few years I have had the opportunity to Race Across the Sky in the Leadville 100 MTB and the 3 day-Breck Epic. Each of these races start above 9500ft. Are you racing or considering racing at altitude? Here are a few things I learned and that should be considered. Much of my research was talking to other coaches and athletes about their experience and from “Altitude Training and Athletic Performance” by Dr. Randal Wilber. It can be found on Amazon if you want to learn more.
First, let’s discuss what happens to the air as altitude increases. The amount of oxygen in the atmosphere is 20.9%. This is uniform across the globe. However, atmospheric pressure is impacted by altitude. As you gain altitude, atmospheric pressure is reduced, which influences the effective oxygen. For example, Boston, at sea level, has an effective oxygen of 20.9%, but the town of Leadville, CO has effective oxygen of 14.3%. This translates to 31.5% less oxygen per breath because of the atmospheric pressure.
So, what does this mean? Because of reduced air pressure at higher altitudes, oxygen diffuses into your red blood cells slower, meaning that your blood receives less oxygen as it passes through your lungs, reducing blood oxygenation to the muscles. The body’s natural response to the lower oxygen to your muscles is to increase the heart rate to bring in more oxygen. This can translate to reaching your max output faster, making it harder to recover from max efforts.
There are a few things that typically happen at altitude:
VO2max starts to decrease at 5000ft. At 7544ft, VO2max is decreased by 15% for elite runners. During the Leadville 100, VO2max could drop by 15-20%.
There could also be a loss of appetite and increase chance of dehydration.
Sleep and mental performance can also be negatively impacted. The quantity and quality of sleep can be diminished. Mental performance can also be impacted (i.e. doing simple math at 12,000ft. can be challenging).
While no two people are the same and your body may react differently each time, here are three things that you should consider to maximize your performance at altitude:
Acclimation: Ideally athletes should allow for an acclimation period. The time for the body to adapt to altitude varies with the individual and with both the altitude ascended and the speed of ascent. A typical acclimatization period lasts for 2-3 weeks. During this acclimation period, the body produces more red blood cells. The additional red blood cells allow for more oxygen to be carried to the muscles. While everyone is different, I have personally found that if I cannot be at altitude for 2-3 weeks, arriving right before the race works better than being there for a week or so. Again, everyone is different. (Here are more details on acclimatization.) There is also an option to acclimate at home with an altitude tent which is used to simulate a higher altitude. The basic concept of living or training at altitude is to force the body to adapt to the lower oxygen content by producing more oxygen-carrying red blood cells and hemoglobin. Training or spending time at a higher altitude will enable this, potentially providing enhanced performance.
Hydration: Hydrating while at altitude is equally important as you are likely losing body water through increased urination and breathing combined with a decreased water intake. I have found that additional water and electrolytes have helped.
Nutrition: This is also key. You could have a reduced appetite at higher altitudes, thus it is important that you are getting enough quality calories. Studies have shown that a small increase in carbohydrates can help adapting to and performing at higher altitudes.
Understanding the symptoms of altitude sickness can save your life. Learn more about the symptoms and treatment here. The bottom line is, when racing at altitude be aware of your body, understand the potential effects and manage them the best you can. Enjoy the experience and be safe!