Mountain Bike Racing at High Altitude and the Effect on the Body

Breck Epic Training

The Breck Epic races over 12,000ft above sea level multiple times during the 6 day event

If your coach has not prepared you for high altitude bike racing, then knowing the effects of altitude can help you with race day preparation. The effects of high altitude are well known and considerable. After our bodies reach around 7,000 feet above sea level, the saturation of oxyhemoglobin begins to plummet, this is known as hypoxia. While the Breckenridge 100 and Breck Epic race begins at 9600 ft and goes over 12,000 ft at Wheeler Pass, and hits 11,000 ft a few times, you are likely to suffer more than you know. 

When we breathe in air at sea level, the atmospheric pressure of about 14.7 pounds per square inch (1.04 kg. per cm.2) causes oxygen to easily pass through the selectively permeable membranes of the lung, and enter into the blood. At high altitudes, lower atmospheric pressure makes it more difficult for oxygen exchange in the lungs, decreasing muscle oxygen saturation and creating a limitation for utilization.

Effects of Altitude

Most serious racers train at high altitudes to allow for their bodies to acclimate to the decreased atmospheric pressure and free oxygen. During acclimatization, over a few days to weeks, the body produces more red blood cells to compensate for the lower oxygen saturation in the blood at high altitudes. Full adaptation to high altitude is achieved when the production of red blood cells has increased enough to overcome the decreased amount of oxygen even at higher demand state, like during exercise and racing. When this has been achieved the increased production of red blood cells ceases and the body goes back to it normal replacement. This process can take days or even weeks!

What can happen at high elevations if you have not taken the proper precautions and time for acclimation? Altitude sickness. Altitude sickness occurs when you cannot get enough oxygen from the air and your tissues and organs begin to have declining function from the hypoxic state. Early symptoms include: headache, loss of appetite, dehydration, and trouble sleeping. If the body is overtaxed and these symptoms are ignored, people can develop life threatening issues. Having these symptoms can make a long distance bike race a bit more troublesome if one is not prepared. The most common causes is when people who are not used to high altitudes go quickly from lower altitudes to 8000 ft or higher. and don’t give their bodies times to adjust.

Tips for racing at Altitude 

  • First, try to give your body time to acclimate to the race altitude. Go to the race venue a few days or a week or two early so that your body can have the time it needs to compensate for the change in oxygen.
  • Be prepared for a high heart rate as your body will demand for more oxygen. The HR increase is a response to higher oxygen demand.
  • Make sure to ride a few days at altitude during your acclimation period to help encourage the process. This will also help with priming the muscles for exercise and allowing the brain to remind itself of what is going to happen race day. Pain! sweet pain! 
  • Drink plenty of water, staying hydrated will be important. Dehydration can derail anyones race day regardless of altitude or skill level.
  • Avoid alcohol until after the race, but once you drink your fill of water. Stay on top of hydration and nutrition so you do not fall behind.
  • If you do get altitude sickness, get some OXYGEN from the local EMT or hospital. At high altitudes emergency personnel see altitude sickness often. They always have oxygen for supplementation on board!

If you can’t make it to the race venue days in advance, head up the evening or night before. I live in Boise, ID elevation 2730 feet. When I head to Colorado to race, or ride with the boys, the elevation and hypoxia usually hit around day 3-4. On a ride in Crested Butte last summer, I experienced a few days of headache, nausea, and fatigue, and catching up, let alone enjoying the ride, was very difficult. In closing, if you are prepared and plan for your race accordingly, everything should go smooth.

This post is written by Ben Stein, MS, EP-C, at  Ben is currently taking athletes for endurance sport coaching and training.  

Posted in Training Blog.


Head Coach for USAC Certified Cycling Coach.