Several significant cycling events in August through October of 2021 will take place at elevations higher than 5,000 feet above sea level. Masters Road National Championships are in Albuquerque, New Mexico (5,300 feet above sea level), and events like the Leadville 100 MTB Race, Steamboat Gravel, Breck Epic, and Pikes Peak APEX are all bringing athletes to altitude. MTB National Championships were in Winter Park, Colorado in July and Collegiate MTB National Championship will be in Durango, Colorado in October. Preparing for and coping with altitude’s effects on performance are big concerns for cyclists who don’t live and train at higher elevations, so here is a guide to what you can expect, what you can do to prepare, and how to adjust your behaviors on and off the bike to perform at your best.
The effect of altitude exposure
There isn’t less oxygen in the air at higher elevations (the percentages of oxygen, nitrogen, and carbon dioxide are the same as at sea level) but there is a decrease in air density, which means there are fewer oxygen molecules in a lungful of air. Most people start to feel the effects of elevation at about 5,000-6,000 feet above sea level, and the effects become more pronounced as you go higher. Your body’s initial responses include increases in your breathing rate and heart rate, both at rest and during submaximal exercise.
You start breathing faster and deeper to compensate for the lower partial pressure of oxygen in each lungful of air. And if you’re going to stay at altitude long enough to fully adapt (about three weeks), then this change in respiration is very important. Increased respiration leads you to exhale more CO2, which reduces the pH of blood and stimulates the kidneys to increase urine output. The increase in urine output reduces plasma volume and results in hemoconcentration – or more oxygen-carrying hemoglobin in a given volume of blood. These are temporary solutions. The long-term solution is for the kidneys to produce and release more erythropoietin to increase production of red blood cells.
What to expect when exercising at altitude
Most athletes who travel to compete at altitude are not able to arrive early enough to acclimate completely, and even athletes who live at altitude suffer some detriment to performance. Although there is some variation in the extent to which individual athlete performances are affected by altitude, here is generally what you can expect:
- Sustainable power at lactate threshold will decline by about 10% compared to sea level at altitudes above 6,000 feet. There will most likely be more of a decline as you go even higher, especially above 9,000 feet.
- Heart rate response is likely to be elevated at a given perceived exertion or power output, at least in the early days when you are fresh.
- Recovery from hard efforts will take longer than at sea level and you may need to slow down more substantially.
- The ability to repeat hard efforts will likely diminish.
- You will be more vulnerable to dehydration (on and off the bike) because of the dry air. A headache is one of the first ways people new to altitude realize they are getting dehydrated.
Off the bike you may experience a headache and disturbed sleep. Because of the lower humidity you will lose more fluid to respiration and sweating. Consume more water to stay hydrated, and if you normally consume caffeinated drinks continue to do so. On the other hand, consuming alcohol can contribute to dehydration, headaches, and disturbed sleep, so save the beer for the post-race party.
How to prepare for riding and racing at altitude
The best things you can do to maximize performance during short visits to altitude (like a single race weekend) are maximize your fitness and go to the event well rested. Altitude is going to reduce everyone’s performance capacity by a certain percentage, so you want to be super fit and super rested so your remaining capacity after the reduction is as high as possible.
What about altitude tents and altitude camps?
There are numerous techniques available for simulating altitude exposure or spending time at altitude for acclimation. They can work, but they are often impractical for cyclists who lead busy lives and have careers and families. Perhaps more important, the effects of sleeping in an altitude tent or spending a few weeks at altitude are highly individual and may not deliver the results an athlete expects. In many cases, the costs of reduced training capacity, reduced workout quality, and reduced sleep quality outweigh the potential benefits of increased oxygen-carrying capacity.
Performing your best at altitude
If you are traveling to a moderate- to high-altitude event and don’t have time to completely acclimate, here’s what you can and should do to maximize your race-day performance:
- Arrive either 5-7 days before the start or the day before the start. The reason that arriving 2-4 days before your event isn’t ideal is because that’s when athletes tend to feel the most fatigued. When you arrive the day before, you’re fresh and not yet as affected by sleep disturbance or dehydration. After being at altitude for 4-5 days, athletes often start to feel better because they have completed some of the short-term adaptations, managed their hydration status, and gotten some rest.
- Rely on perceived exertion for pacing. Because of the individual variability in responses to altitude, it is difficult to accurately predict how to adjust your goal power outputs or heart rates. In particular, heart rate will not be a good gauge of intensity, as it is affected by altitude exposure, heat, hydration status, fatigue, and excitement. Although you’ll want to monitor both power and heart rate, perceived exertion will be the most accurate gauge of intensity if you’re unaccustomed to or not acclimated to altitude. While perceived exertion is low tech, it is remarkably accurate.
Fitness, rest, hydration, and conservative pacing are the four key elements to maximizing performance at altitude for athletes who are traveling to higher elevations for a race weekend or week-long cycling trip. While there are more complex strategies available, they also come with the potential for more complications that can hinder recovery, reduce training quality, and ultimately limit performance.
References:
Saunders, Philo U., et al. “Special Environments: Altitude and Heat.” International Journal of Sport Nutrition and Exercise Metabolism, vol. 29, no. 2, 2019, pp. 210–219., doi:10.1123/ijsnem.2018-0256.
