I live and train in Colorado. Most of my riding takes place at 5,300 feet above sea level, and I occasionally race in the high mountains. Case in point: I’m currently training for the Breck Epic, a six-day mountain bike stage race located in Breckenridge, Colorado, which sits at 9,600 feet above sea level.
Preparing for this race (part of our N1 Challenge series) has helped me focus my attention on several factors that will be important to overcome if I want to have a successful race. First, as a time-crunched athlete, I’ve had to be creative with my training.
The other barrier I’m contending with is the altitude. While you might think I’m acclimatized given where I live, remember that the low point of Breckenridge is still over 9,000 feet and much of the racing takes place well above that, upwards of 12,500 feet on the Continental Divide.
The equation is simple: With increasing elevation comes decreasing oxygen availability. That fact makes it easy to predict that your performance will be impacted when training and racing at higher elevations.
However, the effects on your physiology are not always so straightforward. Individual differences in athletes’ responses to altitude make it difficult to predict just how much impact it will have. Furthermore, the time and money you can invest in various coping strategies will change from athlete to athlete.
Still, there are several general aspects of the effects of altitude that every athlete can address. These will help you get to the start line feeling as prepared as possible, so keep them in mind both in training and during the race.
- There are increased physical demands at higher elevations.
- There are increased nutritional demands at higher elevations.
- The timing of your arrival at altitude can have a major impact on performance.
- If your event is multiple days, recovery between stages is critical.
Demands of exercising at altitude
In Fast Talk episode 151, Trevor Connor and Chris Case discuss, among other topics, the effects of altitude on the body and how to prepare for them, with Lindsay Golich, a sports physiologist from the United States Olympic Committee.
When we’re exposed to altitude, whether in the mountains or in a research setting, humans experience a range of responses. Our lungs work harder as respiration increases and oxygen saturation goes down. The body attempts to correct that, in part, by increasing heart rate, cardiac output, and blood pressure. We see declines in plasma volume and experience diuresis as part of these changes. From an exercise perspective, this all serves to reduce our exercise capacity. 
Nutritional demands also increase considerably. When the body is exposed to higher altitudes, there is usually a suppression in appetite paired with an increase in resting metabolic rate, increased fluid loss, and increased carbohydrate metabolism. That all leads to an increased potential for low energy availability, dehydration, and poor glycogen storage, a trifecta for lackluster performance.
The good thing is, you can address some of these issues ahead of time.
In my case, I’ll start by assessing my iron levels, with bloodwork, to see if I have adequate stores or need to focus on consuming additional sources. These can be either foods containing high levels of iron or a low-dose iron supplement, both of which would help correct any potential issues.
This process takes approximately 8-10 weeks, so plan accordingly for your event if you find the need to boost iron levels.
Next, I will assess my baseline nutritional habits during training to better understand energy availability and my typical carbohydrate intake. Based on that information, I’ll make any necessary corrections to enhance energy intake and carbohydrate intake in July (the month before the event), and especially in August to maximize glycogen stores leading up to the race.
Finally, because of the increased demand of high-elevation efforts, and the fact that air is often less humid at altitude, good hydration practices both on and off the bike are critical. I’ll practice drinking more during longer training rides so I can develop the feel for this increased fluid intake.
Immunity can also be compromised at higher altitudes, and low carbohydrate intake is linked to an increase in immune activation. Pushing the upper limits of carbohydrate consumption in training will make me more comfortable ingesting adequate carbohydrate energy during and after each stage.
Speaking of immunity, how about antioxidants? Yes, I will continue to focus on antioxidant-rich fuel sources instead of antioxidant supplements. In my experience, which is backed by research, the foods will contribute to positive recovery and sleep throughout the week. 
Timing your arrival at altitude
In 2013, a team of researchers compiled sport-specific recommendations for when athletes should arrive to altitude prior to competition. 
The data suggests that the first six days after an athlete arrives at altitude are the hardest ones, while longer stays bring on gradual improvements. 
In my case, since Breck Epic will take place at both moderate and high altitude, depending on the stage, being able to ride well at high altitudes for relatively brief periods of time will be important. Due to the physiological and metabolic changes that occur when we’re exposed to moderate and high altitudes, arriving approximately 50 hours prior to the start of the race would be adequate. 
However, you will need to make your own calculation of when to arrive based on your specific race situation. For example, should you arrive one to two days before a six-day stage race, putting you in the worst possible scenario by the end? Or should you try to arrive 12-14 hours before the race, potentially making the first day a little better?
There is a third option: to stay at altitude (in my case, that would be 9,000 feet) for two weeks before the race to allow the body to acclimatize. This is the most logistically challenging option, but a worthwhile one if it can be accommodated. While “staging” at higher altitudes for sea-level competition appears to decrease sea-level performance, that may not be the case when staging for competition at moderate to high altitudes. 
Whatever your situation, it’s often difficult to decide when to arrive, unless cost (for things like hotels) or time availability (if work/life limits you) makes the choice for you. In any case, having a better understanding of your options and the window of opportunity will help you make the race more manageable.
Recovering between stages
If you’ve targeted a stage race at altitude, you face additional challenges because of the increased need to recover between race days.
There are several strategies you can use to try and maintain performance from day to day.  First, snack frequently on high-carbohydrate foods, aiming for 8-10 grams per kilogram of carbohydrate per day, or around 550-700+ grams per day. I’ll do this by eating plenty of fruits and vegetables.
I’ll also make sure to consume protein after the race to maintain high protein synthesis rates for damaged muscles. Finally, I’ll eat foods high in tryptophan to aid my mood and sleep quality.
Altitude can be overcome
While many athletes are intimidated by racing at altitude, there are significant steps you can take to mitigate the effects, which will not only help your performance but increase your enjoyment. (The feeling of “breathing through a straw” is never fun.)
It’s worth emphasizing that the recommendations above have very little to do with training and everything to do with preparation: knowing the course, travel and logistics, nutrition, and recovery techniques.
While there is much more to the subject of altitude, this overview is an easy reference for the major considerations that will bring you the majority of benefits.
- Khodaee, M., Grothe, H. L., Seyfert, J. H., & VanBaak, K. (2016). Athletes at High Altitude. Sports health, 8(2), 126–132. https://doi.org/10.1177/1941738116630948
- Burtscher, M., Niedermeier, M., Burtscher, J., Pesta, D., Suchy, J., & Strasser, B. (2018). Preparation for Endurance Competitions at Altitude: Physiological, Psychological, Dietary and Coaching Aspects. A Narrative Review. Frontiers in physiology, 9, 1504. https://doi.org/10.3389/fphys.2018.01504
- Chapman RF, Laymon AS, Levine BD. Timing of arrival and pre-acclimatization strategies for the endurance athlete competing at moderate to high altitudes. High Alt Med Biol. 2013 Dec;14(4):319-24. doi: 10.1089/ham.2013.1022. PMID: 24377334.
- Chapman, R. F., Laymon, A. S., & Levine, B. D. (2013). Timing of Arrival and Pre-acclimatization Strategies for the Endurance Athlete Competing at Moderate to High Altitudes. High Altitude Medicine & Biology, 14(4), 319–324. doi:10.1089/ham.2013.1022