The Pros and Cons of Altitude Training Camps

By Jim Rutberg,
CTS Pro Coach, co-author of “The Time Crunched Cyclist” and “Training Essentials for Ultrarunning”

Athletes use altitude training camps to stimulate the production of red blood cells, thereby increasing the oxygen carrying capacity of their blood. There are other benefits, too, but the increase in red blood cells is the most familiar. However, training at altitude can have significant drawbacks. Mistakes with altitude training can hurt performance more than help it. To determine whether an altitude training camp is a good idea for you, let’s look at the rationale behind them, as well as the risks and potential benefits associated with training at altitude.

What is an altitude training camp (ATC)?

An altitude training camp is when an athlete or team spends a chunk of time training, and presumably living and sleeping, at elevations higher than about 6,000 feet above sea level. Some ATCs are short, just a few days, and others last three weeks or more. As I’ll describe later, there’s a big difference in the goals and outcomes of ATCs of varying durations.

Athletes at most ATCs train, live, and sleep at elevations between 6,000 and 9,000 feet above sea level for the duration of the camp. Some locations – including Woodland Park-to-Colorado Springs and Flagstaff-to-Phoenix – offer the option to live and sleep at altitude, then descend and train at elevations thousands of feet lower. This method is known as “Live High, Train Low”.

Still another option for ATCs involves living, sleeping, and training at altitude, but incorporates supplemental oxygen during some specific high-intensity interval sessions.

How altitude affects endurance performance

The basics of altitude work like this: as you go higher the air becomes less dense, which means the oxygen molecules are more spread out. As a result, when you breathe in and fill your lungs, there are fewer oxygen molecules in that volume of air.

Most people from sea level don’t notice any difference at elevations up to about 5,000 feet above sea level. Between 5,000 and 8,000 feet, most healthy people feel perfectly fine at rest. They might get out of breath more quickly while exercising. The impact of “moderate” elevation is relatively minor because your lungs are very good at extracting oxygen from air. You’re still able to satisfy the body’s needs, even as the air gets thinner.

Once you get above about 8,000 feet, things are a bit different. At these higher elevations people who normally live at sea level get out of breath just walking up a flight of stairs. Your heart rate and breathing rates at rest will be slightly elevated as your body tries to pull more air through the lungs so it can grab the oxygen it wants.

When you exercise at altitude, you reach your maximum sustainable pace or intensity level much more quickly than at sea level. This means that if your lactate threshold power is 250 watts at sea level, at 8,000 feet above sea level you’ll likely reach lactate threshold at about 225 watts (a 10% decline). You’ll be slower riding uphill, or you’ll need to push yourself harder than normal to achieve the same speed you can hold on a climb at sea level. As you go even higher, your maximum sustainable power will keep dropping, and it will become increasingly difficult to recover from hard efforts above lactate threshold.

How Altitude Training Camps Work

Considering how detrimental altitude is to endurance performance, why would any athlete choose to do an ATC? Well, because exposure to higher elevations triggers a cascade of changes that help humans adapt to living and exercising in high altitude environments. The most well-known adaptation is an increase in hematocrit, or the volume of red blood cells in your blood.

In the short term, increased relative hematocrit results from a reduction in blood plasma volume. This happens in a matter of days. There’s no change in the number of red blood cells. You just lose plasma volume, which is mostly water. In the long term, altitude exposure leads to increased secretion of your body’s own erythropoietin (EPO), which stimulates increased red blood cell production. This takes a lot longer, a minimum of three weeks and potentially up to six weeks.

For intermittent altitude exposure, whether from a “live high, train low” scenario or a simulated version of it utilizing an altitude tent, the duration of daily altitude exposure matters. The common recommendation is real or simulated altitude exposure for at least 12 hours/day for at least 21 consecutive days. As an example, a 2019 study had subjects spend 12 hours/day at a simulated altitude of 3,000 meters above sea level for 21 consecutive days (Park et al 2019).

How long do the effects of a long altitude camp last?

Let’s say you manage to conduct a three-week altitude training camp and everything goes perfectly. (We’ll talk later about how things can go less-than-perfectly.) You leave your ATC with an elevated hematocrit and travel to sea level for competition or to continue training.

What happens? That depends on the athlete, their cumulative exposures to altitude over a period of months or years, and their post-camp activities. In a 2019 narrative review in Sports Medicine, authors Iñigo Mujika, Avish Sharma, and Trent Stellingwerff included findings that ranged from a few days to several weeks. Some athletes achieved their best post-altitude performances within 3-5 days of returning to sea level. Others performed best about 3-4 weeks after returning to sea level. Like many aspects of training, there appears to be significant individual variability in the decay of altitude camp benefits.

What about short altitude camps?

Many athletes preparing for competitions at altitude participate in short ATCs, typically lasting 2-7 days. These are often reconnaissance trips to pre-ride or pre-run parts of a particular course. The duration of altitude exposure during these ATCs is too short to cause an increase in red blood cell production. So, why bother?

Short ATCs are useful for learning how your body responds to acute altitude exposure. Few athletes have the time to spend 3 weeks living at altitude to achieve the increase in red blood cells. Nor do they have the time for repeated 1-2 week ATCs throughout the season – another method of incrementally achieving the benefits of altitude exposure.

The common scenario for a sea level athlete is to arrive at altitude the day before a competition. This allows them to race before feeling the effects of fatigue and disturbed sleep they may experience after another few days at altitude. Short recon ATCs help athletes adjust their pacing, target power outputs, and rating of perceived exertion (RPE) for efforts at altitude.

The downsides of altitude training camps

If everything goes right, an ATC can lead to an increase in hematocrit, which increases the amount of oxygen athletes can deliver to working muscles. The problem is that lots of things can go wrong. And when they do, athletes may perform worse after an ATC than before it.

Here are some of the ways an ATC can hurt performance more than it helps:

• You can’t train as hard

  Characteristically, the training focus during ATCs is on long, easy endurance rides or runs. Hard interval workouts are generally unproductive in the first 1-2 weeks of an ATC. Athletes can’t achieve the target intensities necessary. Zone 2 aerobic endurance training is the most effective use of time. That’s great during certain parts of the training year but can be a problem when you are trying to build or retain race fitness.

• Recovery is hindered

  Post-workout recovery is slower during an ATC, particularly in the first 1-2 weeks. Even if athletes are diligent about keeping training intensity low, those rides or runs take more out of them than they expect. This recovery response is highly individual, may be affected by iron status, and may be affected by how rested an athlete is before the ATC.

• Sleep quality can decline

  Sleep is the best possible activity for promoting recovery. Both the duration and quality of sleep are important, but many athletes have trouble sleeping at altitude. Although this is highly individual, some people have trouble getting to sleep and staying asleep at altitude. The problem tends to get worse the higher you go.

• Greater potential for dehydration

  Humidity levels are lower at altitude than at sea level. As a result, people lose more fluid through respiration because you must humidify the air you breathe in. Sweat evaporates very quickly. And remember, a reduction in blood plasma volume (mostly water is one of the first responses to altitude exposure. This gradually subsides but can be problematic for athletes early in an ATC.

Final Word

Altitude training camps can be great experiences, but it’s important to remember that athletes aren’t machines. They’re people and they don’t always respond to stimuli exactly the way you expect or hope it will. The longer we coach an athlete, the more we learn about their individual responses to things like temperature, hydration status, specific foods, volume of intensity, recovery periods, and altitude training. The more you know about yourself and the more in tune you are with how your body is adapting to acute stress, the better you’ll be able to adjust your training, recovery, and hydration/nutrition if you choose to plan an altitude camp.

References

Mujika I, Sharma AP, Stellingwerff T. Contemporary Periodization of Altitude Training for Elite Endurance Athletes: A Narrative Review. Sports Med. 2019 Nov;49(11):1651-1669. doi: 10.1007/s40279-019-01165-y. PMID: 31452130.

Park HY, Park W, Lim K. Living High-Training Low for 21 Days Enhances Exercise Economy, Hemodynamic Function, and Exercise Performance of Competitive Runners. J Sports Sci Med. 2019 Aug 1;18(3):427-437. PMID: 31427864; PMCID: PMC6683611.