Altitude training – make the most out of it

Ferenc Soma Kovács, Hungarian national record holder middle-distance runner, NCAA bronze medallist and Harvard-record holder

Jakob Ingebrigtsen, Jessica Hull, Niels Laros, Kristian Blummenfelt, George Mills… What do these world-class endurance athletes have in common?

Beyond belonging to the elite of their respective sports, year after year we find them returning to the same locations: St. Moritz, Font-Romeu, and Sierra Nevada. While most athletes focus on racing during the middle of the summer season, many of the world's best spend weeks away from the spotlight at altitudes of around 2,000 meters.

Given the high accommodation costs and the racing opportunities they sacrifice by doing so, it is fair to ask: why do they keep returning to the same places every year?

The answer is simple: altitude training remains one of the most effective natural performance-enhancing methods available to athletes.

Dr. Zsolt Szakály, professor at Széchenyi István University, aptly described altitude training as an "artificially applied natural training tool." The athlete places the body into an environment to which it must adapt, and that adaptation can ultimately lead to improved performance. This is particularly true in endurance sports, where oxygen uptake and oxygen transport play a decisive role in performance.

But what exactly happens inside the body when we move into the mountains?

Many people assume that there is simply less oxygen in the air at altitude. This is not entirely accurate. The oxygen concentration in the air remains virtually unchanged compared to sea level. What decreases is atmospheric pressure. As a result, each breath delivers less oxygen into the bloodstream—a condition sports scientists refer to as hypoxia.

At around 1,500 meters, most athletes already begin to notice the difference. Heart rate rises, breathing becomes faster, and the same pace suddenly feels much harder. At approximately 3,000 meters, the same workload can require 25–30% more effort than at sea level.

Naturally, the body does not leave this challenge unanswered.

When the kidneys detect reduced oxygen availability, they increase the production of erythropoietin (EPO). One of EPO's primary functions is to stimulate red blood cell production. More red blood cells mean more hemoglobin, and hemoglobin is the molecule responsible for transporting oxygen through the blood.

The more oxygen we can deliver to working muscles, the more effectively we can perform aerobic work.

This is one of the main reasons why the world's best runners, triathletes, and cyclists repeatedly return to altitude training camps.

The effect, however, is not permanent. After returning to sea level, the body gradually returns to normal blood production levels. For this reason, athletes often schedule their most important competitions in the days or weeks following their descent from altitude.

Beyond stimulating red blood cell production, altitude training triggers numerous additional adaptations.

Research suggests that regular altitude exposure can improve the body's ability to absorb and utilize oxygen, which may positively influence VO₂max. VO₂max is one of the most important indicators of aerobic endurance, representing the maximum amount of oxygen the body can take up and utilize during maximal exercise.

Many runners also report that after returning from altitude, breathing feels easier and maintaining the same pace requires less effort. While this sensation is partly subjective, it highlights the remarkable capacity of the human body to adapt to environmental stressors.

This is why altitude camps are not merely a change of scenery. They are a deliberate physiological stimulus that, when applied correctly, can amplify the effects of training.

Now that we understand the primary physiological benefits of altitude training, it is worth examining how to maximize its effectiveness.

Most elite endurance athletes choose altitudes between 1,800 and 2,200 meters, and for good reason. At this elevation, the body receives sufficient hypoxic stimulus to trigger adaptation while training quality can still be largely maintained.

The higher we go, the greater the physiological stress becomes—but the more difficult it is to sustain normal training intensity.

The first few days are challenging for almost everyone. Heart rate may be elevated, sleep quality can deteriorate, headaches may occur, appetite can decrease, and a general sense of fatigue is common. These are mostly natural responses and part of the acclimatization process.

For this reason, the first week is not about heroic training sessions.

Most experts recommend reducing training intensity by approximately 15–20% during the first three to five days and allowing the body time to adjust to the new environment. Training volume can often remain similar, but pace targets should be moderated.

While the first week is primarily about acclimatization, the real adaptations typically become noticeable during the second week. By then, most athletes are sleeping better, resting heart rate stabilizes, and training begins to feel more natural.

The most significant benefits of altitude exposure, however, generally appear around the third week.

This is why the longstanding rule still holds true today: altitude camps shorter than three weeks rarely deliver the full physiological benefits that altitude training can provide.

Altitude affects more than just training—it changes everyday life as well. One of the most important considerations is hydration.

At altitude, the air is typically much drier, while the body loses more fluid due to increased breathing rates. As a result, dehydration can occur much more quickly than at sea level. Most experts recommend increasing daily fluid intake by at least 0.5–1 liter when staying at altitude. This is particularly important during the first few days, when the body has not yet fully adapted to the new environment.

Alongside proper hydration, iron intake becomes equally important. Red blood cell production requires sufficient iron availability. This means that even if the body produces more EPO, the benefits will be limited if iron stores are inadequate. For this reason, many endurance athletes have their ferritin levels tested several weeks before an altitude camp and, when necessary, implement targeted iron supplementation.

Vitamin C can enhance iron absorption, whereas calcium consumed at the same time may reduce it. Therefore, iron and calcium supplements are generally recommended to be taken separately.

In addition to increased fluid and iron intake, recovery becomes critically important.

Altitude exposure itself places significant stress on the body, making sleep even more valuable than usual. Many athletes experience poorer sleep quality during the first few days, waking more frequently or simply feeling less refreshed in the morning. Because of this, it is often wise to dedicate more time to sleep than you normally would at home.

The goal is not necessarily to sleep longer, but rather to provide enough opportunity for the body to obtain sufficient deep sleep and REM sleep. Altitude only delivers its benefits if the body has the opportunity to process and adapt to the stress it receives.

Fortunately, athletes no longer need to rely solely on subjective feelings to determine whether adaptation is occurring.

Polar sports watches can provide particularly valuable feedback during altitude training camps through their recovery and training load metrics. Nightly Recharge allows athletes to monitor how the body is responding to the increased physiological stress, while Cardio Load quantifies the cardiovascular strain imposed by each training session.

This is especially important at altitude because the same workout often creates significantly greater stress than it would at sea level. An easy run or a routine long run may be accompanied by a noticeably higher heart rate, something that Cardio Load immediately detects.

As a result, athletes can see not only how much training they completed, but also how their body responded to that training.

In my own experience, this is particularly useful during the first week, when subjective sensations can often be misleading. A workout may feel relatively easy, while the body is actually dealing with substantial adaptation stress beneath the surface. In these situations, Polar's data can help athletes find the balance between productive adaptation and excessive overload.

Ultimately, altitude training is not magic.

No one becomes a better runner simply by spending three weeks in the mountains. Altitude is merely a tool—one that, when used correctly, can amplify the effects of training.

However, athletes who patiently work through the adaptation process, pay close attention to hydration, iron intake, recovery, and training load management will likely find themselves returning year after year to places like St. Moritz, Font-Romeu, and Sierra Nevada for the same reason the world's best athletes do:

because the investment eventually pays off on race day.

References:

Szakály Zs. (é. n.). Magaslati edzés. Magyar Triatlon Szövetség. https://triatlon.hu/upload/file/dr-szakaly-zsolt-magaslati-edzes.pdf