Altitude Training – Does it Work?
By: PhD Hans Kristian Stadheim – Coach and Exercise Physiologist
This article addresses altitude training and physical performance capacity. Several athletes who are currently part of Team Aker Dæhlie (TAD) have tested or are using altitude training in an attempt to optimize their physical performance. But does altitude training actually work?
First of all, it is important to emphasize that in all forms of training there are nuances. There are large individual variations in how different training stimuli affect each athlete. The same applies to altitude training. Consequently, athletes who aim to live off their sport and call themselves elite athletes should choose training methods that represent “best practice” for development. From the best athletes we know that they are often open and curious about training elements that can potentially make them a few percent better. However, it is not always the case that newly implemented training interventions lead to improvements.
The purpose of this article is therefore to shed light on altitude training from a professional perspective, and to highlight both potential benefits and drawbacks as objectively as possible. Nevertheless, it is important to clarify that this article is not a concrete manual. The advice cannot guarantee that you will personally achieve an optimal altitude training camp, but it may be helpful. Hopefully, this article can be useful for athletes considering implementing altitude training into their training program.
Silje Theodorsen, Font Romeu 2025
What is altitude, and what happens?
During the 1968 Summer Olympics in Mexico City, which is located about 2250 meters above sea level, it became clear that something happened when athletes arrived to compete. At that Olympic Games, African runners from highland regions won all distances over 800 m, while favorites such as Australian Ron Clarke experienced severe breathing problems and collapsed. There may be several reasons why the African runners performed remarkably well at this altitude. Nevertheless, after the championship, attention turned toward the importance of altitude acclimatization, and research into altitude training as preparation for competitions began.
More recently, we saw the same phenomenon during the Beijing 2022 Winter Olympics. Here, athletes from nations that had prioritized altitude training in the years leading up to the event (e.g., Finland and Russia) won a relatively larger share of the cross-country skiing medals. Everyone involved in elite sport understands that many factors influence the final results at a championship. Despite this, the question remains: what actually happens when you go to altitude that could explain performance being affected to such a degree that altitude training might be necessary? In addition, are there other potential benefits of prioritizing altitude camps with respect to performance at sea level?
Altitude and performance
As you move “higher into the terrain,” barometric pressure drops. In other words, the distance between O₂ molecules becomes greater, which means there is “less oxygen.” Technically, this statement is incorrect, as the percentage of oxygen in the air is the same at 8000 m as at sea level (20.9%), but the pressure (partial pressure) is lower. So how does this reduced pressure affect the body, and why is it harder to train and compete at altitude?
This is where the “magic” of altitude training and acclimatization lies. It involves the process by which oxygen molecules diffuse from the lungs, bind to red blood cells (hemoglobin), are delivered to the working muscles, and carbon dioxide (CO₂) is transported back to the lungs.
Pressure differences drive gas exchange in the body. At high altitude, these gradients are significantly reduced. (See figure in: https://sml.snl.no/h%C3%B8ydefysiologi_og_h%C3%B8ydeakklimatisering)
Lungs, oxygen uptake, and CO₂ removal
All gases in the human body move from areas of high to low pressure. For example, there is more O₂ in arterial blood than in muscles, which is why O₂ diffuses from red blood cells into the muscles during activity. Conversely, CO₂ produced during metabolism moves in the opposite direction, from the muscles into the blood, to be exhaled by the lungs.
At altitude, the problem is that the pressure difference between the surrounding air and the alveoli (the small sacs in the lungs where gas exchange occurs) is lower than at sea level. This makes it harder for the lungs to fully saturate the blood with oxygen. At sea level, even during intense exertion, blood oxygen saturation remains above 95%. At 2000 m, however, some individuals may have as little as 85–90% oxygen saturation at rest. During activity, this may drop to 80–85%, with large individual differences compared to sea-level activity.
It doesn’t take a PhD in exercise physiology to understand that when there is 10–15% less oxygen available in the blood, both performance and recovery capacity are significantly reduced. Acutely, during endurance training (at and below threshold), the physiological response is that the heart and lungs must work harder (higher frequency) to meet the energy demand (VO₂) because of the reduced oxygen content in the blood. Thus, the lower partial pressure of oxygen is the main cause of most physiological changes at altitude.
Dehydration
Increased ventilation and heart rate at altitude also lead to another physiological challenge: dehydration. More water vapor is lost through exhaled air, and the higher metabolic rate demands more fluid. Changes also occur in metabolism, hormone balance, acid-base regulation, brain function, and sleep regulation, all of which are important for a successful altitude camp or acclimatization process.
For example, reduced sleep quality directly affects day-to-day recovery. Combined with lower temperatures at altitude, this can further increase fluid loss. A good rule of thumb is to increase fluid intake, either with water plus a pinch of salt or sports drinks containing electrolytes to retain fluid more effectively. Clear urine is not always a sign of proper hydration, as it does not indicate whether the fluid has been bound in the body, though it is still preferable to dark urine. Carbohydrates also help retain fluid, making carbohydrate intake especially important during the first phase of an altitude camp.
Why train at altitude?
One often overlooked effect of altitude is that it serves as an excellent learning arena to practice how to best plan and execute a competition at altitude. The literature does not fully agree that altitude is necessary for optimal sea-level performance. However, scientific consensus suggests that it is crucial for competitions at altitude (everything above 500 m).
Reduction in VO2max (Performance) during acute exposure to different altitudes
Adaptation to altitude takes time and requires doing things correctly. Even if training is perfect, results may still be disappointing if the athlete does not learn how to strategically approach competition at altitude. Pacing, tactical decisions, and technique are all more critical. Mistakes at altitude—overtraining, underhydration, poor recovery—are punished more severely than at sea level.
So why would someone choose altitude training if the risks are higher and no competition at altitude is planned? Two main arguments exist:
Altitude often offers good training conditions, better weather, and beautiful surroundings, especially in late autumn. New environments can also provide renewed motivation and focus. Camps foster team bonding and provide an environment with meals and fewer distractions, which may enhance training quality.
The so-called “altitude effect”: longer stays at altitude can stimulate physiological adaptations due to reduced oxygen saturation. This typically triggers increased production of red blood cells (erythrocytes), leading to higher total hemoglobin mass (Hbmass). Many studies show this improves oxygen transport capacity and endurance performance. However, if the camp is poorly executed, or if the athlete is a so-called “non-responder,” Hbmass and performance may even decrease.
Relationship between total Hb mass and VO2max.
Some keys to a successful altitude camp
Minimum 17–24 days (“3 weeks”) at altitude.
Live above 1800 m, with 17–24 hours/day spent in hypoxia.
Shorter stays or fewer hours in hypoxia yield little to no effect.
Successful altitude training can also cause adaptations at the genetic level, in pH balance, and in mitochondria (Gore et al., 2006).
Typical increase in Hbmass: 4–6% (https://www.ncbi.nlm.nih.gov/pubmed/27343108).
Some studies show no altitude effect, leading some to argue that the benefits may also stem from stricter focus on training, nutrition, and recovery during camps.
Ultimately, success depends on precise management of training load and total stress. Many athletes have failed here, and therefore concluded that altitude training “doesn’t work.”
Increase in HBmass with different durations at altitude
Tips and tricks for athletes going to altitude
It is generally an advantage to already have a high endurance level.
There is nothing wrong with trying altitude training for the experience, but systematic altitude training should mainly be used by athletes at a high level.
Rough training structure at altitude
Day 1–5: Very easy training, possibly one light interval (Day 5, Zone 2/3).
Day 5–10: Gradual progression (Day 10, controlled Zone 3 interval).
Day 10–15: Normalized load (Day 12 and 15, Zone 3).
Day 15–24: Training more similar to sea level (can attempt Zone 3–4).
Day 24–28: Reduce training load to avoid illness before traveling home.
Note: Load should vary within the aerobic range. Monotonous training or too high intensity has even more negative consequences at altitude than at sea level.
Heart rate and pulse
Anaerobic threshold heart rate is reduced by ~3–5 beats per 1000 m during the first week, stabilizing at 1–3 beats below normal after a week.
Max heart rate decreases by ~3–4 beats per 1000 m in the first week, then by ~2–3 beats. (https://www.ncbi.nlm.nih.gov/pubmed/16311764)
Recommendation: Train at ~10 beats lower than normal zones during the first 5–7 days.
If lactate measurement is available, use it to fine-tune intensities, since individual variation is significant.
Recommended reading
Finally, here are a few articles that may be interesting and scientifically solid. I have tried to highlight both positive and negative aspects of altitude training, as suggested by the title of this post. As you can see, it is important to take it easy at altitude and consult with experienced professionals.
Individual respons - https://onlinelibrary.wiley.com/doi/abs/10.1111/sms.13804
Heat versus altitude - https://journals.lww.com/acsm-essr/fulltext/2021/01000/heat_versus_altitude_training_for_endurance.7.aspx
Sleep wuality and altitude - https://www.sciencedirect.com/science/article/pii/S2352721821001765
Hbmass and VO2max - https://bjsm.bmj.com/content/47/Suppl_1/i26.short
Hbmass and VO2max - https://www.sciencedirect.com/science/article/abs/pii/S144024409880011X
Hbmass and VO2max - https://onlinelibrary.wiley.com/doi/abs/10.1111/sms.14218
Conclusion
Altitude training can be an effective tool to enhance performance, but only if done correctly and tailored to the individual’s needs. It can trigger physiological adaptations that improve endurance, yet the risk of reduced performance is high if the camp is not carefully planned.
Large individual differences - not everyone responds positively.
Reduced oxygen pressure → lower O₂ saturation, higher heart rate, greater strain.
Dehydration and sleep disturbances are common challenges.
Duration is critical: at least 17–24 days above 1800 m.
Careful control of training intensity and overall load = essential.
Most relevant for athletes at a high level with a solid training base.
Potential benefits: increased Hb mass (4–6%), improved endurance + mental advantages (team bonding, focus, motivation).
Altitude training can provide a clear performance boost – but only for those who plan well, tolerate the stress, and adapt to their body’s response.
References
Gore, C. J., Clark, S. A., & Saunders, P. U. (2007). Nonhematological mechanisms of improved sea-level performance after hypoxic exposure. Medicine and Science in Sports and Exercise, 39(9), 1600–1609. https://doi.org/10.1249/mss.0b013e3180de49d3
Heinicke, K., Heinicke, I., Schmidt, W., & Wolfarth, B. (2005). A three-week traditional altitude training increases hemoglobin mass and red cell volume in elite biathlon athletes. International Journal of Sports Medicine, 26(5), 350–355. https://pubmed.ncbi.nlm.nih.gov/15925734/
Levine, B. D., & Stray-Gundersen, J. (1997). “Living high-training low”: Effect of moderate-altitude acclimatization with low-altitude training on performance. Journal of Applied Physiology, 83(1), 102–112. https://doi.org/10.1152/jappl.1997.83.1.102
Lundby, C., Robach, P., & Saltin, B. (2012). The evolving science of altitude training for endurance performance enhancement. Experimental Physiology, 97(3), 259–266. https://doi.org/10.1113/expphysiol.2011.062838
Schuler, B., Thomsen, J. J., Gassmann, M., et al. (2007). Timing the arrival at 2340 m altitude for aerobic performance. Scandinavian Journal of Medicine & Science in Sports, 17(5), 588–594. https://pubmed.ncbi.nlm.nih.gov/16311764/
Wehrlin, J. P., & Hallén, J. (2006). Linear decrease in VO2max and performance with increasing altitude in endurance athletes. European Journal of Applied Physiology, 96(4), 404–412. https://doi.org/10.1007/s00421-005-0081-9
Schmidt, W., & Prommer, N. (2008). The optimised CO-rebreathing method: A new tool to determine total haemoglobin mass routinely. European Journal of Applied Physiology, 95(5–6), 486–495. https://pubmed.ncbi.nlm.nih.gov/27343108
Store medisinske leksikon. (u.å.). Høydefysiologi og høydeakklimatisering. Hentet fra https://sml.snl.no/h%C3%B8ydefysiologi_og_h%C3%B8ydeakklimatisering
Wilber, R. L. (2007). Altitude Training and Athletic Performance. Human Kinetics. https://link.springer.com/chapter/10.1007/978-1-4899-7678-9_24
Schmidt, W., & Prommer, N. (2018). Impact of alterations in total hemoglobin mass on VO2max. Frontiers in Physiology, 9, 319. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5871736/