As a UESCA-certified running coach, I work with athletes across the spectrum—from seasoned competitors and elite runners to beginners just starting their journey with jogging and walk/run intervals.
No matter their level, most runners share a common goal: becoming faster, stronger, and more efficient. One proven method to support that goal is running at altitude—a training practice long embraced by elite and Olympic-level endurance athletes for its powerful performance benefits.
High-altitude training offers a range of cardiovascular and physiological adaptations that can enhance aerobic capacity, increase VO₂ max, and improve efficiency when returning to lower elevations.
This is why many professional training camps are based in high-altitude hubs like Boulder, Colorado, and Flagstaff, Arizona, as well as across elevated regions in Africa, Europe, and the U.S.
In this guide, we’ll explore what qualifies as high-altitude training, the key physiological changes it triggers, how those adaptations improve endurance performance, and practical tips for training effectively at elevation.
Understanding Elevation: When Altitude Starts to Impact Performance
If you have ever been to the Swiss Alps, Flagstaff, Arizona, Mexico City, or any other high-elevation area, you might be familiar with the phenomenon of feeling relatively breathless even at a slow walking pace.
In fact, you don’t have to be in the Himalayan mountain range, scaling the Matterhorn, or crossing off one of the 14,000-foot mountains in Colorado to experience the effects of higher elevation.
Particularly if you live at sea level or close to it, even a “moderate elevation“ such as 6,000 feet above sea level can feel notably different from a respiratory and cardiovascular standpoint.
That said, in most cases, runners and other endurance athletes who practice high-altitude training go to locations that are at least 7,000 to 8,000 feet above sea level and often up to 10,000 to 12,000 feet above sea level.
Sports science technology has also enabled endurance athletes to leverage the benefits of altitude training through the “live high, train low“ approach by utilizing altitude training tents.
Some runners may also practice the reverse: “live low, train high, “ in which they might use an altitude training mask for training runs to simulate the limited oxygen availability of high-altitude training conditions.
Less Air, More Effort: How Altitude Impacts Your Breathing and Race Times
Spending time training at higher elevations leads to physiological adaptations in the cardiovascular system. This is because the amount of available oxygen in the air decreases the higher you get relative to sea level.
A common misconception is that there is less oxygen in the air at higher elevations.
However, all atmospheric air contains 21% oxygen, regardless of whether you are at sea level or 60,00 feet above sea level, 10,000 feet above sea level, or even 15,000 feet above sea level.1Physiology. (n.d.). Institute for Altitude Medicine. Retrieved January 15, 2024, from https://www.highaltitudedoctor.org/physiology#:~:text=The%20percent%20of%20oxygen%20is
That said, the available oxygen that you can breathe in with each breath at altitude decreases significantly because there is less air pressure the higher you get above sea level.
Essentially, while the amount of oxygen in the air remains the same at any elevation—21%—this 21% results in less oxygen when there is less air pressure (as there is the higher the altitude). At sea level, the barometric pressure is 760 mmHg, and at 10,000 ft, the barometric pressure is only 534 mmHg.
This lower air pressure results in the equivalent of breathing air with only 15% oxygen at sea level, instead of 21%, which feels like 29% less oxygen in the air at 10,000 feet of elevation compared to sea level.
Air pressure continues to drop as elevation increases. Thus, you have to breathe deeper and faster at high altitudes to take in the same net amount of oxygen that you can breathe in at sea level.
After you’ve adapted, the effort to breathe will feel comparatively easy when you go back to running and racing at sea level.
This will allow you to run faster without being breathless (pushing your anaerobic threshold to faster paces), improving performance.
What to Expect When You First Start Running at Altitude
As explained, one of the main challenges of training at higher elevations versus lower altitudes or sea level is that much less oxygen is available at higher elevations.
Ultimately, this lack of oxygen induces the physiological changes seen after acclimating to high-altitude training.
However, before your body has adapted to having less oxygen at higher altitudes, you can experience side effects of higher elevations.
When there is less oxygen available in the atmosphere, your heart and lungs must work much harder to extract oxygen from the air and then deliver that oxygen to your body.
For this reason, you can experience a rapid heart rate, difficulty breathing, or a faster breathing rate, and other cardiovascular challenges when you first experience higher elevations before acclimating.
This is why it is always recommended to slow down your running pace or physical exertion level for your first several high-altitude runs.
Once you seem to be in the clear of dealing with acute mountain sickness or altitude sickness, you can start trying to pick up your pace and follow your regular training plan as your body adapts to the effects of altitude.
Still, keep in mind that the acclimatization process for high altitude training can take several weeks, so if you are struggling to hit your normal training paces as dictated on your training plan, know that it is okay to slow down and give your body time to adapt to high altitude fully.
As a result, many running coaches recommend training by heart rate when you first start high-altitude running rather than training by pace.
It is entirely normal to experience an elevated heart rate when you first start running at altitude vs sea level, so you can use your heart rate to help guide your physiological exertion level and your body’s tolerance to the lower amount of oxygen and changes in air pressure at higher elevations.
What Are The Benefits Of High-Altitude Training?
So, how exactly does subjecting your body to less oxygen improve performance?
- Increasing your aerobic capacity (VO2 max) and aerobic endurance at sea level because oxygen delivery and extraction improve as the body works harder to make do with less oxygen coming in.2Levine, 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
- Increasing the production of erythropoietin,3Park, H., Hwang, H., Park, J., Lee, S., & Lim, K. (2016). The effects of altitude/hypoxic training on oxygen delivery capacity of the blood and aerobic exercise capacity in elite athletes – a metaanalysis. Journal of Exercise Nutrition & Biochemistry, 20(1), 15–22. https://doi.org/10.20463/jenb.2016.03.20.1.3 the protein that stimulates the production of red blood cells. Red blood cells carry oxygen, so the more red blood cells you have, the more oxygen your muscles will receive while you run. Because less oxygen is inhaled per breath, your body has to become more efficient at delivering the limited oxygen molecules to your muscles.4Chawla, S., & Saxena, S. (2014). Physiology of high-altitude acclimatization. Resonance, 19(6), 538–548. https://doi.org/10.1007/s12045-014-0057-3
- Increasing your lactate threshold because the muscles become better at buffering the acidic metabolic byproducts of glycolysis (anaerobic metabolism). A higher lactate threshold allows you to run faster at a “steady state” or “comfortably hard” effort before feeling fatigued.5Bahenský, P., Bunc, V., Tlustý, P., & Grosicki, G. J. (2020). Effect of an Eleven-Day Altitude Training Program on Aerobic and Anaerobic Performance in Adolescent Runners. Medicina, 56(4), 184. https://doi.org/10.3390/medicina56040184
- Increasing metabolic rate and energy expenditure by 2-3 times relative to the calories burned running at sea level.6Michalczyk, M., Czuba, M., Zydek, G., Zając, A., & Langfort, J. (2016). Dietary Recommendations for Cyclists during Altitude Training. Nutrients, 8(6), 377. https://doi.org/10.3390/nu8060377
Are There Any Downsides To Training At Altitude?
Of course, there are drawbacks or risks associated with running at altitude, including the following:
- Harder to maintain the same intensity or running pace
- Dehydration7Michalczyk, M., Czuba, M., Zydek, G., Zając, A., & Langfort, J. (2016). Dietary Recommendations for Cyclists during Altitude Training. Nutrients, 8(6), 377. https://doi.org/10.3390/nu8060377
- Altitude sickness
- Slower recovery
- The costs associated with traveling to altitude or getting an altitude training tent
A sudden increase in the elevation you’re spending time in can result in altitude sickness.8Hartman-Ksycińska, A., Kluz-Zawadzka, J., & Lewandowski, B. (2016). High altitude illness. Przeglad Epidemiologiczny, 70(3), 490–499. https://pubmed.ncbi.nlm.nih.gov/27888818/
Altitude sickness is the most common risk of jumping up to a higher elevation when you live at sea level or a low altitude.
In fact, altitude sickness can occur even if you are not running at altitude or performing any vigorous physical activity, for that matter.
For example, people who live at sea level and then travel to areas like Boulder or Flagstaff, or popular tourist destinations at higher elevations such as Machu Picchu in Peru often experience symptoms of altitude sickness—or even acute mountain sickness shortly after getting off the plane.
Symptoms can be mild to debilitating and include headache, nausea, appetite loss, fatigue, rapid heart rate, dizziness, difficulty breathing, vomiting, pulmonary edema, and cerebral edema, and may last 2-4 days.
How to Train Effectively at High Altitude
If you have the opportunity to spend a significant amount of time at altitude, you can take advantage of the benefits.
However, for most everyday runners, this is not financially or logistically feasible.
Studies show9Park, H.-Y., Park, W., & Lim, K. (2019). Living High-Training Low for 21 Days Enhances Exercise Economy, Hemodynamic Function, and Exercise Performance of Competitive Runners. Journal of Sports Science & Medicine, 18(3), 427–437. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6683611/ the LHTL approach to high altitude training can provide many of the same benefits of living and training at elevation.10Wilhite, D. P., Mickleborough, T. D., Laymon, A. S., & Chapman, R. F. (2012). Increases in VO2max with “live high–train low” altitude training: role of ventilatory acclimatization. European Journal of Applied Physiology, 113(2), 419–426. https://doi.org/10.1007/s00421-012-2443-4
This would involve getting a high-altitude training tent to simulate the lower oxygen availability at high elevations. You sleep in the altitude training tent and then continue with your regular running and daily life as usual.
If you do have the opportunity to try high-altitude training, there are a few precautions that can make the process easier.
Here are my top tips for maximizing the benefits and minimizing the risks and downsides:
- Be patient. It takes time to go through the acclimatization process—usually at least 5 days for your body to start adapting and producing more erythropoietin.
- Realize that the benefits level off. Most experts say that the hematological adaptations start leveling off after about 25 to 30 days at altitude, so if you want to maximize your spike in oxygen-carrying capacity while not disrupting your life too long, a high altitude training stint of 1 to 4 weeks is ideal for most runners.
- Take iron supplements before you head off to a high-altitude training camp to help bolster your ferritin levels and maximize your hemoglobin concentration. But note that you should get a blood test first because excess iron can be toxic, particularly for males. Olympic runners undergoing high-altitude training are advised to take 60-65 mg of elemental iron twice a day with vitamin C to increase absorption.
- Focus on sleep and recovery.
- Run at a slower pace or ease your effort in workouts until you feel like you have adapted better to less oxygen.
- Consume more calories and more carbs specifically so that your body has enough fuel for a higher heart rate and greater reliance on carbs for energy, even at lower intensities.
- Hydration is key. Drink more water, as elevation exacerbates dehydration, and staying well-hydrated can help mitigate the side effects of high altitude.11Hartman-Ksycińska, A., Kluz-Zawadzka, J., & Lewandowski, B. (2016). High altitude illness. Przeglad Epidemiologiczny, 70(3), 490–499. https://pubmed.ncbi.nlm.nih.gov/27888818/ Research demonstrates that respiratory water loss at high altitudes may be increased to 1900 mL per day in men and 850 mL per day in women, and urinary water loss may increase up to 500 mL per day as well.12Michalczyk, M., Czuba, M., Zydek, G., Zając, A., & Langfort, J. (2016). Dietary Recommendations for Cyclists during Altitude Training. Nutrients, 8(6), 377. https://doi.org/10.3390/nu8060377
So, whether you want to travel to an area of high elevation, or try and simulate the effects of altitude with the “live high train low approach“, hopefully, you’ve picked up a few good tips and have a better understanding of why endurance athlete‘s and running coaches often try to employ practices that will garner the beneficial effects of altitude training.
For more information on the acclimatization process, check out the following article:
Hi Mia. Thanks for the article. Would you expect the inverse of that equation if training at altitude and going to sea level? Gut says less effective. Been running in Boulder and heading to sea level to race next month and trying to figure out a pace.
Thanks!
Grant