Running With an Altitude Mask: Science or Snake Oil?

Last Updated on February 17, 2022 by Heather Hart, ACSM EP, CSCS

An altitude mask – sometimes called an elevation mask – is a training device that, according to manufacturers and their marketing team, is supposed to simulate training at altitude by restricting the amount of air you can breathe while working out, thus, making you stronger/fitter/faster/take your pick.

Many athletes consider training or running with an altitude mask under the assumption that the mask will help them either:

1. Become a better athlete by simulating the positive physiological adaptations that happen to endurance athletes who train at high altitude, or
2. Will help them prepare for success at a race that takes place at higher altitude by allowing them to “acclimate” without actually living or training at higher altitudes.

Unfortunately, there is absolutely no reputable evidence that either of these things happen with altitude training masks.   

But instead of leaving it there, (you know I love writing about running science almost as much as I love running itself) let’s discuss exactly what these training masks are doing…and why it’s most likely NOT what you thought they were doing.

Buckle up, friends. We’re finally diving into this one. 

What is an Altitude Mask, or Elevation Training Mask ?

An altitude training mask is a device worn over your mouth and nose while running or training that is designed to make breathing more difficult. They look absolutely ridiculous and/or badass, depending upon your desire to look like comic book supervillain.

The masks typically feature some sort of adjustable nozzle that allows users to adjust the amount of air that flows into the mask with each breath.

The idea, of course, is that by making it harder to breathe, the mask is limiting the amount of oxygen available for an athlete, simulating the hypoxic conditions of high-altitude training.

And athletes have bought into these claims…hard. Chances are you’ve seen someone at your gym wearing a mask, or a runner logging miles with one of these over their face.

If not, you only need to search the internet for “training mask” to find proof: there are hundreds and hundreds of pages of results featuring various brands of training masks you can purchase.

Maybe you even own a mask yourself. No judgement from me, my supplement closet is likely full of placebos I’m convinced do something beneficial for me.

But there are a number of flaws behind the idea that restricting air flow with a workout mask will illicit any sport, fitness, or running performance gains. My hope is that this post will help you better understand why.

The Science Behind Running at Altitude 

In order to understand if a mask can truly simulate altitude, it’s important to understand what altitude means, and how it affects the human body. Yeah, yeah, it’s time for a brief bit of science…but this bit is important.

Chances are you already know – either from personal experience or just commentary in your favorite Facebook running group – that running at higher altitudes (compared to where you live and normally train) can feel MUCH harder.

I experienced this myself the first time I left sea level South Carolina for the mountains of Colorado. Despite being in great physical shape at the time, simply walking 100 yards up a small hill from the cabin we stayed in to the campground office left me so winded, it felt like I had just climbed 100 flights of stairs.

I won’t even bore you with how much it affected my running performance (but we DID successfully complete the 6 day, 120 mile Transrockies Stage Race with our sea level lungs).

Why is it Harder to Run at Higher Altitudes?

As altitude increases, barometric pressure (sometimes referred to as atmospheric pressure, it’s the pressure of the air around you) decreases. And as the barometric pressure decreases, the partial pressure of oxygen decreases, resulting in a hypoxia – or a low oxygen environment. In turn, this results in hypoxemia, or, low partial pressure of oxygen in the blood, which absolutely affects humans and athletic performance.

That was a lot of possibly confusing science terminology, so here are the simplified highlights:

• The air you inhale with each breath you take is composed of about 21% oxygen, 78% nitrogen, 0.9% argon, and trace amounts of other gasses.
• No matter where you are on earth, these percentages do not change.
• What does change with altitude is barometric pressure, or, the density of gas particles in each breath you take.
• At sea level, the barometric (air) pressure is760 mmHG
  • since Oxygen is 21% of the air, the partial pressure of oxygen at sea level is 159 mmHG
• In Denver, Colorado (5,202 feet above sea level), barometric pressure is 631 mmHG, and partial pressure of oxygen is 132 mmHG (21% of 631).
• Our bodies rely on a pressure gradient to help move oxygen from the lungs into the bloodstream, and to move carbon dioxide out of the blood stream and into the lungs. The lower the pressure of the air, the harder this process becomes.

What does that all mean? The higher the barometric pressure, the closer together gas molecules are. The lower the barometric pressure, the more spread out gas molecules are.

Therefore, with each breath you take at higher altitudes, you are getting less oxygen molecules per breath compared to lower altitudes, and your body has to work harder to get that oxygen into your bloodstream, resulting in lower blood oxygen saturation.

Your body needs oxygen to function. Thus, with less oxygen available, any physical activity at higher altitude (compared to where you normally train and live) can initially feel significantly harder.

How Does Your Body Adapt to Altitude? 

So, what happens to your body when you live, train, and run at altitude over time?

After spending time at higher altitude, your body wants to compensate for the lower partial pressure of oxygen, and therefore adapts in a number of ways to help increase blood flow throughout your body. These adaptations, which can take multiple weeks to multiple months, include:

• Both pulmonary ventilation rate (the amount of air you breathe in) and heart rate increases, both at rest and with exercise. 
• The lack of oxygen at altitude signals your kidneys to release erythropoietin (EPO) – a hormone responsible for stimulating the production of red blood cells (technically called erythrocytes). This happens almost immediately, within three hours of arriving at higher altitude. 
• EPO levels continue to rise for about 2-3 days, and remain elevated upwards of a month. Red blood cell count can remain elevated for upwards of 3 to 6 months before leveling out, resulting in about a 10% increase in blood volume compared to living at sea level. 
• As the blood’s erythrocyte volume increases, so does the blood’s hemoglobin concentration, and thus the oxygen-carrying capacity of your blood increases.
• Plasma volume increase as a response to altitude acclimatization means your maximal cardiac output (the amount of blood your heart pumps per minute)  increases, again, increasing your oxygen delivery capacity
• Studies show that capillary density in muscles increases as a response to time spent living and training at altitude.  Greater capillary density allows more blood, and therefore oxygen, to be delivered to the muscles

All of these adaptations sound incredibly beneficial to athletes, who rely on the body’s oxygen carrying capacity to supply oxygen to the muscles in order to provide energy, and keep us moving.

So it makes perfect sense why we’d want to simulate these adaptations, even when we live at sea level.

Do Altitude Masks Actually Work for Simulating Altitude Training? 

When considering if altitude masks actually mimic training at altitude, the answer is no, they do not. That’s because, as we’ve learned, the partial pressure of oxygen at higher altitudes is lower than at sea level. When utilizing an altitude mask, you are not changing the barometric pressure nor partial pressure of oxygen. (Unless you’re using the altitude mask AT high altitude, which is probably not a good idea).

With a mask, you’re simply restricting air flow, or making your body work harder to take in the same total volume of air with each breath as you would if you were not wearing the mask.

But regardless of the amount of air intake, the oxygen content is still the same.

According to a 2020 study, even restricting air flow by using a training mask will not induce hypoxia to a high enough level to elicit all of those seemingly awesome adaptations to high altitude mentioned above. (1)

Are There Any Performance Benefits to Running with an Altitude Mask? 

Maybe? But unfortunately, current available research is pretty limited…and mainly limited to studies on men at that (unfortunately a common occurrence in the world of science, but I digress).

I can almost hear the mask wearers saying “But…running with an altitude mask is HARD! There has to be some sort of benefit, right?”

Nevertheless, let’s look at some more hypotheses regarding physical performance benefits of altitude training masks, and what research has found so far:

Do Altitude Masks Increase Lung Capacity or Improve Lung Function?

For athletes, the answer is most likely…no, there are no pulmonary benefits to running with an altitude mask. This is because, in most cases, the respiratory system and lung function in healthy athletes is already overbuilt for its demands (4)

Research shows that any known inadequacies in the respiratory system do not occur in all healthy subjects, and when they do, they account for relatively minor limitations to sport or running performance (4) Most research showing any improvements in respiratory function through interventions was studied on those with unhealthy lung function, such as those with COPD.

According to Nick Tiller (MRes, Ph.D.), a senior researcher in respiratory medicine & exercise physiology at Harbor-UCLA:

“There are no commercial interventions (exercises, devices, or supplements) that can increase your lung size. Lung size is determined by genetics, just like height, eye color, and shoe size. Accordingly, once you’ve physically matured (usually by your early twenties) your stature and lung size are set. Be wary of any product claiming the contrary.” (8)

Do Altitude Masks Increase Respiratory Muscle Strength?

The respiratory muscles consist of the diaphragm, the rib cage muscles and the abdominal muscles, and they are responsible for the actual mechanical work of inhaling and exhaling. Limited research shows that performing HIIT while wearing a mask may improve respiratory muscle function that has potential to postpone respiratory muscle fatigue (3)

How might this help a runner? Through a response to intense exercise known as metaboreflex.

Respiratory Muscle Metaboreflex

Despite an athlete’s mental toughness or willingness to push themselves, the human body will always prioritize the bodily functions necessary for survival. 

Respiratory muscle metaboreflex is a response to intense exercise, where the body will restrict blood flow to the limbs when respiratory muscles fatigue (5).  Instead, it diverts that blood to the lungs, because lung function is more important.

In theory, stronger respiratory muscles will both take longer to fatigue, and recover faster, limiting the effects of metaboreflex on your leg muscles. Therefore, stronger respiratory muscles could result in better running performance.

Will Training in an Altitude Mask Increase VO2 Max?

The limited research available so far demonstrates that altitude masks will not increase your VO2 max. But not all hope is lost…the studies did observe a concrete way to make improvements in your aerobic capacity.

A 2017 study set out to investigate whether or not these hypoxia inducing training masks would have an effect on VO2 max and pulmonary function. They utilized a high-intensity interval training (HIIT) protocol while running on 17 healthy and already moderately trained men and women over the course of 6 weeks. 9 participants training in the altitude masks, and 8 participants were in the control group, meaning they did not wear a mask while training.

The results?

Both the experimental and control groups demonstrated an increase in forced vital capacity (FVC- the amount of air that can be forcefully blown out after full inspiration) and forced inspiratory vital capacity (FIVC – a forceful lung inspiration that was preceded by maximal lung expiration) at the completion of the HIIT protocol, but there was no statistical, significant differences between the groups. (2)

Further, VO2 max did indeed increase at the end of the 6 week HIIT protocol, both in the mask group and in the control group.

However, there was no significant difference between the two groups, leading researchers to conclude that it was the interval running protocol – and not the masks themselves – that led to gains in VO2 max.

Will Altitude Masks Increase Mental Toughness?

Training with an altitude mask is, no doubt, significantly more difficult. So can it help a runner build “mental toughness” to push through difficult times during a training run or race?

Sure, these masks can absolutely help with that. But at what cost?

Numerous studies have shown that athletes running or training in altitude masks perform at lower intensities and/or volumes compared to when they do not wear the masks (7). Since physical adaptations occur over time at desired exposure, why would you want to hinder your ability to train at your desired intensity?

Just because it’s “harder” doesn’t necessarily mean it’s “better”.

More Altitude / Elevation Training Mask Misconceptions

But wait, there’s more!

Over the years, many of these altitude mask marketing teams have transitioned away from highlighting the “altitude” portion of the mask, and instead focus on a number of other supposed benefits of the training masks.

Most Altitude Adaptations Don’t Happen During Training

An important thing to remember is that these aforementioned adaptations to altitude? They happen over time, and more specifically, during rest.  

There is a reason why many elite athletes choose to sleep in an altitude tent – which do lower the barometric pressure inside the tent to simulate altitude and create a hypoxic environment – rather than train in them. The exposure time needed for true adaptation takes considerable time.

Further, many professional athletes follow the “live high, train low” training methodology, in which they train at lower altitudes, allowing them to truly push themselves without the limitations of altitude, and then recover (or “live) at higher altitudes, to reap the benefits of adapting to altitude.

Point being? Even if altitude masks did truly simulate altitude, you’d be better off training without the mask, then spending the rest of your day and night recovering while wearing the mask.

Harder Breathing Isn’t Always An Indicator of Poor Lung Function

A common misconception in athletes is that when the intensity of exercise increases, labored breathing (rapid or deeper breaths) happens because they “aren’t getting enough air” into their lungs. So if a mask makes you breathe harder, you must be getting “better” at “getting more air”, right?

Not necessarily.

Researchers say that it’s common for unfit or less fit individuals with no evidence of lung issues to complain of labored or difficult breathing during exercise. Why? Well because their ability to actually utilize the oxygen they breathe in – their aerobic capacity – is lower.

The body’s natural response is to increase breathing rate, to try and get more oxygen to the working muscles. Again, it’s not that you aren’t taking enough in per breath, it’s that your body isn’t as efficient as it could be at using the oxygen you breathe in.

Eventually you hit what is known as your ventilatory threshold, this is where your breathing increases disproportionately to the amount of oxygen you can consume. This results in a greater amount of carbon dioxide production compared to oxygen consumption. And your body needs to get rid of carbon dioxide…so you’ll keep breathing harder.

The good news is that you can increase aerobic capacity with regular exercise.

What are Alternatives to Running with an Altitude Mask?

So, if altitude masks don’t really do what they say they do, what are the alternatives? How can you become a better, stronger, faster runner, or train appropriately for a race at altitude?

The simple answer is: train smarter.

Experts agree that high altitude training among elite competitive athletes is done as a means to make minute performance improvements in a population that is already incredibly fit. These small, 1-2% increases in performance can make the difference between 1st place and 2nd place among professionals.

Amateur athletes, however, would likely benefit far greater from focusing their attention on increasing their overall fitness through focused, proven training methodologies.

In short, the scientific consensus with the current limited research is: running with an altitude mask isn’t going to help either improve your running performance, or improve your ability to race at altitude.

Resources:

1. Barbieri, J. F., Gáspari, A. F., Teodoro, C. L., Motta, L., Castaño, L., Bertuzzi, R., Bernades, C. F., Chacon-Mikahil, M., & de Moraes, A. C. (2020). The effect of an airflow restriction mask (ARM) on metabolic, ventilatory, and electromyographic responses to continuous cycling exercise. PloS one, 15(8), e0237010. https://doi.org/10.1371/journal.pone.0237010
2. Biggs, N. C., England, B. S., Turcotte, N. J., Cook, M. R., & Williams, A. L. (2017). Effects of Simulated Altitude on Maximal Oxygen Uptake and Inspiratory Fitness. International journal of exercise science, 10(1), 127–136.
3. Cheshier, BC; Estrada, CA; Moghaddam, M; Stewart, CJ; and Jacobson, FACSM, BH (2019) “EFFECT OF ELEVATION TRAINING MASK IN CONJUNCTION WITH HIGH INTENSITY INTERVAL TRAINING ON LUNG FUNCTION,” International Journal of Exercise Science: Conference Proceedings: Vol. 11 : Iss. 7 , Article 58.
4. Dempsey, J. A., La Gerche, A., & Hull, J. H. (2020). Is the healthy respiratory system built just right, overbuilt, or underbuilt to meet the demands imposed by exercise?. Journal of applied physiology (Bethesda, Md. : 1985), 129(6), 1235–1256. https://doi.org/10.1152/japplphysiol.00444.2020
5. Harms C. A. (2007). Insights into the role of the respiratory muscle metaboreflex. The Journal of physiology, 584(Pt 3), 711. https://doi.org/10.1113/jphysiol.2007.145540
6. Jagim, A. R., Dominy, T. A., Camic, C. L., Wright, G., Doberstein, S., Jones, M. T., & Oliver, J. M. (2018). Acute Effects of the Elevation Training Mask on Strength Performance in Recreational Weight lifters. Journal of strength and conditioning research, 32(2), 482–489. https://doi.org/10.1519/JSC.0000000000002308
7. López-Pérez, M. E., Romero-Arenas, S., Colomer-Poveda, D., Keller, M., & Márquez, G. (2020). Psychophysiological Responses During a Cycling Test to Exhaustion While Wearing the Elevation Training Mask. Journal of strength and conditioning research, 10.1519/JSC.0000000000003626. Advance online publication. https://doi.org/10.1519/JSC.0000000000003626
8. Tiller, N. (2021, December 20). Can you breathe your way to better health? The science and pseudoscience of ‘training your lungs’. Skeptical Inquirer. Retrieved February 15, 2022, from https://skepticalinquirer.org/exclusive/can-you-breathe-your-way-to-better-health-the-science-and-pseudoscience-of-training-your-lungs/