By now you have no doubt seen bros running around, lifting weights, or even riding around at sea level or moderate elevations with altitude training masks. The idea is to simulate the hypoxic condition of exercising at altitude (about 5,000 feet above sea level and higher). With some products, there’s also a component of ‘resisted breathing’, where you have to physically work harder to inhale and exhale. Cyclists, triathletes, and runners want to know if a altitude mask will make them faster, so let’s take a look at the science.
How an Altitude Training Mask Functions
Many of the masks available on the market simply restrict your breathing so you can’t pull air into your lungs as fast as normal. When you exercise with one you basically get out of breath sooner, at a lower exercise intensity level, than normal. You’ll also accumulate more CO2 in your blood. But the composition of the air you’re breathing is the exact same as it was without the mask. You’re only getting less oxygen because you’re getting less air.
Exposure to true altitude is different. Here in Colorado Springs at 6200 feet above sea level, the percentage of oxygen in the air is the same as it is at sea level (about 21%). But since the air pressure is lower at altitude those oxygen molecules are further apart, so there are fewer of them in a lungful of air. You’re breathing in the same volume of air, there are just fewer molecules of oxygen in it. Altitude tents and altitude rooms like the High Altitude Training Center at the US Olympic Training Center in Colorado Springs work in a similar way. They remove oxygen from the air you’re breathing so that when you draw in a full breath there’s simply less oxygen in that volume of air.
The point is, an altitude training mask is not simulating the same type of hypoxia athletes experience either living or training at higher elevations, and that seems to be a crucial difference.
The Fatal Flaws of Altitude Masks for Endurance Athletes
The short answer to the question of whether you should invest in an altitude training mask is: No. But, as with so many things in sports science, there’s more to the story because there can be benefits to exercising in a hypoxic environment, they’re just not the ones you normally associate with altitude training. First, here’s why you don’t need the mask:
Restricting Your Breathing Ruins Your Workout
As an endurance athlete, your goal is to maximize your ability to deliver oxygen to working muscles. The more oxygen you can inhale and deliver per minute, the more muscular work you can perform. When you restrict your breathing with a mask, you lose power and go slower. You’re stressing your ability to breathe, not your ability to do work. To improve fitness for endurance sports you need to accumulate enough workload to create a training stimulus, and you can’t work as hard when your breathing is restricted. Ironically, the mask makes your workout difficult and exhausting, but ultimately less effective.
Strengthening Breathing Muscles Doesn’t Improve Athletic Performance
Breathing against resistance in training doesn’t result in an increase in the amount of oxygen you can take in per minute when you remove the resistance. In other words, the strength of your intercostal muscles and diaphragm aren’t limiting factors in your ability to fill your lungs. When people report feeling like they can breathe deeper, it is likely because breathing deeply or forcefully has helped the muscles loosen up and increased the mobility of your ribs. You’ll notice the same thing if you have to take a few weeks off from exercise; after a workout or two you feel like you can take bigger breaths because your chest has loosened up.
Even Elite Athletes at Altitude Don’t Want To Train at Altitude
Athletes who live at altitude acclimate to the elevation by developing more red blood cells. That means they can train effectively at that altitude, but their power still declines when they go up into the mountains outside of town. The bigger benefit to living at altitude is the ability to go down to lower elevations for training camps where elite athletes can take advantage of increased oxygen carrying capacity in an environment where there’s more oxygen. They don’t do the opposite. They don’t live at 6,000 feet and go up to the top of mountain at 12,000 feet to do their intervals. In specialized cases we also employ supplemental oxygen training for athletes living and training at altitude. The High Altitude Training Center (HATC) at the Olympic Training Center is more often used to simulate sea level conditions than high altitude conditions. By adding oxygen athletes can achieve sea level power outputs in training, or recover in sea level conditions, while living at altitude.
Even If the Idea Was Good, the Exposure Is Too Short
Part of the reason the traditional “Live High, Train Low” method of altitude training says “live high” is because the phrase indicates how much time you need to be exposed to altitude for it to yield a positive training adaptation. Restricting oxygen for the short duration of a workout isn’t enough of a stimulus to lead to the training adaptations you’re after from altitude.
When High Altitude/Hypoxic Training Makes Sense
While the stand-alone altitude masks that operate by restricting breathing don’t improve endurance performance, there are some ways that hypoxic training can be useful.
Pacing and Perception Training
CTS Athlete Rebecca Rusch (3x World Champion, 4x Leadville 100 Champion, 3x Dirty Kanza 200 Champion) is preparing for an expedition to hike up and mountain bike down Kilimanjaro (see video below). She recently spent 3 days walking on a treadmill wearing a 40lb weight vest in the HATC, not to improve her fitness, but to determine the best pacing strategy for carrying 40lbs of gear up to 19,000 feet above sea level. When she went too fast, like accelerating from 2.2 to 2.5mph on a 10% grade at 13,000 feet, her oxygen saturation would plummet and her heart rate would spike. This was coupled with perceptions of tingly fingers and pressure behind her eyes. Together, the speed, heart rate and perception data gives her more knowledge about how to gauge her efforts. Similarly, athletes preparing for Leadville or other high-altitude events benefit from training at altitude to gain an understanding of how hard they can go and how their power and sustainable pace will be affected. Even exposure to altitude, including during short visits, can help acclimatization somewhat. With short visits you don’t have time to increase red blood cell mass, but you may stimulate ventilatory changes, which can help. This is part of the reason mountaineers go up to higher base camps and come back down when they are on their way to extremely high summits.[iframe id=”https://www.youtube.com/embed/RpMMg2OyCiU” align=”center” mode=”normal” autoplay=”no” aspect_ratio=”16:9″ maxwidth=”700″]
Intermittent Hypoxic Training
There’s another version of altitude training that could be promising for some athletes, called intermittent hypoxic training (IHT). With this method athletes perform efforts of 3-5 minutes while breathing a low-oxygen air mixture (not restricted breathing) equivalent to high altitude (11,000 feet, for example). Recovery periods between sprints are in normoxic conditions. The idea is to stimulate acclimatization to high altitude, like ventilatory response, rather than improving fitness. But again, even if a sea-level athlete wanted to try this they would need equipment like the Hypoxico Altitude Trainer Box that lowers oxygen content of inspired air, not a breathing mask that restricts total airflow.
CEO/Head Coach of CTS
with Jim Rutberg, CTS Pro Coach