I’m a lung doc and have spent more hours than I can count studying cardiovascular and pulmonary physiology. This makes it nearly impossible for me to ignore all the attention that elevation training masks are getting.
Before we delve into the merits of these masks, I’d first like to review a bit of physiology to highlight why altitude even potentially matters. In the best-case scenario it will help to provide groundwork for discussing training masks. In the worst-case scenario discussing this topic will allow me to feel better about paying six figures to protract my adolescence by studying well into my thirties.
At sea level we inspire air that has 21% oxygen and as you gain in altitude the partial pressure of oxygen decreases. Once inhaled, oxygen is taken into the lungs and is loaded onto red blood cells, which carry oxygen to every cell of the body to help turn our food into cellular energy. The physiological term for this is called cellular respiration -where cells use oxygen to catalyze macronutrients (carbohydrates, amino acids, and fatty acids) into cellular energy (ATP). Breath is literally life.
A person’s efficiency in utilizing oxygen is called their VO2max – a marker of aerobic fitness. Our bodies are used to experiencing a “normal” amount of atmospheric oxygen, but we often hear that training at altitude improves cardiovascular performance. We see several top distance runners, cyclists, and obstacle course racers living at high altitude for extended amounts of time. Many of these athletes take part in the live-high and train-low philosophy by training closer to sea level 1-2 hours a day (to maximize their workouts) and then spending the bulk of the day at altitude (to reap the potential benefits of living at altitude). Others incorporate high altitude training, but this may limit actual performance.
Spending extended amounts of time at high altitude can, if the oxygen content of the atmosphere is low enough, result in the kidney’s increased production of a hormone called EPO, which stimulates the bone marrow to produce more red blood cells to compensate for the lower atmospheric oxygen. Low levels of oxygen in the blood (hypoxemia) can also lead to a process called angiogenesis where new blood vessels are created in an effort to improve oxygen delivery. You have to live at high altitude for weeks to months to undergo these physiologic changes, and they are quickly lost after returning to sea level.
So, does living at altitude at places like Mammoth, Denver, and Tahoe for months lead to advantages so that you have a better chance at crushing your race because you have an enhanced capacity to deliver oxygen to your cells? Maybe.
Let’s assume that altitude training improves performance across the board (a major assumption). For those of us who live at sea level, what resources do we have to simulate high altitude? I live in Philadelphia. What can I do to simulate training in Tahoe? Not much. One option is that I could drop several hundred to a few thousand dollars and sleep in an altitude tent. These are airtight tents that decrease the oxygen content in the air you breathe so that you can spend the hours that you sleep at a simulated high altitude. Aside from not being very consumer friendly, altitude tents make it pretty challenging to snuggle and may be challenging for those of us who may be claustrophobic. So what are we left with?
Enter the aggressively marketed elevation mask.
The internet would have you believe that all you need to do is strap on one of these masks and it will transform you into Bane from Batman (your brain) or an over compensating attention seeker (my brain) and BOOM – you are now able to shave minutes off your race times because you just simulated high altitude training. Right? Wrong.
I’m not going into tremendous detail on the physiology, but lets just say that putting on an elevation mask and hitting your rower for 40 minutes three times per week at your Gold’s gym in Houston is not the same thing as living at high altitude and putting in some solid trail runs. It’s more like running with a kazoo in your mouth at sea level a few times per week.
Wearing an elevation-training mask does not lower the oxygen content of the air you breathe. That means that it won’t simulate high altitude at all. Period. It just won’t. All it does is increase the resistance your breathing muscles work against.
Oxygen delivery is determined by your cardiac output (a function of your heart rate and how much blood each beat produces), red blood cell count, and a negligible amount of dissolved oxygen in your blood. When you run hard, your blood is shunted to your legs and breathing muscles (your diaphragm and accessory muscles) because both of these muscular groups are working full tilt and demand more oxygen. This shunting is even more extreme in obstacle course racing where you feel like your entire body is begging for more blood flow (well, hopefully not your genitals) as a result of combining full body strength obstacles with technical trail running.
This shunting of blood can result in tension between your lungs and legs. Most of you that have really pushed it in a race or on a progression run know exactly what I’m talking about. You also know that, in pretty much in every case where this tension is heightened, you feel like your lungs grind you to a screeching halt while your heart races to catch your breath. You don’t pant because of weak lungs. You pant because of a build up of metabolic waste products (carbon dioxide, lactic acid) that occurs with strenuous exercise. This includes the respiratory muscles, which can fatigue long before the leg muscles do.
Maybe if you improve the fitness of your breathing muscles then you can create a scenario where they demand less oxygen per unit of time? Perhaps this will then decrease some of that tension between the legs and breathing muscles? This thinking makes some sense, but I’m not sure that wearing a mask results in a meaningful improvement. There is no consistent evidence to suggest that improving things like lung capacity or diaphragmatic strength translates to a greater running economy.
In fact, there is very good reason to think that wearing these masks may actually impair your fitness by wasting your energy on working to inhale instead of putting that same energy towards finding your optimal performance. When you are racing hard you are never faced with a scenario where you are limited by your ability to inhale. You are limited by your ability to take easily inhaled air and deliver it to your cells. The best endurance athletes have an amazing efficiency in their breathing – and these masks likely do not do a thing to improve that. But that’s just my opinion. What does the evidence suggest?
The studies that associate training benefits to wearing these masks have very small sample sizes and mostly lack control groups. Without a control group, you can’t tell if, over time, it is the exercise itself or the addition of the mask to the exercise that provides a “benefit.” Tie a ribbon around a couch potato’s finger and make them run for two weeks and their VO2max will improve. It wasn’t the ribbon that improved the VO2max. It was the running. Most studies show no improvement in VO2max and overstate the benefits of improving things like lung capacity. Of the few studies that show small effects on VO2max, there’s too much variation in who was studied (e.g. sedentary vs. those in shape, cyclists vs. runners, etc) and for how long they used the mask. Many choose to focus on various physiologic metrics that may not translate into improved racing performance. Association is not causation.
To make things more potentially dubious, makers of these products like this often finance several of the studies that are positive (a clear conflict of interest) and may be less likely to publish studies that are negative (something commonly referred to as publication bias). When I read medical literature to stay on my game at work the first thing that I read after the title are the financial disclosures. Lots of studies are funded by industry and I don’t want to be a pawn by taking things at face value. When there is a profit to be made there are potentially perverse incentives at play.
In my opinion, these masks are just another case of misleading marketing when it comes to elevation training. We all know that Red bull doesn’t give you wings. We also know that beets do not guarantee elite status (though I’m intrigued by increased nitric oxide boosting short-term performance). There’s nothing magically intravenous about some salty potion you drink orally. So it shouldn’t be surprising that masks do not make you elevate in altitude.
Perhaps you do not care if these masks do what they suggest. Maybe you just want to look like a badass and gain some sort of inner psychological advantage from looking like a comic book villain. Wearing these masks makes for some fantastic Instagram pics. I just spent a solid 15 minutes perusing IG after searching #elevationmask. Bored at your job? Search and take a gander at the plethora of mask-wearing badasses taking selfies and getting it done (sarcasm). You’ll see all sorts of Bane look-a-likes running around tracks and up hills. Strangely, you’ll see posts of brawny Banes doing heavy resistance/anaerobic work. It makes no sense to me.
Save your cash and focus on training smart and optimizing your nutrition. Take a look at what people like Ryan Atkins, Lindsay Webster, Jon Albon, and Amelia Boone are doing to not only crush OCR, but also venture into well-established road and trail running endurance events to put in truly impressive performances. They run, a lot. They run up and down mountains, a lot. They have phenomenal aerobic capacity and a great economy in their breathing. While several of these top performing OCR athletes spend a good deal of time at high altitude, not all of them do. Amelia, up until last year, lived in Chicago for goodness sake.
So what is the bottom line?
– Elevation masks do not simulate high altitude. They may improve respiratory muscle strength, but there are no consistent meaningful improvements in aerobic capacity or actual athletic performance.
– If you want to simulate high altitude then shell out money for an altitude tent and spend a significant amount of time in it. Otherwise, do not shell out money for one of these masks.
– Instead of prioritizing looking like a badass by wearing an elevation-training mask, commit to a comprehensive training plan that includes a focus on improving your aerobic capacity. Slowly increase your mileage and incorporate long trail runs, hill repeats, and speed work.
IG: @jwag511 | Twitter: @theobstacledoc