As endurance athletes look for an edge on the competition, they often turn to new gadgets, gear, or performance enhancing drugs (whether that be legal or illegal) in an effort to increase performance by fractions of an amount without truly knowing the science behind the decisions that they’re making.
Knowing this, an entire industry has dedicated itself to marketing towards these athletes, making bold claims that sound sensible on paper, but often have no evidence behind their products. There are an increasing amount of products targeting the training adaptations of your cardiopulmonary system, ranging from oxygen deprivation training masks that “enhance your training by simulating differential levels of elevation!” to bottled oxygen that “will help you maintain your body’s normal, healthy oxygen levels during a strenuous activity.” These products are small investments compared to altitude tents, which can cost upwards of $4,600. As companies claim that their products will help you improve performance, how can you be sure that these products are backed by evidence?
In this post, I break down the science behind altitude training, the marketing ploy the altitude tents use, and why the claims of these companies are unmet.
Living high - training low (LHTL) is an endurance training methodology that became popularized in 1997, after Levine and Stray-Gunderson found that “living high” (at an elevation of ~8000 feet for ~20 hours a day) and “training low” (intense training at elevation ~4000 feet) for a month significantly improved elite athlete performance (by 1-2%) at sea levels. LHTL not only increased VO2 max, it also increased erythropoietin (EPO) levels, which is the hormone that is responsible to create additional red blood cells which would help deliver more oxygen to working muscles. Importantly, these elite athletes did not show the same improvements if they lived at altitude and trained at altitude, or if they lived at a low elevation and trained at a low elevation.
After this landmark study, the media and endurance athletes alike took off with the notion that LHTL was the end-all be-all training method to live and die by. Not only that, but the notion of “living at altitude can make you a better athlete at sea-level” is still a common conception that I hear frequently today.
Before we jump on board the altitude training camp, there are a couple of key factors to consider. First and foremost – these beneficial effects don’t occur in everyone… In fact, nearly 50% of athletes are “non-responders” to altitude training, meaning that almost half of athletes show no increase in the biometric markers or performance… already seeming like a risky endeavor for most athletes who don’t have a full professional coaching and training staff.
Additionally, in 2001, Hanh & Gore published a review on the effects of LHTL on the effect of cycling performance, and (perhaps unsurprisingly) their review reported mixed results. Across a wide array of studies, LHTL “does not stimulate red cell production sufficiently to increase red blood cell volume […] there is only weak evidence of an increase in young red blood cells” and “that adaptation to hypoxia is unlikely to enhance sea level VO2max.”
The altitude tent
In partial credit to the Levine, Stray-Gunderson study (and subsequent studies) above, the altitude training camp and industry TOOK OFF between 1995-2000. These companies and devices marketed their products as the amazing solution to give you the benefits of altitude training without the hassle of travelling. You could sleep at “8000 feet elevation” from the comfort of your bedroom, wake up, and leave your sea-level house for a ride.
Furthermore, these companies also began listing devices and altitude simulators so that you could also train like you were at altitude as well.
The altitude training systems seemed like a harmonious win-win to coaches and athletes alike.
Aside from the near approximate coin flip of a chance that you won’t benefit from a proper LHTL program, there are multiple issues and disconnect between the science of altitude training and the perceived benefits of altitude simulation devices.
First and foremost, an altitude tent, system or room used at sea level during training is the exact opposite of living high, training low, where you would actually be “living low, and training high.” In essence, you would not be exposed to the potential benefits of altitude at rest or during the day, and you’d be throttling your muscles during exercise. This is just a generally bad idea, and should not be used by endurance athletes to try to increase performance at any level.
For those of you thinking of investing the ~$4000 in a tent to sleep in, remember that the landmark study to live high and train low was 20 hours at altitude, and 4 hours traveling down to a lower elevation and training. While there are other studies that have shown molecular adaptations to simulated altitude, these exact same studies failed to find increases in VO2 Max or indicators of performance.
All in all, altitude tents and training systems don’t make much sense, and I would never advise these systems to any of my athletes. Living low and training high may actually hinder endurance performance, while sleeping in an altitude tent at night is likely to yield little, if any, beneficial results.