In an effort to boost performance, some athletes use altitude tents to promote hypoxia, a lack of oxygen that forces the body to distribute oxygen more efficiently. Do such tents actually work? Michael Koehle, an Associate Professor in the Division of Sports Medicine and the Environmental Physiology Lab explains.
What is hypoxia?
Hypoxia means low oxygen. We usually mean low oxygen in the environment around you when we talk about hypoxia. First, there’s hypobaric hypoxia which mean low pressure hypoxia which occurs at high altitude. When you go to altitude, the amount of atmosphere above you is less so the pressure is less. As the pressure decreases the amount of oxygen in the air you breathe would go down.
If someone was at Everest Base Camp, the atmospheric pressure there is about half what it is in Vancouver, which is at sea level. The actual amount of oxygen molecules would be half of what it is in Vancouver.
The other type of hypoxia is normobaric hypoxia. That’s what you have with hypoxic tents. You hear about athletes training in either hypoxic houses or hypoxic tents. How those work is that they don’t change the pressure at all, but they actually dilute the amount of oxygen in the air.
Do altitude tents work?
There’s always been a question whether the hypoxic tents and the normobaric hypoxia are equivalent to real outdoor terrestrial altitude or to the hypobaric chambers. That’s a question that hasn’t been adequately answered.
The goal of the study where we were comparing normobaric hypoxia and hypobaric hypoxia was to use a very rigorous design so the subjects experienced both types of hypoxia as well as a “sham” condition—they’re actually at sea level pressure and sea level oxygen and they don’t know it. And then a fourth condition where they actually had low pressure but the same amount of oxygen at sea level.
What were the results?
We looked at a bunch of these different parameters under all the conditions. We really couldn’t find any significant differences—differences either in the rate of altitude illness or differences in the amount that people breathe or the way that their body compensated for the altitude.
What does this mean for mountain climbers?
For people who have to go to altitude, some of them will prepare by training in a hypoxic tent or using devices similar to a hypoxic tent. We previously didn’t know whether that was effective training. We didn’t know whether the hypoxia they were using in training was going to affect their body similarly to the true altitude. The findings of the study show that these surrogates for true altitude seem to be similar enough to create the same kind of response in the body to altitude.