Ever been recommended an elevation mask to improve your performance at altitude?

They are deceptively marketed - the name, pictures and descriptions all make the buyer think that they will actually make us more efficient at using Oxygen. At high altitudes there is less Oxygen, meaning our bodies have to make more red blood cells to catch enough per breath. These masks, however, do nothing to the Oxygen concentration in the air, they simply make it harder to breathe (training the muscles that help you get air in/out).

If you buy one of these, be clear on what it will do and when to use it, and always consult your doctor before doing so.