Isn't that whole altitude thing just a myth, unless he actually fought at the altitude he trained at?

credit for this goes to /u/smallof2pieces

I posted this a while back about the same thing, forgive the copy/paste.

It's a mask that limits oxygen intake to simulate high-altitude training.

They are a crock of crap and here's why:

The idea behind it is that high-level athletes train in high altitude locations in order to adjust their bodies to the lower oxygen level. Consequently, when they return to a lower altitude it is comparatively oxygen rich, which floods their system with extra oxygen and increases their abilities.

The problem with the mask is that you wear it for such a limited time that it in no way simulates a high-altitude environment. Even if you wear it for 2 hours a day during your work out, every day, that is still 22 hours a day you're not wearing it, and 22 hours that your body will use to readjust to the oxygen levels around you.

It does the exact opposite of what it is intended for because you are limiting your oxygen intake when you need it most - during your exercise. If you were to train in an oxygen rich environment you could push yourself further, and make better progress. Then you should move to a low-oxygen area after your workout so your body becomes accustomed to that oxygen level during recovery - and each time you enter the oxygen rich environment it will seem like there is relatively more and more oxygen.

TL;DR Technically the best training situation is to live at the top of a mountain, and train at the bottom of the mountain. This mask simulates the complete opposite - living at the bottom and training at the top.