Altitude training masks are popular training items, mostly because you can look badass like Bane. They purportedly improve your cardiovascular fitness by emulating training at higher altitudes, like Michael Phelps who is known to have training stints at high altitudes. Well, don't hold your breath; save your money for a real Bane mask instead.
Image by PatLoika
Supposedly, these pricey altitude training masks work by restricting the amount of available oxygen during exercise (or really, any time you wear it). It might make sense when you think about airflow restriction, and the way your body has to adapt to perform even with less available oxygen. The problem is the science doesn't support this hypothesis. Not exactly, anyway.
In response to being at higher altitudes, the body transports more oxygen to the muscles through some cool physiological adaptations, like increasing the number of red blood cells that transport oxygen around your body (hemoglobin), greater concentration of blood vessels (capillary density) to shuttle oxygen to where it's needed, and a few others. Basically, these all would really help performance in competitive endurance athletes.
However, according to Bodybuilding.com writer Ciaran Fairman, developing these "take weeks — even months — of living and training at high altitude." Furthermore:
By restricting oxygen, you're making your body work much harder at any given workload. However, I'd offer that the intensity and workload you could achieve without the mask would be of much higher quality and allow for more adaptation than any training you would achieve with it. Whatever your training status or goals, chances are you're looking to increase your fitness level. Train to improve your VO2 max, lactate threshold, and hydrogen-ion buffering capacity. Resistance train to improve strength, power, and speed, all of which will improve endurance performance. These actions all initiate beneficial adaptations, and none of them are enhanced by a training mask.
Interestingly, if you really want to reap the benefits of the mask, it's suggested that you actually wear the mask for 20-22 hours of your day (five days a week for at least four weeks) and remove it for the hour or so of exercise you do — the complete opposite of what you'd expect!
Bottom-line: there may be some benefits if used correctly, but for the most part there is currently no evidence to suggest physiological benefits from training with the mask.
Do Elevation Masks Work? [Bodybuilding.com]