Training with a high-altitude mask makes breathing harder, but that doesn’t necessarily equate to improved cardiorespiratory fitness. Get the truth about this popular training fad!
Source: Do Elevation Masks Work?
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.