Quote (Braxton11 @ Dec 30 2017 11:11am)
Science has proven that they're worthless as fuck.
Sure it makes it seem like the workout is harder and that's because it is. You're getting less oxygen to your muscles.
The only problem is that because of the lack of oxygen, your intensity during the workout decreases which means you're not working out as hard as you usually do without the mask.
well thats not useless if your goal is to perform at altitude. but for 99% of athletes its dumb as fuck