Review on FITGAME Workout Mask: Elevate Cardio Endurance with 24 Resistance Levels, High Altitude Training Simulation - Includes Bonus Sport Bracelet and Box (Black) by Norman Costello

If you are looking for a product that will increase the power of your diaphragm to push air in and out of your lungs, this product will help. However, if you're looking for something to increase your VO2max for altitude conditioning, then don't bother adding extra resistance to the filters. Training at altitude prepares the body to produce more hemoglobin to carry more oxygen molecules in an oxygen-depleted environment. Adding some extra resistance doesn't affect this factor, rather simply wearing a mask will do the job on its own. Be careful when working out with these resistance masks as they can put tremendous strain on the body if you're not prepared for them. Start with low-resistance, low-gradient exercises so you don't overexert yourself.