Some athletes, among others looking for a good work out, are turning to high-altitude training masks.
The masks are worn during workouts to make a person feel as if they were exercising on a mountain top. Oxygen intake while wearing the mask is limited to strengthen lung capacity and build the diaphragm, reported CBS News.
"You're going to take less breaths per minute but you're going to take breaths that count for more," Michael Gennusa, the chief operating officer of Training Mask, which makes and sells the product, said to CBS News.
The mask comes with three different disks to control the level of oxygen that comes through the mask. The greater the altitude, the greater the workout - according to the manufacturers.
User Justin Wesley swears by the mask and attributes his faster run time and the 80 pounds he lost over the last 18 months to it.
Despite Wesley's results some experts are still skeptical of the benefits of the mask.
Dr. Benjamin Levine of Texas Health Presbyterian Hospital Dallas specializes in exercise physiology and has studied the impact of high altitude training told CBS News he doesn't believe the mask will cause significant health benefits unless, perhaps, the user sprints a lot.
"You're only spending a few minutes at altitude and that's not enough to induce any major productive changes," Levine told CBS News.
The mask is sold at sporting goods stores.
