I took my first gas exchange test today using the Uphill Athlete protocol. My testers were having me use the PNOE portable tool, which I was told features a fairly comfortable face mask to take the gas measurements. During the warm up I did not use the mask. I started the warm up at a 2 mph pace and 10% incline and slowly increased it to 6 mph, where I felt relatively comfortable running.

When I started the test and put the gas exchange mask on I found the mask to be very uncomfortable and it became very challenging to breath (it almost felt like I was training at elevation). In my warm up (not wearing the mask), I could comfortably run at a 6 mph pace at 10% incline; however, during the actual test, while I was wearing the mask my HR was approaching 190 at a 6 mph/10% incline pace and I felt like I was doing a very hard crossfit-type interval workout! I got off the treadmill and was totally out of breath after only 20 minutes. I started the test at a walking pace of 4 mph, and increased it at .4 mph/3 minutes. I would normally consider this to be very easy on a treadmill, but during the actual test, while I was wearing the mask, the entire workout felt very hard.

Is there some sort of learning curve associated with using the mask? My testers said it might just be because I need to spend some more time training with a mask on (they let me borrow their mask to go on a run with and are going to come back to test me again). Wondering if anybody else has had this experience where having the gas exchange mask significantly affects their performance during the test and if there is anything that can be done to get adapted to using it so I can get a better measurement.

Thanks,
Shalin