The resting metabolic rate measures the number of calories you burn while you are resting. This test will take about 45 minutes, during which you will rest quietly in a room.  Much like the exercise test, we will analyze the air you breathe out on a machine, only now you are resting rather than exercising.  Since this test will last about 45 minutes, we will use this bubble you see here rather than a mouthpiece, nose clip, and headgear like the exercise test.  Just like the mouthpiece device had one side that was open, you can see the hole in the top of the bubble to allow you to breathe in room air.