 - You will do an exercise test on the stationary bicycle. You will ride on the stationary bicycle for about 10-15 minutes while your heart rate, blood pressure, and breathing are recorded by certified exercise specialists. While you are pedaling, the difficulty level will be changed by the study staff. First, you will pedal at a low difficulty level. After a 5-minute warm up period, the difficulty level will be slowly increased for about 3-5 minutes until you reach the point you cannot continue at that difficulty level. After that point, the difficulty level will be lowered for about 5 minutes to allow you to cool down. You can stop the test at any time. 