CNS Ox Tox: Mechanisms (Diving Study for Healthy Volunteers)

If you choose to join this study, you will visit our clinic at the Center for Hyperbaric Medicine and Environmental Physiology for a screening visit to find out if you are eligible. During this visit, you will:

• Have a physical exam
• Have an electrocardiogram
• Do a series of breathing tests
• Do a strenuous exercise test on a stationary bike to calculate your fitness level (VO2 max test)

If you are eligible, you will return to our clinic to do an underwater exercise test. This test is done in a tank of water inside a hyperbaric chamber that will mimic the conditions of being 98 feet beneath the surface of the ocean. Before you begin the test, we will place a catheter (a thin, flexible tube) into a vein in your arm to take blood samples during the test. You will exercise underwater for about 10 minutes while being closely watched to ensure your safety. After this test is done, you will get a random assignment (like a coin flip) to 1 of 2 groups. You may get an assignment to:

• Do a 4-week exercise program to train your breathing muscles; OR
• Not do any training focused on your breathing muscles

If you are assigned to the training program arm of the study, you will do the exercises 5 days per week for about 30 minutes each time. About a month after your first underwater exercise test, you will return to our clinic for a second test. During this second test, 1 of the 4 following changes will be made from the first test:

• You may be assigned to do the test after you have gone 24 hours without sleeping; OR
• You may be assigned to do the test after you have gone 24 hours without sleeping and taken a stimulant medication (caffeine or methylphenidate); OR
• You may be assigned to do the test while being exposed to both warm and cold water (around 66-68 degrees fahrenheit); OR
• You may be assigned to do the test while being exposed to elevated levels of carbon dioxide

If you are assigned to one of the sleep deprivation groups, we will provide lodging for you overnight to make sure you don't go to sleep and give you a ride to the clinic and back to your home.