Participant FAQs

This page answers questions that participants frequently ask us about what happens to them during the study, along with study logistics. For answers to study-specific FAQs, please visit the individual study webpage.

What sort of measurements does the research team perform?

Not all studies perform all of these measurements. If you are uncomfortable with a certain measurement or would like a measurement to be performed by a member of the same sex, we can make adjustments to ensure you feel comfortable. Please reach out to us at if you have questions or concerns about these measurements.

A measure of pressure of the blood in your arteries and a strong indicator of cardiovascular disease risk; performed with a cuff inflated around your upper arm.

A measure of blood vessel function; for this test, the research team places a blood pressure cuff around your arm (below your elbow) and an ultrasound sensor above your elbow to take a video of an artery in your arm. The cuff is inflated for 5 minutes, then released, and a video is recorded of the artery widening. You may feel your arm fall asleep or some tingling in your fingertips during this test.

A measure of the elasticity and thickness of an artery in your neck (carotid artery); for this test, the research team will place an ultrasound sensor on your neck to take a video of your carotid artery in your neck for ~1.5 minutes. 

A measure of artery stiffness; for this test, a researcher will place a small sensor on the surface of your skin at 4 artery sites (one on your neck, one on your arm, one in your hip region, and one on your wrist). They will measure how fast a pulse travels from one site to another. The quicker the pulse travels, the stiffer your arteries are.

A measure to assess brain blood flow and brain blood vessel function; for this test, the research team will place a sensor on your temple to measure blood flow through an artery in your brain. At the same time, you will wear a mask and breathe a 5% solution of CO2 (this is equivalent to how you would feel walking up a flight of stairs) for a few minutes. You may feel your heart rate and breathing increase.

A certified nurse or medical technician will insert a needle into your vein to draw blood for both safety and research reasons. Some studies will involve and IV (intravenous catheter) placement too. This is where a thin, flexible tube is inserted into the vein to allow for infusions and endothelial cell collections (see below). If you cannot tolerate blood draws at all, we recommend not taking part in our studies; if you are hesitant, please still reach out so we can discuss what your options are if you still want to participate.

In some studies, participants undergo infusions. This is when a tube is hooked up to the IV (intravenous catheter) and fluid is passed through it and into the vein. We infuse saline as a volume control. Some studies also infuse Vitamin C. Vitamin C temporarily reduces oxidative stress (a condition that can lead to cell and tissue damage) in the body to help protect the endothelial cells within our blood vessels. We are curious about how much oxidative stress affects blood vessel function, and by infusing Vitamin C we can assess whether blood vessel function improves during a state of reduced oxidative stress.

Endothelial cells line the inside of our blood vessels. They are important for controlling the function of our blood vessels. We are curious about how our studies affect certain proteins that line the blood vessels. To do this, two thin wires are inserted, one at a time, into the IV and gently moved back and forth in the vein to collect the cells. Most people can’t feel this.

Endothelial cells line the inside of our blood vessels. These cells are responsible for producing factors that widen blood vessels by causing relaxation of smooth muscle cells (another cell in our blood vessels). We are interested in knowing whether our interventions improve the ability of endothelial cells to produce these factors without affecting the smooth muscle. Nitroglycerin, a pill that causes blood vessels to widen, is administered to participants so we can assess the effects of our studies solely on smooth muscle function. We do this by taking a video of an artery in your arm with an ultrasound sensor.

Location and Parking

Our facility is located on the main CU Boulder Campus in the Ramaley West Extension. We are directly south of the Student Rec Center. You can click here for an exact location.

We offer parking close to our facility in Lot 380. Parking is free for the duration of your visits to our facility. If you require assistance getting from your car to our facility, we have golf carts we can use to help transport you. If you have questions about bus transportation or bike parking, please reach out.

Lifestyle Changes and Study Timing

Unless instructed by your provider, you should continue taking all medications as prescribed. We may ask you to refrain from consuming over-the-counter supplements before your visits, but this is only for non-prescribed supplements. We ask that you inform us of any lifestyle changes during the course of the study, including changes in medications/supplements (doses included!), exercise routine, and diet, as these could potentially impact our measurements.

We are flexible and can accommodate most vacation schedules. Please communicate any upcoming vacations to us early on.

We are enrolling participants on an ongoing basis. If you have an extended trip coming up, we can schedule you to undergo screening after your trip.

You can refer to each of our study webpages for specifics, but our studies last anywhere from ~6 weeks to ~8 months. The shortest study requires ~11 hours of your time and the longest requires ~80 hours.

A lot of potential participants are curious about the spacing of visits. You can refer to each study webpage for this info, but generally, our studies involve 1-2 screening visits over the course of ~2 weeks. Once you qualify for the study, you will undergo 1-3 baseline testing visits over the course of ~2 weeks.


You will be paid at the end of the study in the form of a check mailed to you ~1 month after you complete it. If you would prefer, we are happy to pay you throughout the study. Please let the study coordinator know.

In addition to payment for your time, you will also receive reimbursement for travel, the results from the tests performed during the study, and meal vouchers for visits lasting 3 hours or longer (if applicable to the study you enroll in). We appreciate the time you dedicate to our research!