Vascular Aging Lab Director Joaquin Gonzales

Overview

Nearly half of U.S. adults have some form of cardiovascular disease. Many modifiable lifestyle factors have a strong impact on cardiovascular health. Our laboratory focuses on the multidirectional relation between sleep, physical activity, and vascular function in order to determine optimal behaviors to lower the risk for developing cardiovascular disease and promote healthy aging.

LAB MEASUREMENTs

Arterial Stiffness
Arterial stiffness refers to the thickening and loss of elasticity in the walls of arteries, which can lead to impaired blood flow throughout the body.  We employ radial artery applanation tonometry to measure parameters of arterial stiffness including augmentation index and pulse wave velocity.  Doppler ultrasound is also used to measure arterial strain, compliance, and stiffness of large arteries including the common carotid artery and common femoral artery.  

Cardiopulmonary Function
Oxygen uptake and carbon dioxide responses to exercise provide insight into heart function, skeletal muscle metabolism, and pulmonary gas exchange.  We utilize indirect calorimetry to measure these variables during cycling exercise.   Maximal oxygen uptake (VO2max) is the gold standard measure of aerobic capacity or cardiorespiratory fitness level.  We use indirect calorimetry during cycling exercise to make this measurement in adults across the lifespan.

Cerebral Vascular Function
Proper brain activation requires adequate cerebral blood flow responses for the delivery of oxygen and nutrients to neurons.  We use near infrared-spectroscopy to monitor changes in cerebral oxygenation in the prefrontal cortex during mental tasks.   Cerebrovascular reactivity refers to the ability of cerebral blood vessels to change their diameter in response to various stimuli, ensuring adequate blood flow and oxygenation to the brain.  We utilize transcranial Doppler ultrasound to assess cerebrovascular reactivity to hypercapnic challenges.

Peripheral Vascular Function
Skeletal muscle blood flow is important for physical function and exercise performance.  We use Doppler ultrasound and strain-gauge plethysmography to measure skeletal muscle blood flow at rest and during upper- and lower-limb exercise.  Beat-by-beat blood pressure is captured using finger plethysmography.  This allows for the assessment of blood pressure variability and reactivity to different stimuli including exercise.   Electrocardiography is employed in our laboratory to measure heart rate under various conditions and heart rate variability at rest.  Time-domain measures of heart rate variability accurately assess cardiac parasympathetic (vagal) activity in humans.

Physical Activity and Sleep
Actigraphy is employed to objectively measure daily physical activity using waist-worn accelerometers.  Parameters of interest include daily steps and time spent in light, moderate, and vigorous physical activity.   Wrist actigraphy is used to objectively measure sleep parameters including sleep duration, sleep efficiency (quality), awakenings, wake after sleep onset, and sleep fragmentation index.   Sleep quality, sleepiness, and symptoms of insomnia are assessed using validated surveys.

Recent findings

Narvaez G, Gonzales JU. The impact of acute sleep fragmentation on muscle blood flow responses to handgrip exercise. J Appl Physiol (1985). 2026 Sep 1;141(3):802-812. doi: 10.1152/japplphysiol.00509.2026.

Narvaez G, Gonzales JU. Reduced sleep irregularity does not impact peripheral vascular function before or following total sleep deprivation. J Appl Physiol (1985). 2025 Oct 1;139(4):909-917. doi: 10.1152/japplphysiol.00392.2025.

Gonzales JU, Narvaez G. Short-term reduction in sleep irregularity modulates cardiac autonomic function and central hemodynamic parameters at rest. Sleep Med. 2025 Sep;133:106643. doi: 10.1016/j.sleep.2025.106643.