Juan Murias

Our group is interested in determining the most effective exercise training programs for promoting health as well as for improving performance. The main goal of our research is related the use of exercise training interventions as “medicine” to prevent or alleviate the detrimental effects of aging and disease on cardiovascular function. Although our laboratory examines both central and peripheral cardiovascular adaptations to exercise training, a current direction of our work is focussing on the vascular side of these adaptive responses. More specifically, we are interested in the role of the endothelium in the control and distribution of blood flow and the effects of endurance training exercise in preventing or alleviating the age-related reduction in endothelium-dependent vasodilation, and the associated limitation in O₂ transport to the sites of metabolic need. Studies have reported that individuals who regularly perform endurance exercise or those who completed a 3-month endurance training program or those chronically trained (recreational and elite athletes) demonstrate a greater endothelium-mediated vasodilatory response compared to their sedentary counterparts. However, it is presently unclear what the ideal exercise dose-response is to produce favorable changes in endothelial responsiveness in different populations (ranging from young healthy to older individuals as well as clinical populations).

Some of the measures commonly assessed in our laboratory include:

• Breath-by-breath VO₂: to study of the dynamic responses of oxygen utilization during exercise transitions within the moderate-intensity domain, as well as during maximal intensity exercise.

•  Near-infrared spectroscopy (NIRS): to estimate blood oxy- and deoxygenation within the area of NIRS “inspection”. The use of this technique combined with measurements of VO₂ can provide an estimate of the matching of muscle O₂ delivery to O₂ utilization (as interpreted by the deoxy-hemoglobin/VO₂ ratio). As well, we are currently exploring the use NIRS-derived data to obtain a surrogate measure of flow-mediated vasodilation

• Doppler Ultrasound: to estimate blood flow, vascular conductance and flow mediated dilation responses in the exercise limb. Additionally, this technology is used to obtain morphological measures to derive the lumen-to-wall ratio in different arteries.

• Cardiac output using open circuit C₂H₂: to obtain measures of cardiac output during different type of exercise. This measure combined with measures of heart rate and VO₂ permits deriving estimations of stroke volume as well as systemic arterial-venous O₂ difference.

• Minimally invasive blood sampling: to measure blood gases as well as to specify exercise intensity and also to derive markers of oxidative stress and inflammation status so that some mechanistic aspects controlling adaptations to exercise training can be studied.

http://www.ncbi.nlm.nih.gov/pubmed/?term=Murias+JM

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