Chronic obstructive pulmonary disease (COPD) is a disease of the lungs that makes it hard for people to breath. Those with COPD spend considerably more time sitting and lying and less time performing physical activity than healthy individuals. Those who are the most sedentary have a greater risk of heart and blood vessel disease, which may lead to an early death. This project will investigate the effect of sitting still for 3 hours on blood vessel health in individuals with COPD. It will also investigate whether breaking up the amount of time patients sit with regular short bouts of walking (5 minutes each hour) at a comfortable pace chosen by the patient can have a positive effect on maintaining the health of their blood vessels. It is hypothesized that blood vessel health will be worse after 3 hours of sitting compared to when the sitting is broken up by short bouts of walking.
None
performing structured exercise training (or pulmonary rehabilitation)
have a history of deep vein thrombosis
are on anticoagulant medication
have advanced cardiac or cerebrovascular disease (i.e. heart failure, previous stroke or myocardial infarction)
Crossover
Microdoses of activity
BehavioralShort bouts of low-intensity exercise (walking) will be used to break up prolonged sitting.
Change in superficial femoral artery endothelial function
The change in endothelial function (measured by the flow-mediated dilation response to reactive hyperaemia of the superficial femoral artery using ultrasound) from baseline to 3-hours of prolonged sitting in the control condition compared to performing 3-hours of sitting broken up by micro-doses of physical activity.
Difference in 24-hour ambulatory blood pressure between the two conditions
The change in average daytime, night-time and nocturnal-dipping systolic, diastolic and mean blood pressures in the control condition compared to the same pressures after performing 3-hours of sitting broken up by micro-doses of physical activity.
Change in superficial femoral artery blood flow patterns
The change in superficial femoral artery shear rate, ante-grade and retrograde flow (measured by femoral ultrasound) from baseline to 3 hours of sitting in the control condition compared to performing 3-hours of sitting broken up by micro-doses of physical activity.
Time course of change in endothelial function of the superficial femoral artery
The time course of change in endothelial function of the superficial femoral artery (as measured by the change in flow mediated dilation at each time point compared to baseline in response to reactive hyperaemia using ultrasound) after each hour of sitting in the control condition compared to the micro-doses of physical activity condition.
Change in central arterial stiffness
Change in central arterial stiffness as measured by carotid-femoral pulse wave velocity (using arterial tonometry) from baseline to 3 hours of sitting in the control condition compared to performing 3-hours of sitting broken up by micro-doses of physical activity.
Time course of change in superficial femoral artery blood flow patterns
The time-course of changes in superficial femoral artery shear rate, antegrade and retrograde flow (measured by ultrasound of the femoral artery) every 30-minutes from baseline to 3 hours of sitting in the control condition compared to compared to every 30-minutes from baseline to 3 hours of sitting broken up by micro-doses of physical activity.
Change in endothelial microparticles
The change in endothelial microparticles (CD62E+, CD31+, CD42b-) from baseline to post-3 hours of sitting in the control condition compared to performing 3-hours of sitting broken up by micro-doses of physical activity.
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