Local and systemic factors that impact upon vascular function in humans

Ceri Louise Atkinson

    Research output: ThesisDoctoral Thesis

    238 Downloads (Pure)

    Abstract

    [Truncated] Regular exercise reduces cardiovascular risk. Understanding the mechanisms that
    contribute to changes in vascular function following an exercise bout is essential to
    understand the basis for vascular adaptation that occurs when exercise is episodically
    repeated. Such studies provide a basis for optimisation of exercise strategies aimed at
    inducing health benefits in humans.
    Improvements in traditional risk factors such as hypercholesterolemia, hypertension and
    obesity account for approximately 50 % of the benefit of exercise in terms of
    cardiovascular risk reduction. The remaining proportion of benefit may, at least partly,
    be attributed to direct effects of exercise on the vasculature. Recent studies suggest that
    initial and rapid improvements in arterial function in response to exercise training are
    superseded by adaptations in vascular structure, and that these changes are largely
    dependent upon repeated exposure to increases in arterial shear stress and blood flow.
    Nevertheless, exercise is a complex stimulus which activates myriad vasoactive
    pathways. For example, exercise is associated with central (systemic) activation of the
    sympathetic nervous system (SNS), alongside the generation of skeletal muscle
    metabolites that induce localised changes in arterial tone. Haemodynamic responses to
    exercise also vary depending upon the modality, duration and intensity of the exercise.
    Large muscle group systemic exercise alters the haemodynamic milieu, by promoting
    large increases in shear rate and blood flow, blood pressure and neural output. In
    contrast, smaller muscle group exercise modifies arterial shear rate and local metabolic
    changes, whilst minimising changes in central haemodynamics.
    In contrast with the large number of studies illustrating that exercise improves the health
    and function of conduit arteries, few studies have specifically investigated the impact of
    training on the microvasculature. It is believed that, as is the case in larger arteries,
    shear stress and blood flow may be important stimuli at microvascular level. However,
    smaller vessels are not exposed to the same magnitude of shear and it is plausible that
    other mechanisms may contribute to microvascular adaptation to exercise training.
    The studies included in this thesis utilised a variety of methodological and physiological
    techniques to address the global aim of investigating local and systemic stimuli that
    affect the function, and ultimately health, of conduit and microvessels in humans.
    Original languageEnglish
    QualificationDoctor of Philosophy
    Publication statusUnpublished - 2015

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