Three studies were designed to investigate the effects of exercise-based lifestyle interventions including diet change and exercise training on cardiovascular and autonomic responses to various physical and mental challenges in untrained premenopausal women. In Study 1, the effects of different tasks designed to activate the sympathetic nervous system on autonomic control of cardiovascular functioning such as the Stroop colour-word task (Stroop) and lower body negative pressure (LBNP) in 20 untrained premenopausal women (22.6??0.7 years) were determined. In Study 2, a longitudinal exercise intervention strategy was used with 18 untrained premenopausal women (22.5??0.7 years) in order to investigate the effect of 15 weeks of high intensity intermittent exercise (HIIE) training on cardiac autonomic responses to mental challenge (Stroop) and LBNP. In Study 3, the effects of HIIE training combined with a Mediterranean-style eating plan and fish oil supplement (Fish oil, Exercise, Mediterranean diet; FEM) on cardiovascular function during mental challenge (Stroop) and physical tasks (handgrip and reactive hyperaemia) were examined in 32 overweight untrained premenopausal women (22.0??0.6 years). In these studies, forearm blood flow (FBF) was assessed using Hokanson Plethysmography with the venous occlusion technique. The surface electrocardiogram and continuous beat-to-beat arterial blood pressure were also monitored. Peak oxygen uptake was assessed using open-circuit spirometry (True Max 2400, ParvoMedics). In addition, body composition was measured using DEXA (dual energy X-ray absorptiometry; DPX-IQ, Lunar Radiation). Results from Study 1 indicate that FBF response to mental challenge in young females was smaller compared to previously obtained data from age-matched males. Furthermore, this FBF response to mental challenge was negatively correlated to insulin resistance estimated by the homeostasis model assessment (HOMA-IR) (r = - .52, p < .05). In addition, when cardiopulmonary baroreceptors were unloaded by a mild level of LBNP (-20 mmHg) during Stoop, FBF response to mental challenge (vasodilation) was abolished suggesting a large dependency of vasodilation response during mental challenge on cardiopulmonary baroreflex. After 15 weeks of supervised HIIE training, aerobic fitness improved (p < .05) whereas percent of body fat was significantly decreased (p < .05). In addition, recovery BP following Stroop was significantly reduced. Insulin resistance (HOMA-IR) was marginally decreased (p = .056). Women who had higher insulin resistance (HOMA-IR) lost less fat than women with lower HOMA-IR (r = .60, p = .088). In addition, change in FBF during Stroop after training was directly related to pretest insulin resistance levels (r = .68, p < .05). Therefore, HIIE training had a normalising effect on FBF response to mental challenge. PEP/LVET ratio at rest and during LBNP was also significantly increased in women with higher HOMA-IR suggesting a reduction in cardiac contractility via a decrease in sympathetic stimulation (r = .62, p = .076, r = .62, p = .75 respectively). In Study 3 results indicated that 12 weeks of the FEM trial significantly reduced percent of body fat (p < .001), fasting insulin (p < .05), interleukin-6 (p < .05) and cortisol (p < .05), and significantly improved aerobic fitness ( ; p < .001). With respect to cardiovascular and cardiac autonomic measures, rate pressure product (RPP) was significantly reduced at rest (p < .05) and during recovery after Stoop (p < .05), suggesting decreased myocardial oxygen consumption. In addition, baseline heart rate determined in the sitting position was significantly reduced (p < .05), while both baseline high frequency power (HF) determined in supine (p < .01) and cardiac baroreflex sensitivity (BRS) determined in the sitting position (p < .05) were increased after the FEM trial. In addition, BRS determined during mental challenge also marginally increased (p = .051). In summary, lifestyle intervention including HIIE training, Mediterranean-style eating plan, and a fish oil supplement significantly enhanced parasympathetic influence of the heart and improved fitness, blood profiles, and body composition.

Relatively few studies have examined the effects of nociception pe se on sympathetic nerve activity in awake healthy human subjects. Painful stimuli can produce differential responses from cutaneous and muscle postganglionic sympathetic neurones in the anaesthetised cat, and some animal and human studies suggest that nociceptive stimuli originating in different tissues may produce differential sympathetic effects- deep nociception causing vasodepressive and superficial nociception triggering an excitatory effect on cardiovascular state. It is important to understand how the sympathetic nervous system responds to nociception in healthy subjects in order to make more meaningful comparisons with the behaviour which occurs following damage to sympathetic pathways, e.g. nerve lesions (chronic regional pain syndromes) and spinal cord injury (autonomic dysreflexia (AD)). Additionally, it has been suggested that muscle spindles afferents may play a role in chronic pain, most notably the 'vicious cycle' of pain. While this has been investigated in animal studies, it has not been thoroughly investigated in healthy human subjects. Muscle spindle and sympathetic nerve activity from muscle and skin postganglionic neurones were directly recorded in healthy awake human subjects using microneurography; effector organ responses (blood pressure, heartrate, skin blood flow and sweat release) were recorded in both healthy and spinal cord injured subjects. Deep and superficial nociception was induced by intramuscular and subdermal injections of hypertonic saline given at unexpected times and in quasi-random order. Regardless of the origin of nociception (deep or superficial), general responses tended to be excitatory with increases seen in muscle and skin sympathetic nerve activity, heartrate, blood pressure and sweat release. A gender effect was noted regarding skin blood flow, with males largely showing decreases and females increases. No changes were noted in spindle firing rates and painful stimuli did not significantly increase effector organ responses in spinal cord injured subjects. Contrasting with previous studies, we did not see a differential sympathetic response or change in spindle firing rate to painful stimuli originating in different tissues. While it is believed that noxious stimuli trigger AD, we did not see exaggerated sympathetic responses in spinal cord injured subjects. More investigation is required regarding innocuous triggers of AD.

Additional appendix (5 p.) is pasted onto back end-paper. / Bibliography: leaves 219-244. / v, 244, [14] p., 67 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Investigates the complexity of the vagal reflexes arising from the upper gastrointestinal tract by recording single unit vagal afferents and efferents in the ferret. The potential involvement of various neurotransmitters in mediating and modulating gastrointestinal tract inputs is also explored. / Thesis (Ph.D.)--University of Adelaide, Dept. of Medicine, 1999

Relatively few studies have examined the effects of nociception pe se on sympathetic nerve activity in awake healthy human subjects. Painful stimuli can produce differential responses from cutaneous and muscle postganglionic sympathetic neurones in the anaesthetised cat, and some animal and human studies suggest that nociceptive stimuli originating in different tissues may produce differential sympathetic effects- deep nociception causing vasodepressive and superficial nociception triggering an excitatory effect on cardiovascular state. It is important to understand how the sympathetic nervous system responds to nociception in healthy subjects in order to make more meaningful comparisons with the behaviour which occurs following damage to sympathetic pathways, e.g. nerve lesions (chronic regional pain syndromes) and spinal cord injury (autonomic dysreflexia (AD)). Additionally, it has been suggested that muscle spindles afferents may play a role in chronic pain, most notably the 'vicious cycle' of pain. While this has been investigated in animal studies, it has not been thoroughly investigated in healthy human subjects. Muscle spindle and sympathetic nerve activity from muscle and skin postganglionic neurones were directly recorded in healthy awake human subjects using microneurography; effector organ responses (blood pressure, heartrate, skin blood flow and sweat release) were recorded in both healthy and spinal cord injured subjects. Deep and superficial nociception was induced by intramuscular and subdermal injections of hypertonic saline given at unexpected times and in quasi-random order. Regardless of the origin of nociception (deep or superficial), general responses tended to be excitatory with increases seen in muscle and skin sympathetic nerve activity, heartrate, blood pressure and sweat release. A gender effect was noted regarding skin blood flow, with males largely showing decreases and females increases. No changes were noted in spindle firing rates and painful stimuli did not significantly increase effector organ responses in spinal cord injured subjects. Contrasting with previous studies, we did not see a differential sympathetic response or change in spindle firing rate to painful stimuli originating in different tissues. While it is believed that noxious stimuli trigger AD, we did not see exaggerated sympathetic responses in spinal cord injured subjects. More investigation is required regarding innocuous triggers of AD.

Diss. (sammanfattning) Stockholm : Karol. inst., 2003. / Härtill 5 uppsatser.

Thesis (Ph.D.)--University of Wollongong, 2004. / Typescript. Includes bibliographical references: p. 239-266.

Diss. (sammanfattning) Umeå : Univ., 2006. / Härtill 6 uppsatser.

Thesis (Ph. D.)--University of Sydney, 2007. / Title from title screen (viewed 1 November 2007). Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the Discipline of Physiology, Faculty of Medicine. Degree awarded 2007 ; thesis submitted 2006. Bibliography: leaves 239-284. Also issued in print.

Zugl.: Braunschweig, Techn. Univ., Diss., 2008

Thesis--Uppsala. / Without thesis statement. Bibliography: p. [152]-162.