Understanding of how walking and cycling change over time has been restricted to looking at time series data that reveals aggregate change, and time-limited longitudinal studies of individual behaviour. This thesis presents a study of the change and continuity in individual behaviour over the life course as well as inter-generational influence of, and inter-cohort similarities and differences in behavioural pathways. The behavioural trajectories of adults from two historically-separated birth cohorts, and parent-child dyads, were studied using biographical approach. Interpretive, visual biographies were produced that illustrated behavioural development through life events and transitions. Typologies were constructed to resolve common and distinct pathways in behavioural development. Behaviour change often accompanied changes in residence, employment, family structure and mobility resources. Some distinctions in trajectories were apparent along the dimensions of gender and cohort. The life-long potential for behaviour change was demonstrated by some adaptive, restorative and negative changes that occurred in later life. There was empirical suggestion that earlier cycling experiences were generative of, and influential on, later outcomes, and that some aspects of macro-level social and structural change had brought about cohort distinctions in the opportunity structure for walking and cycling over the life course. Findings were consolidated in a conceptual life course framework that proposed micro and macro-contextual influences of behaviour and addressed the temporal, gendered and inter-generational aspects of trajectory development. Emerging adulthood and, more tentatively, the work-retirement transition were periods of higher propensity for change that preceded periods of relative stability in the life course and behaviour. The findings have applications in the pursuit of measures to support life-long walking and cycling. Some recommendations for policy are made in light of indications that life course experience had distinguished some gender and cohort groups in their ability and readiness to make restorative change in behaviour.

This thesis deals with the novel application of non-linear sliding-mode control techniques to the fields of gait analysis and locomotion control. The aim of the study was to create a platform for the development of sliding-mode controlled FES (functional electrical stimulation) systems for subjects suffering neural gait disorders. A model of the human locomotive system featuring 10 pin-jointed segments and 50 functioning muscles was created. A sliding-mode controller was applied to force the simulation to follow kinematic trajectories collected from subjects using gait analysis techniques and optimisation algorithms were developed to predict possible muscle activity patterns during the sampled gait sequences. With accurate parameters, motion tracking by the system took place with an error of less than 0.25 degrees and joint moments were generated within 1 standard deviation of the expected reference curves. Significant features of the measured EMG (electromyogram) readings typically matched similar features in the simulated muscle activations. Antagonism occurred in the simulated signals in the same periods as in the reference EMG readings, i.e. where the joint angles are most sensitive to moments acting on them. This is due to the switching nature of the sliding-mode controller. Sliding-mode techniques also provide insensitivity to model-plant mismatches reducing the need for accurate parameters, of which hundreds would be required and the majority of which would be difficult to obtain. As a forward-dynamics neuro-musculo-skeletal model with an integral sliding-mode controller and optimised muscle activity estimator, the model can function both as a powerful tool for gait analysis and non-invasive EMG estimation and as a platform for the development of FES controllers for subjects with neuro-muscular gait anomalies, thus fulfilling the stated aim of the study.

Exercise is associated with a plethora of transcriptional responses preceding metabolic and cardiovascular adaptations, often attributed to ROS. The relationship between ROS and the metabolic and genomic response to exercise has not been fully defined. This thesis explored ROS generation following moderate aerobic exercise in combination with either antioxidant (lycopene) supplementation (to limit ROS formation) or hypoxia (to induce a reductive, rather than oxidative stress) in healthy males. Measures of ROS production and oxidative stress (EPR spectroscopy, LOOH, isoprostanes, SOD, LSA) and metabolism (lactate, RER) were used to quantify states of cellular stress in plasma and serum samples. These indices were considered in conjunction with microarray analysis to measure gene expression, Paxgene technique, using whole blood, post exercise. In addition, metabolomic analysis (untargeted mass spectrometry) was used to quantify differences in plasma metabolites post exercise. The results discussed within the thesis suggest that acute exercise provides stimuli for adaptations often mediated by exercise training. Lycopene supplementation may increase antioxidant capacity yet this had no measurable effect on antioxidant function, oxidative stress or gene regulation. While hypoxia appeared to increase oxidative stress this was somewhat ameliorated by exercise. Furthermore, several transcriptional responses to exercise in hypoxia were different from those in normoxia: hypoxic exercise resulted in the selective upregulation of mitochondrial transport proteins, glycolytic enzymes combined with the down regulation of AMPK suggesting an increased capacity for glycolytic metabolism and ability to withstand metabolic but not oxidative stress. Exercise caused the upregulation of genes associated with mitochondrial biogenesis, many of which were unchanged or down regulated in hypoxia. Hypoxia also appeared to reduce genome stability via the down regulation of WRN and CHAF-l. However, these changes may not be reliant upon alterations in ROS but other factors, both within and between individuals, such as insulin sensitivity, aerobic fitness or metabolic capacity.

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The thesis examines acute and chronic effects of physical training or competition on the kinetics of selected clinical and psychological markers, together with associations between some of these markers and other variables in three exercising groups.

The main focus of this thesis was to establish the effects of a novel method of undertaking isometric exercise training on resting arterial blood pressure in middle aged (45-60 years) males and to further determine whether isometric exercise training could generate concomitant adaptations in local or systemic vasculature function and structure. This novel method allowed exercise intensities to be set at a relative proportion of peak electromyographic activity (%EMGpeat). which provides a more accurate means of determining isometric exercise intensity than the traditional use of%MVC. Methods: Prior to the start of the experimental sIDdies preliminary tests were undertaken to determine the reliability of the equipment and measures used to determine the main dependant variables, including resting blood pressure using a non-invasive blood pressure monitor and vascular diameter, blood flow and velocity, using a Doppler ultrasound. During all three srudies participants completed either a unilateral or bilateral leg incremental isometric test during which heart rate, blood pressure and EMG were recorded. During the final study, resting heart rate, blood pressure and vascular measures were taken at pre, mid and post 8 weeks of isometric exercise training. Results: The linear relationship betvleen %EMG and heart rate reported in the initial study was not consistently evident in all subjects which further established the bilateral protocol as the preferred method for determining such relationships. The data from the second study involving bilateral leg isometric exercise indicated that these relationships in middle aged participants were linear in all cases, for both habitually active and sedentary individuals, showing that this method of prescribing isometric exercise intensity could be used in this age group. From the training data it is evident that following 8 weeks of bilateral isometric exercise training heart rate, SBP and mean arterial pressure (MAP) was significantly reduced in the higher (85%T) training group with concomitant local vascular adaptations. However, no significant change in resting blood press~e or vascular adaptations was evident in the lower (70%T) intensity group. These data has not been reported previously. Discussion: These results are in agreement with the majority of the previous research which have used isometric exercise training as an intervention for lowering arterial blood pressure. Furthermore, the findings lend support to the research evidence that" systeniic vascular adaptations are not responsible for the observed reductions in resting blood pressure foHowing isometric exercise training. Furthennore, the absence of changes in the 70%T group suggest the possibility of an exercise intensity threshold below which the exercise intensity is insufficient to stimulate cardiovascular adaptations.

The ratings of perceived exertion (RPE) are a widely accepted measure used to quantify, monitor and subjectively regulate an individual's exercise tolerance and level of exertion. Despite recent encouraging findings (Eston et ai, 2005, 2006), the predictive utility of the RPE during estimation and perceptually-regulated exercise tests (production) has been studied infrequently.

Many physiological variables exhibit circadian rhythmicity. The circadian rhythm in core temperature is a well-established and it has been extensively studied during both passive and exercise heat exposure. In females, a circamensal rhythm in core temperature is also present and well established. However, there is little knowledge about whether there is an interaction effect between time of day and phase of menstrual cycle on core temperature and thermoregulatory and cardiovascular responses during and following exercise. The studies in the present thesis were designed to investigate such an interaction effect on the effector responses of the thermoregulation and cardiovascular systems during the exercise and post-exercise periods. The first experiment was designed to examine the time of day effect on thermoregulatory and cardiovascular responses during and following exercise in female subjects. Eight healthy participants completed 30-min exercise at 65%Y02peak at 07:00 and 19:00hr. Core temperature was significantly higher by 0.3, 0.4 and 0.3DC at rest (P=O.OOI), during the exercise (P=O.OOI) and post-exercise (P=0.008) periods in the evening compared to the morning. The second experiment was designed to examine the phases of menstrual cycle on thermoregulatory and cardiovascular responses during and following exercise. Ten healthy participants completed two exercise protocols (65%Y02peak) during the late follicular and luteal phases of the menstrual cycle (day 10-12 and day 20-22 after the onset of menstruation, respectively). Core temperature tended to be higher in the luteal phase compared with the late follicular phase (0.2DC) both at rest (p=O.064) and during exercise (p=0.062), whereas the heat-loss mechanisms were unaffected by menstrual cycle phase. In addition, resting stroke volume and cardiac output was greater in the late follicular phase compared to the luteal phase. The third experiment was designed to explore the interaction effect between time of day and phase of the menstrual cycle on thermoregulatory and cardiovascular responses during the exercise and the post-exercise periods. Ten healthy participants completed four exercise protocol (65% Y02peak); two exercise protocols in the morning of the late follicular and luteal phases, and two exercise protocols in the evening of the late follicular and luteal phases. Core temperature was higher in the evening of both phases of the menstrual cycle during exercise (p=O.OOI) and the post-exercise periods (p=O.003). There was an interaction effect between times of day and phase of the menstrual cycle on mean skin temperature during the exercise (p=0.048) and the post-exercise periods (p=0.006), a lower mean skin temperature in the evening compared with the morning during the late follicular phase and higher in the evening than in the morning in the luteal phase. However, there was no interaction of times of day and phase of menstrual cycle for other thermoregulatory and cardiovascular parameters measured. The results in the thesis indicate that temperature regulation is set around higher values in the evening and late luteal phase of the cycle, but that these changes are likely independent of each other. Future work, should more systematically investigate these responses, collecting data at more times of day and phases of the cycle.

The existence of a specific cardiac phenotype in humans characterised as the "Athlete's Heart" is generally acknowledged. Whether athletes also exhibit characteristic vascular adaptations has received less attention. Moreover, the role of vascular structure and function in the differentiation of pathological and physiological cardiac enlargement has yet to be conclusively addressed. Recent advances in non-invasive imaging technologies have enhanced the assessment of the lumen size and wall thickness (WT) of conduit arteries. Combined with the more recent development of flow mediated dilation (FMD) techniques for the assessment of conduit arterial function, ultrasound imaging provides index parameters of vascular health. Accordingly, this thesis examined arterial structure and function in groups that demonstrate important and remarkable differences in physical activity level, ranging from elite athletes who train predominantly one side (squash players), or upper (canoe paddlers) or lower areas (cyclists, runners) versus recreational controls and spinal cord injury patients as well as wheelchair athletes. To extend this knowledge, this thesis investigated structural cardiac-vascular coupling and also to establish the arterial structure and function in Hypertrophic Cardiomopathy (HCM) patients compared to athletes with physiological enlarged hearts.