The aims of this thesis were to explore the accuracy in measuring free-living total daily energy expenditure (TDEE), by examining existing indirect measures of energy expenditure (EE) measurement and further, developing new techniques, for improved accuracy and application, in population-based studies. In a number of the studies, the research focus is the heart rate (HR) monitoring technique, for TDEE estimation as a result of its low cost and ease of implementation in large population-based studies. This thesis represents a progression from the application of the HR monitoring technique for estimating EE in response to training, or as a means to validate a physical activity recall instrument. However, what is highlighted are the limitations of the existing methodology for estimated TDEE in this way. Therefore, this thesis introduces a novel concept in the HR monitoring technique, incorporating group-based EE equations, and further, by including the effects of the previous minutes HR response on the estimation of EE from HR. Finally, this thesis validates these modifications, using a respiration chamber, purpose-built as a part of this dissertation. It should be noted, however, that in some instances, the thesis was constrained by opportunistic sampling, or the fact that in the case of Chapter 4, the study sample was part of a larger study designed for another purpose. Nevertheless, the outcomes of this research, in particular, the group-based HR-EE prediction equations, have important implications for large population-based epidemiological research concerning physical activity dose-response. Bibliography: p. 227-253.

Includes abstract. / Includes bibliographical references (p. 157-171).

Includes abstract. Includes bibliographical references.

Includes bibliographical references (p. 197-218). / Scientific research is playing an increasingly important role in the development of optimal exercise training programmes that meet specific goals within specified times. Improving the accuracy of training prescription first involves quantifying what the athlete is currently doing. Secondly, it needs to be established whether or not the athlete is adapting favourably to the training programme. This thesis investigated current methods of quantifying training load, and proposed the use of heart rate recovery to monitor the physiological response to training. The quantification of exercise training may involve athletes self-reporting their exercise.

Includes abstract.~Includes bibliographical references. / Rugby Union is a popular international team sport characterised by frequent high impact bodily collisions known as the tackle. This aspect of the game exposes players to muscle damage and a high risk of injury. Tackle-related injuries account for up to 61% of all injuries during a rugby match. Furthermore, players’ ability to win the tackle contest has an influence on the outcome of the match. Given the nature and frequency of the tackle situation, tackle contact skills are a prerequisite for participation in rugby union. However, coaching and training drills prescribed to train the tackle to date are largely based on anecdotal evidence. To develop effective tackle training strategies (i.e. technical skills training, physical conditioning, training drills, and equipment) that will produce a successful outcome and reduce the risk of injury for both the ball-carrier and tackler, studying the tackle in real match situations is warranted. Therefore, in accordance with this goal the purpose of this thesis was to; (i) assess the current attitudes and behaviours of players during training and match play, and (ii) study the tackle and defensive strategies in real match situations.

Includes bibliographical references. / The anterior segment of the eye includes the cornea, lens, iris, ciliary body and trabecular meshwork, with each of these elements playing a vital role in the maintenance of vision. The primary objective of this research is to contribute towards the understanding of how specific genes control tissue specification and structural morphogenesis of the developing anterior segment of the eye. Despite its extensive use as a model organIsm, very little is known about the structure and development of the ciliary body in the mouse eye. Using scanning electron microscopy (SEM) the ciliary processes in the adult mouse were shown to form an irregular pattern, crossing over and interweaving, rather than lying parallel to one another, as observed in other mammals. Histological and SEM studies from E14.5 to P7 revealed that the first morphological sign of differentiation in the ciliary body is the appearance of an annular bulge around the optic cup margin; this is then gradually moulded to form discrete ciliary processes. A striking similarity between the developing capillary network and the adult ciliary folds was observed and suggests that the patterning template for the ciliary processes could be the underlying capillary network. Cell proliferation measurements and cell height assessments indicated that one of the first events occurring during the morphogenesis of ciliary processes is a proliferative surge occurring at about PO in the outer ciliary epithelium. It is likely that this surge together with increasing cell heights leads to a bulging of this layer. After a slight delay, the inner ciliary epithelium responds by proliferating and extending inwards towards the lens. Final shaping of the ciliary processes is achieved through cell height reductions in the inner ciliary epithelium. Gene expression analyses revealed dynamic changes in Bmp4 and LEF] expression patterns over the period of ciliary folding, while TgffJ1i4 expression in the ciliary body did not change during morphogenesis. These differences suggest that these genes play different roles in directing the specification and morphogenesis of the ciliary body. The temporal correlation between mitotic and cell height changes during ciliary body morphogenesis suggests that these processes play an integral role in the shaping of ciliary processes.

Includes abstract. / Includes bibliographical references (p. 183-214). / Obesity and obesity-related diseases are a large global problem in both developed and developing nations. In South Africa, a country currently undergoing epidemiological transition, the prevalence of obesity is high, particularly in urban black women. Early detection of overweight and obese individuals is essential for the management of obesity and its related co-morbidities; however, there is no ethnic-specific field measure of body fat percent validated for use in black South African women. Further, despite high levels of adiposity, these women have an atypical presentation of cardiovascular disease (CVD) risk factors, presenting with relatively low levels of visceral adipose tissue (VAT) and a favourable lipid profile compared to white women. As a result of this atypical presentation of CVD risk factors, a high prevalence of “healthy obesity” has been reported, although the determinants of this phenotype have not been systematically investigated. In addition, the applicability of commonly used diagnostic criteria for the determination of insulin resistance, which include enlarged waist circumference and dyslipidemia as components, has not been investigated in this population. Therefore, the overall aim of this thesis was to investigate the impact of body fat and its distribution on the presentation and identification of CVD risk factors in relatively young black South African women, prior to the onset of CVD. More specifically, the objectives were; i) to determine if near infrared interactance (NIR) is a valid field measure of body fat percent in South African women; ii) to determine the agreement between International Diabetes Federation (IDF) and National Cholesterol Education Program (Adult treatment panel III) (ATP III) metabolic syndrome criteria and the degree to which these criteria can predict insulin resistance, and explore the extent to which these phenomena can be explained by body fat and its distribution; iii) to identify determinants of the “metabolically healthy obese” (MHO) and “metabolically obese normal weight” (MONW) phenotypes; and iv) to complete a preliminary investigation of the association between polymorphisms within genes that encode for proteins involved in tissue-specific glucocorticoid metabolism and obesity, body fat distribution and CVD risk factors in black South African women. As obesity is associated with increased risk of cardiovascular disease, accurate quantification of body fatness is particularly important in health risk appraisal. However, in developing countries, “gold standard” measures of body fat percent such as underwater weighing and dual energy x-ray absorptiometry (DXA) are not always practical, as access to facilities and resources are limited. Therefore, a valid field measure of body fat percent is needed for the purpose of health risk appraisal. NIR is a potentially useful field measure of body fat percent that is currently used in South Africa for this purpose. However, NIR cannot be used with confidence in South Africa until it has been validated in different ethnic populations. Therefore, the first study in this thesis examined the validity of singlesite NIR (Futrex-6100 A/ZL) as a measure of body fat percent compared to the criterion method of DXA in black and white South African women.

The reliability and validity of a performance test is important in research to detect meaningful performance differences following an intervention. In accordance with this, the aim of the first study of this thesis was to investigate the reliability and validity of a self-paced 10 km treadmill time trial. This performance measure was then used in the main section of this thesis. This comprised a large training intervention study aimed to answer specific questions following three different high intensity interval training programmes. In particular, changes in 10 km running performance were investigated with respect to various physiological parameters, both immediately following the training intervention, as well as during a subsequent three-week taper period. Methods In the first study, a group of well-trained male runners (n = 8) completed four 10 km treadmill time trials and two 10 km track time trials. Comparisons in performance time were made between the 10 km treadmill time trials to determine the typical percent error between these trials. Additionally, comparisons were made between the track and treadmill time trials. In the second study, well-trained male runners(n = 32) were randomly assigned to one of four groups; a control group, a 400 m interval group, a 1600 m interval group and a mixed (400 m and 1600 m) interval group. The intensity of the intervals was based on the participants' current 10 km time trial time. The high intensity training interventions consisted of eight interval sessions (twice per week) over a four-week period followed by a three-week singlestep30% reduction in total training volume (while maintaining training frequency and some intensity) in all groups.

Bibliography: leaves 272-358. / The hypothesis, upon which this thesis is based, is that repeated bouts of damage-inducing, prolonged, endurance training and racing, over a number of years, may exceed the biological limits of the repair and adaptation process, resulting in maladaptation of the skeletal muscle and malfunctioning of the system.

There is a well described association between participation in exercise and sport and the positive effects of physical, social and psychological health. 1,2 Rugby union is a popular team sport across many countries.3 As a team sport, rugby shares these positive benefits. However, the physical demands of the game means that it is also associated with a risk of serious injuries, such as spinal cord injuries (SCIs). 4–6 SCIs have profound long-term effects on every aspect of a person’s life, including their overall quality of life (QoL).7–10 As such, a nationwide injury prevention programme called ‘BokSmart’ was launched in South Africa in 2009, with the aim to reduce and ultimately prevent these injuries.11,12 However, implementing an injury prevention programme in a country with vast socio-economic disparities, such as South Africa, is a difficult task.13 Additionally, optimal acute care after the injury, rehabilitation services and ongoing health maintenance are essential in the management of SCIs and may play a determining role in enhancing and maintaining health and functioning, and therefore QoL.14–16 In South Africa, socio-economic disparities also have a profound effect on healthcare access and the subsequent health of the population. 14 Thus, the additional burden of an injury with permanent consequences may be substantial and is an important issue to investigate. This introductory chapter summarises the literature on the incidence and risk factors for rugby-related SCIs, and the immediate management of these injuries. It also summarises the long-term healthcare issues and overall QoL of players who sustain these injuries and identifies how these problems present both globally and in South Africa. This chapter also provides the overall structure of this PhD-thesis.