This thesis is presented as a collection of four studies in which the role of self-control in athletic performance is examined. Considerable evidence has documented the beneficial effects of trait self-control and robust self-confidence on a wide range of behaviours. However, the relationships between these constructs have yet to be specifically explored within the sport domain. As well as exploring the trait perspective of self-control, research has employed self-control manipulations and laboratory performance to examine state self-control. The completion of tasks requiring self-control have led to impaired performance on physical tasks, also requiring self-control. But it remains unclear whether previous exertion of self-control impairs subsequent performance when self-regulation is potentially automatic, and if any observed effects are variable over different stages of performance. Building on this work, glucose supplementation, and the duration of self-control effort have been proposed as potential moderators that may influence performance effects, yet controversy exists surrounding glucose consumption, and task duration has not been appropriately considered. Furthermore, the identification of explanatory mechanisms for performance decrements following self-control use is of theoretical significance. In particular, research is yet to explore whether an individual s perceptions of pain may explain why self-control exertion interferes with subsequent performance on a physical task. The current thesis aims to address these limitations of the extant literature. Study One examined whether an individual s general ability to exert self-control might be an important mechanistic variable that explains the relationship between robust self-confidence and athletic performance. Following an examination of trait self-control, an exploration of state self-control was deemed more relevant to situational performance. Therefore, Study Two and Three utilised a sequential-task paradigm to examine whether exerting self-control impairs subsequent endurance performance in well-trained individuals, and whether any observed effects are variable over different stages of endurance performance. Study Two and Three also examined moderators of the depletion effect. In particular, the potential for glucose supplementation (Study Two), and duration of self-control effort (Study Three), to attenuate any decrements in performance due to initial self-control exertion were explored. Following the investigation of moderators, Study Four examined whether performance decrements can be explained by an individual s perceptions of pain. Overall, the findings of this thesis suggest that trait self-control represents a potentially important mechanism by which athlete s with strong robust self-confidence progress and perform successfully. Furthermore, prior exertion of self-control impairs subsequent self-regulatory efforts during well-practiced endurance performance, but these effects are variable over different stages of performance. In addition, extended self-control effort may lead to the conservation of self-control, whilst glucose supplementation does not moderate self-control ability. Finally, perceptions of pain may explain why self-control exertion interferes with subsequent performance on a physical task.

Le trail running, course nature de distances, dénivelés et technicités variables, est une discipline récente à la popularité croissante. La performance en trail dépend de nombreux facteurs génétiques, énergétiques, techniques, stratégiques et motivationnels. Parmi ces facteurs, le coût énergétique de la locomotion fait débat. Les études de cette Thèse s'attachent aux corrélations plat/montée de cette variable, au calcul d'un coût en pente à partir d'un coût à plat, à l'influence de la modification forcée de la fréquence de foulée sur l'énergie consommée, et à l'impact de la fatigue générée par un ultra trail sur le coût à plat et en montée. La prise en compte des contraintes musculaires et biomécaniques en trail d'une part, des facteurs influençant l'économie de course d'autre part, ainsi que des résultats de notre principale étude de terrain, nous laissent émettre l'hypothèse que le coût énergétique et ses variations pre/post course à plat/montée, ne sont pas des indicateurs de performance de l'activité. La force, l'endurance de force et le pacing, en plus de la puissance aérobie et de l'endurance, sont les variables testées les mieux corrélées à la performance en ultra trail / Trail running is a discipline with increasing popularity over the last 2 decades. Trail performance depends on many genetic, energetic, technical, strategic and motivational factors. Among these factors, the energy cost of locomotion is debated. The studies in this Thesis focus on the level/graded correlations of this variable, on the calculation of an uphill cost from a level cost, on the influence of a forced modification of stride frequency on running economy, and on the impact of fatigue generated by an ultra trail on level and uphill costs. Taking account of the muscular and biomechanical constraints on the one hand, and the factors influencing the running economy on the other hand, as well as the results of our main field study, we hypothesize that energy cost and its pre/post fatigue variations, are not performance indicators of the activity. Force, endurance of force and pacing, in addition to aerobic power and endurance, are the tested variables best correlated to ultra trail performance

Running economy is well established as a primary determinant of endurance running performance. However, there is a lack of clarity about the preferred measurement of running economy, its primary limiting factors and the most robust methods enhance running economy in highly trained athletes. Therefore, this thesis investigated the running economy of highly trained runners, exploring the reliability and validity of measures of running economy to deduce its most appropriate quantification, the application of innovative methods to enhance our understanding of an athlete s running economy, and a novel training method to enhance running economy. Chapter 3 revealed that energy cost and oxygen cost were shown to provide similarly high levels of reliability (typical error of measurement ~3%) for highly trained endurance runners when assessed using a short-duration incremental submaximal exercise protocol. In chapter 4, the analysis of a large cohort of highly trained endurance runners revealed that energy cost increased in a stepwise manner with increments in running speed (P<0.001), however oxygen cost remained consistent (P=0.54) across running speed; indicating that oxygen cost might not be an appropriate measure of running economy. Chapter 5 demonstrated that the inter-individual variation in the magnitude of changes in energy cost between different gradients (i.e. from flat running to uphill/downhill running) in highly trained runners was low. However, a disparity between the energy saving of running on a -5% gradient (-17%) and the additional energy cost of running on a +5% gradient (+32%) was evident. The cross-sectional and longitudinal analysis of a large cohort of highly trained runners in chapter 6 revealed a small (r=0.25) and moderate (r=0.35) association between energy cost and maximal oxygen uptake, respectively. Finally, chapter 7 demonstrated that eight weeks of supplementary downhill run training at vLTP in existing training programmes does not enhance running economy in already well trained runners (1.22 vs 1.20 kcal kg-1 km-1; P=0.41), despite a significant increase (+2.4%) in the velocity at lactate turnpoint. In conclusion, this thesis demonstrates that energy cost, expressed as kcal kg-1 km-1, provides a reliable and valid method to quantify running economy in trained distance runners. However, further investigation is required to identify robust training methods to enhance running economy in this already highly trained population.

Choosing to Run: A History of Athletics and Gender in Kenya, c. 1940s – 1980s explores the history of gender and athletics in Kenya, with focus on the Rift Valley Province, from the onset of late colonial rule in the 1940s through the professionalisation of the sport during the last decades of the twentieth century. The first two empirical chapters provide a history of athletics during the colonial period. The first highlights the continuity of ideas about sport and masculinity that were developed in nineteenth century Britain and were subsequently perpetuated by the men in charge of colonial sport in Kenya. The next chapter considers how pre-colonial divisions of labour and power within Rift Valley communities informed local peoples' cultures of running. The absence of women’s running was not only the result of sexism translated from the British metropole to its Kenyan colony but also of pre-existing divisions of responsibilities of indigenous Kenyan men and women into separate, gendered domains. The second half of the thesis considers the impact of social change within women’s athletics internationally and of marriage, childbirth and education locally on female runners in the Rift Valley during the post-colonial period. Most women abandoned athletics once they reached maturity. Those who sought to do otherwise, as the final chapter argues, found that they could only do so by replicating the prototype of masculine runners that had already been established. Later, after the professionalisation of running allowed women to become wealthy, female patrons took this a step further by providing resources to those in their community in need, setting themselves up as 'Big (Wo)men'. This thesis uses athletics to reveal how gender relations and gender norms have evolved and the benefits and challenges that the sport has brought both to individual Kenyan women and their communities.