Many consider that maximum oxygen uptake (VO2 max) provides a valid measure of fitness in general and endurance capacity in particular. However, in recent years evidence has accumulated suggesting that VO2 max values provide only limited information regarding endurance capacity. This study set out to investigate the influence of training on the maximum oxygen uptake and endurance capacity of male and female subjects. The investigation consisted of three studies. The first described the relationship between VO2 max correlation between VO2 max and Z individuals within the group with differently. The second study examined the influence of short term training on VO2 max and endurance capacity. The increase in VO2 max was small (7%) when contrasted with the large improvement in endurance capacity (478%). The above two studies both indicated that VO2 max alone does not determine endurance capacity. The third study therefore set out to examine which factors influence changes in VO2 max and endurance capacity after a period of endurance training. By adopting a single-leg exercise model (Davies and Sargeant, 1975), this study not only re-examined the relationship between VO2 max and endurance capacity but also attempted to separate local and central adaptations to training. This model was adopted because of the suggestion that increases in endurance capacity are the result of changes in the skeletal muscle (local) (Gollnick et al., 1973). Again, the increases in VO2 max were small when compared with the improvements in endurance capacity. Improvements in the trained leg (TL) were attributed to central and local adaptations to training and in the untrained leg (UTL) to central cardiovascular changes. The large increase in the endurance capacity of the TL (523%) was 404% greater than that seen in the UTL, thus supporting the view that increases in endurance capacity are largely the result of changes in the skeletal muscle rather than improvements in the central cardiovascular system. The findings of this study clearly demonstrate that VO2 max is a poor predictor of endurance capacity. It provides no information regarding an individuals ability to endure exercise, i.e. the ability to sustain a given submaximal work load, both before and after training. It is suggested that the fitness of an individual may be reflected not by their V02 max value but rather by the largest fraction of that value which he or she can utilize during prolonged periods of exercise.

High-intensity exercise results in hydrogen ion accumulation, which can have a deleterious effect on muscle function, and thus exercise tolerance. Buffering agents are commonly used to enhance exercise performance and capacity. Two such agents, β-alanine and sodium bicarbonate, increase intracellular and extracellular buffering capacity, which could contribute to an improved performance and capacity during exercise limited by increasing acidosis. Despite this, studies on the ergogenic effects of β-alanine are still in their infancy, and research on sodium bicarbonate remains equivocal. The aim of this thesis was to investigate the separate and combined effects of β-alanine and sodium bicarbonate on high-intensity exercise performance and capacity using various exercise modalities. The CCT110%, a cycling capacity test, was shown to be reliable (Chapter 4A), and subsequently employed to investigate the effect of sodium bicarbonate (Chapter 4B), β-alanine and co-supplementation of the two (Chapter 4C). Sodium bicarbonate supplementation was shown to improve total work done during the CCT110% (+4.8%), only when those experiencing gastrointestinal discomfort were removed from analyses, as was β-alanine (+14.6%); co-supplementation of the two did not confer any further benefits above β-alanine alone. Neither sodium bicarbonate (Chapter 5A) nor β-alanine or co-supplementation of the two (Chapter 5B) improved 5 x 6 s repeated running sprints (all P > 0.05). Sprint performance during the Loughborough Intermittent Shuttle Test was unaffected by β-alanine supplementation in elite (P = 0.63) and non-elite (P = 0.58) games players (Chapter 6), although YoYo Intermittent Recovery Test Level 2 performance was improved (+34.3%) with β-alanine in amateur footballers during a competitive season (Chapter 7). High-intensity match activities during competitive match play were unaffected by β-alanine supplementation (Chapter 8). The results in this thesis showed that β-alanine was effective at improving exercise capacity but not exercise performance. Results suggest sodium bicarbonate, and co-supplementation with β-alanine, may improve exercise tolerance although further research is warranted.

The benefits of physical activity for health are sufficient enough to be incorporated into UK public health policy and the exercise referral scheme is a popular method of engaging sedentary individuals into a more active lifestyle. However, the evidence base as to the extent to which such schemes impact upon holistic health outcomes is limited. This deficit is particularly apparent for psychological measures, despite these being reported as the most likely outcomes of a referral into exercise. The primary reason for this problem is the lack of tools available to exercise professionals with which to capture this valuable data. This thesis proposes that, in addition to the more commonplace monitoring of physiological outcomes and physical activity level, that psychological responses to, and outcomes of, a referral into exercise should be monitored as part of routine practice. The complete thesis provides an exercise referral sensitive quality of life measure, the Exercise Referral Quality of Life Scale (ER-QLS), which is intended for use in practice and/or for the purposes of research. Five stages of research were undertaken to produce the final measure. Two were qualitative and three were quantitative. Stage one utilised a series of five focus groups to generate rich data for the purposes of item development and a conceptual framework of exercise-related life-quality that would inform subsequent psychometric analyses. Stage two employed best-practice recommendations from previous research to construct test items and formulate a test measure that was formatted in such a way as to facilitate its completion and reduce respondent burden. Stage three cognitively pre-tested these test-pool items to ensure that they were interpreted as intended and to establish appropriate face and content validity. Stage four employed a classical testing theory approach to item reduction and also assessed the initial reliability of the measure through test-retest and internal consistency analyses. The final fifth stage employed a principal components and parallel analysis approach to exploratory factor analysis and assessed the internal consistency, test-re-test reliability, acceptability, content validity, and convergent and known groups components of construct validity of the final measure. The ER-QLS showed good reliability and validity, is easy to administer and to score. It is expected that the measure will encourage the monitoring of exercise-related life-quality within exercise referral settings as part of more holistic approaches to evaluation. The implications for wider policy and practice are also discussed.

Chapter 1 provides an introduction to the context in which four studies were conducted to assess how exercise impacts on nicotine addiction processes. Chapter two gives an overview of some contemporary theories of addiction and the possible processes underlying addiction. The second part provides details of chronic (intervention) and acute studies that have assessed the effects of exercise on cigarette cravings, smoking withdrawal symptoms and cue-reactivity. The findings will be discussed in terms of the type and duration of exercise utilised and the strength and duration of effects on subjective desire to smoke and cigarette cravings. Lastly, some possible mechanisms by which exercise may exert effect on cravings and cue-reactivity are identified. This background provides a basis for the subsequent studies. Chapter three describes an experimental study (Study 1), in which fMRI was used to compare brain activation response to smoking-related stimuli (compared with neutral stimuli) during nicotine abstinence and immediately following smoking a cigarette. The aim of this study was to pilot methods for future fMRI studies to assess the effects of a single session of exercise on brain responses to smoking-related images. Previous evidence has shown that during periods of deprivation, stimuli of perceived ‘salient’ importance (i.e. smoking-related images, such as images of people smoking) are associated with enhanced activation in areas of the brain known as the mesocortical-limbic circuit (i.e. nucleus accumbens, amygdala, hippocampus, prefrontal cortex, orbitofrontal cortex and anterior cingulate) (Due et al, 2002; David et al 2005; McClernon et al, 2005; Smolka et al 2006). Chapter four and five describe two further fMRI studies (Study 2 and 3). These two studies sought to investigate the effects of an acute bout of exercise on regional brain activation to smoking-related (compared to neutral) images. The first study (Chapter 4) uses an event-related design whereby smoking and neutral images were randomly presented during scanning. The second study (Chapter 5) employs a block design method, whereby individuals view a randomised block of either 3 smoking or 3 neutral images. Chapter six describes a study (Study 4) designed to examine the effects of an acute bout of exercise on attentional bias to smoking-related images. This study utilised an eye tracking methodology to compare duration of gaze and direction of fixation following a session of passive rest or acute exercise. Previous studies in this area (without the exercise session comparison) have demonstrated that’s smokers show enhanced gaze duration toward smoking stimuli (versus control cues or non smokers) (i.e. Mogg et al, 2005) and during nicotine deprivation (i.e. Field et al, 2004). Some studies have suggested these biases in attention may be associated with higher subjective cravings (i.e. Mogg et al, 2005; Field et al, 2009). All studies assessed the effects of exercise on subjective cravings to smoke. An overall summary of findings and discussion is presented in Chapter 8. The findings are conceptualised and integrated into existing theories of addiction, and ideas for future research are presented. The work presented in this thesis has been presented at both National and International conferences and is either published or is under review in peer review journals. Please see the footnotes at the start of each chapter for more details.

The contemporary training practices of powerlifters are presently being adopted by athletes from a variety of sports seeking to improve their performance. The aims of this PhD were to: 1) identify the contemporary training practices of powerlifters; 2) investigate the biomechanical stimulus the training practices create; and 3) assess whether the training practices have the potential to improve the athletic performance of general athletes The aims were achieved through the completion of five related studies. The first study employed questionnaires and interviews to indentify the contemporary training practices used by elite powerlifters. The results demonstrated that elite powerlifters used a wide variety of training practices, many of which would not have been attributed to the group based on previous literature. The practices were categorised based on their underlying mechanical principles so that the essential features could be investigated in the subsequent studies. A regression-based approach was used in the second study to identify the biomechanical variables associated with performance of common sporting tasks. Maximum force production, power, velocity and rate of force development (RFD) were shown to explain a large percentage of variation in performance of tasks such as sprinting, jumping and changing direction (adjusted R2 ranged from 0.43 to 0.86). These mechanical variables were then measured in a series of experimental studies to assess the potential of the contemporary powerlifting practices to improve athletes‟ physical performance. Assessments were based on a central paradigm in strength and conditioning that asserts that improvements in the ability to express biomechanical variables (e.g. force and power) are best obtained with training practices that maximise acute production of the same variable. Based on the categorisation of the mechanical principles underlying the assessed training practices, three experimental studies were conducted that investigated: 1) the practice of performing traditional resistance exercises at maximum velocity; 2) the effects of manipulating the external resistance through the use of variable resistance material (chain resistance) and an unconventional barbell (the hexagonal barbell); and 3) the effects of altering the movement strategy used to perform the squat. The results of the studies clearly demonstrated that each of the practices investigated could be used to substantially alter and in most cases enhance the biomechanical stimulus created. The practice of performing traditional resistance exercises at maximum velocity revealed that all key mechanical variables were significantly increased (p<0.05) compared with the standard practice of performing repetitions with a sub-maximum velocity. In addition, the results demonstrated that when performing a traditional resistance exercise such as the deadlift at maximum velocity, experienced resistance trained athletes could accelerate the load for the majority (75% to 90%+) of the movement. The second experimental study featuring the separate use of chain resistance and the hexagonal barbell to alter the characteristics of the external resistance demonstrated contrasting effects. The change in position of the external resistance when using the hexagonal barbell significantly (p<0.05) increased the participants' ability to produce high force, power, velocity and RFD values across a range of loads in comparison with the same movement performed with a traditional straight barbell. In contrast, the results from the study evaluating the effects of adding chain resistance showed that whilst force values were increased with the addition of chains, velocity, power and RFD values substantially decreased compared to standard repetitions performed with barbell resistance only. The results also demonstrated that the effects of the chain resistance were more noticeable with heavier chain and barbell loads. The final experimental investigated the effects of altering the movement strategy used to perform the back squat exercise. The results confirmed that changes to the movement strategy had a significant effect on a range of kinematic and kinetic variables. In particular, the contemporary techniques promoted by powerlifters resulted in substantial kinematic and kinetic changes at the hip and reduced kinetic output at the ankle joint. Collectively, the work from this PhD supports the selective use of contemporary powerlifting training practices for the development of athletic potential. Future research should build on the framework created in this thesis, progressing to longitudinal and ultimately implementation studies to increase the likelihood of transferring the results to practice.

Eating disorders pose long-lasting physiological and psychological consequences, and have one of the highest mortality rates amongst mental illnesses (Harris & Barraclough, 1998). In recent years, athletes have been frequently identified as at more risk of developing eating disorders, and problematic eating attitudes and behaviours than the general population (e.g., Sundgot-Borgen & Torstveit, 2004). Athletes with eating disorders not only risk compromising their performance, but also their health and general wellbeing (Currie & Morse, 2005). Therefore, the identification of the prevalence, as well as the potential factors that is likely to contribute to eating disorders in athletes present a valuable avenue for research. The first study of this thesis examined the prevalence of potential eating disordered cases amongst a sample of elite, developmental, and recreational British athletes, as well as a control group of British non-athletes. Gender and sport type differences between and within these aforementioned performance standards were also examined in this study. Results demonstrated that while recreational athletes and non-athletes reported greater disturbed eating psychopathology, there were no significant differences in the prevalence of probable cases of eating disorder between elite, developmental, recreational, and non-athletes. However, there was a trend for a higher number of non-athletes and recreational athletes (males and females, regardless of sport type) to be classified as potential cases with clinical eating disorders. In addition, a higher number of females from the elite and non-athlete performance standards were classified as eating disordered than their respective male counterparts. Thus, these findings provide evidence to suggest that eating disorders pose a cause for concern in less competitive athletes and those that do not engage in organised sport at all. Guided by the established maintenance factors associated with eating disorders within the general population (see Fairburn, Cooper, & Shafran, 2003), Studies 2 and 3 reflect a series of cross-sectional investigations aimed to test the association between a range of interpersonal difficulties and eating psychopathology. These studies were designed to fill the iv gap in the current eating disorder literature by examining multiple pathways between both situational (i.e., relationship quality with parents, coaches, and teammates) and dispositional interpersonal difficulties (i.e., attachment styles) and eating psychopathology via the mediating variables of perfectionism, self-esteem and depression. Mediational analyses in Study 2 revealed that relationship quality with parents and coaches as defined by social support, interpersonal conflict, and insecure attachment styles were indirectly related to athletes' eating psychopathology via the mediating roles self-critical perfectionism, selfesteem, and depression. However, the quality of relationship with teammates was not associated to athletes' eating psychopathology. Study 3 further examined the association between eating psychopathology and situational interpersonal difficulties (i.e., relationship quality with mother, father, and coaches), as well as dispositional interpersonal difficulties (i.e., social anxiety and loneliness) among a sample of athletes and non-athletes. Mediational analyses revealed that the quality of the relationship with the father, and levels of loneliness were indirectly related to athletes' eating psychopathology via the mediating role of depression, while social anxiety was found to be both directly and indirectly related (via depression) to athletes' eating psychopathology. In the case of non-athletes, the quality of the relationship with both the mother and the father, levels of social anxiety and loneliness were indirectly related to eating psychopathology via the mediating role of depression, self-esteem, and self-critical perfectionism. Furthermore, this study provided evidence to suggest that dispositional interpersonal difficulties may be more robust independent predictors of athletes' and non-athletes' eating psychopathology than situational interpersonal difficulties (i.e., relationship quality with significant others). Collectively these studies suggest that the psychosocial mechanisms hypothesised to be involved in eating disorders within the general population closely resemble that of athletes. Employing a prospective research design, Study 4 examined the predictive role of situational and dispositional interpersonal difficulties in athletes' eating psychopathology. Conducted over a 6 month period, the findings of this study revealed that only situational interpersonal difficulties as reflected in the quality of the relationship with coaches and teammates were associated to athletes' eating psychopathology, over and above their initial eating psychopathology. Moreover, the study highlighted interpersonal conflict within the coach-athlete relationship as the only independent predictor of athletes' eating v psychopathology. Therefore suggesting that conflict with the coach should be considered as a potential risk factor in the development of eating disorders amongst athletes. The final study tested the main constructs underlying the transdiagnostic cognitive behavioural theory of eating disorders (Fairburn et al., 2003) within an athletic population. Results revealed that elevated eating psychopathology may arise from an interaction of 'interpersonal difficulties', low self-esteem, high levels of self-critical perfectionism, and depressive symptoms. Moreover, findings of this study demonstrated that the tested model is invariant across athletes' sport type and performance standard, but not across gender. Thus suggesting that the psychosocial processes involved in eating disorders are the same regardless of the type of sport, and the performance standard that an athlete competes in. Overall, the findings of the current research revealed that while the prevalence of eating disorders may be considerably lower within the British athletic population than the general population, there is still cause for concern, given the high prevalence detected in recreational athletes, as well as the high number of competitive athletes engaging in inappropriate compensatory weight control behaviours (i.e., excessive exercise and selfinduced vomiting). Moreover, the results of the latter studies suggest that psychosocial factors are important and pertinent factors to consider in the aetiology of eating disorders amongst athletes. As a whole, this thesis makes a significant contribution to furthering our understanding of the prevalence and psychosocial correlates of eating psychopathology amongst British athletes.

Background: Despite known health benefits, the majority of children and adolescents do not meet recommended physical activity and sedentary behaviour guidelines. Amongst determinants of these behaviours, the influence of friends and peer groups remains largely understudied. In this thesis I investigated the influence of friends, peer groups and friendship network structure on physical activity and sedentary behaviours. Methods: Methods were drawn from a set of analytical tools known as 'Social Network Analysis', which use friendship nomination data, along with measures of physical activity and sedentary behaviour, to investigate the extent to which friendship network structure was related to the activity behaviours of individuals in the network. Results: There was strong and consistent evidence for similarities in physical activity and sedentary behaviour between friends and within friendship groups, both in children and adolescents. There was a positive correlation in physical activity behaviours between childhood friends, and the likelihood of friendship between two adolescents increased as their physical activity or sedentary behaviour became more similar. The extent of similarity in the behaviours between friends increased with age, and was strongest in late adolescence. Longitudinal analysis over a 7 year period indicated that friendship similarities in physical activity were partly explained by the influence of existing friends in changing an individual's behaviour, and partly by the selection of new friends with similar activity levels. In contrast friendship similarities in sedentary behaviour appear to be solely explained by selection of new similar friends, rather than the influence of existing friends. Conclusions: My findings indicate that friends and peer groups play an important role in shaping both physical activity and sedentary behaviour in children and adolescents, and that harnessing peer influence for behaviour change is a promising direction for future physical activity and sedentary behaviour interventions.

Introduction: Children in the UK from South Asian backgrounds have increased risk of metabolic disease, increased body fat and engage in reduced physical activity (PA) compared to White children (Ehtisthan et al., 2000, 2004; Whincup et al., 2002). The mechanisms underlying the lower physical activity patterns are not fully understood in South Asian children. Ethnic groups cluster in deprived areas within the UK (Jayaweera et al., 2007; Williams et al., 2009) and thus the role of the physical environment and how children use this environment for PA, needs exploring in order to increase PA through interventions. The overall aim of the thesis was to assess the association between environmental factors and PA behaviour in deprived South Asian primary school children. Methods: Following institutional ethical approval, children and their parents from two primary schools within deprived wards in Coventry were recruited. Objective assessments of PA (heart rate or pedometer, the physical environment (global positioning system)) and body adiposity (body mass index, waist circumference and body fat %) were obtained from children. Perceptions about the physical and social environment were obtained from focus group discussions with children and parents. The findings obtained from quantitative and qualitative evidence were combined to apply a multi-dimensional intervention increase PA in SA children from low SES environments. Results: Quantitative results identified that children are more active in outdoors environments (non-greenspace) (P <0.01), but that South Asian children spend more time indoors (P = 0.03) and are less active indoors (P = 0.04). Qualitative findings identified the importance of the supportive physical and social environment at school on children’s PA levels. Additionally, unsupportive physical (e.g. poor access, safety and quality) and social factors (e.g. anti-social behaviour) within the neighbourhood were identified as barriers to children’s outdoor play, resulting in sedentary behaviours indoors. The multi-dimensional intervention provides evidence that modifying the physical and social environment through school can increase PA. The results indicated that average daily steps were significantly higher in the intervention group at 6 weeks post compared to baseline and the control group (mean change ± SD of change = 8694 ± 7428 steps/day vs. -1121 ± 5592 steps/day, 95% CI of difference, 6726, 7428 steps/day, P = 0.001, d = 1.76). No significant change from pre to post 6 weeks was found for the control group (mean change ± SD of change = -1121 ± 5592 steps/day, 95% CI of difference = -1301, 3004 steps/day, P= 0.42). In addition, significant decreases in South Asian children’s body fat % (mean change ± SD of change = -4.46 ± 4.77% vs. -1.09 ± 2.77%, 95% CI of difference, -1.26, -0.34% , P = 0.001, d = 1.22) and WC (mean change = -1.73 ± 4.48cm vs. -0.21 ± 3.49cm vs. respectively, 95% CI of difference, -3.40, 0.36cm, P = 0.001, d= 0.44) were observed in the intervention group post 6 weeks compared to the control group. Conclusion: To conclude, the findings confirm the importance of social and physical environments on children’s PA patterns, which can be changed using an intervention to increase children’s PA. Further research needs to examine the long-term sustainability of an integrated school based curriculum intervention and the effects this has on metabolic risk.

Overweight and obesity are the fifth leading risk factors for global deaths. At least 2.8 million adults die each year as a result of being overweight or obese. In addition, 44% of the diabetes burden, 23 % of the ischemic heart disease burden and between 7% and 41 % of certain cancer burdens are attributable to overweight and obesity (WHO, 2011). Overweight and obesity, as well as their related non-communicable diseases, are largely preventable through the pursuit of regular physical activity. Existing research has identified social exercise and music, as two key factors in encouraging participation and adherence to traditional exercise however in the context of exergames this area remains largely unexplored. The aim of this research is to investigate the impact of both social exercise and music in exergames. There are three main studies in this research that explore the objective and subjective assessment of social exercise and music on performance and experience of exercise in an exergame context by concentrating upon the physiological measures, performance measures and experience measures. All of the studies use quantitative methodology; they employ a repeated measures design. The first study sampled thirty University students and assessed their exergame experience in three sound conditions: no music, experimenter-selected music and self-selected music. The second and third study sampled twenty-six University students and assessed their exergame experience in the three aforementioned sound conditions as well as examining the impact of exercising with a friend in a co-located (study 2) and spatially separated setting (study 3). Results suggest that listening to music can facilitate exercise and exercise with a friend in a co-located setting can lead to greater performance and experience.

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