The human right to health extends to the last few decades of life and we have a societal duty to ensure that older adults are supported to live their lives free from pain, suffering, and disability. Evidence suggests that physical activity can improve physical function and self-reported disability, therefore identifying an intervention that may be effective in changing this behaviour is imperative. This doctoral project adds to the emerging literature in this field by presenting the results of a meta-ethnography of qualitative studies and generating a theory about how physical activity can help older adults adjust to the ageing process and thus increase the chances of successful and healthy ageing. Moreover a theory-based physical activity intervention for older adults at risk of disability was tested in a feasibility study and pilot randomised controlled trial. This intervention was based upon self-determination theory and extended work undertaken in younger adults with depression. The appropriateness of the intervention and the theory is discussed in the context of the findings of the feasibility study and the meta-ethnography. It is feasible to recruit and deliver a randomised controlled trial of an intervention of this nature in this population. However, the findings of the process evaluation suggest there are elements of the programme theory that should be modified before this is undertaken. Important characteristics of the relationship between older adults and physical activity decisions, revealed by the meta-ethnography, should be used to tailor and optimise the programme theory before proceeding to further evaluation.

This thesis investigates the nature of ‘the self’ modern yoga practitioners cultivate. This ontological question is further divided into three sub-questions to find the answer stepby- step. They are: (1) How yoga practice influences practitioners' health and wellbeing; (2) How yoga practice influences the management of life crises; (3) How yoga practice influences the ‘sense of self’. Modern yoga in the West has been expanding rapidly after the Second World War, and the last 15 years in particular show an exponential growth. Although the numbers are hard to estimate, there were reportedly over 2.5 million practitioners in Britain alone in 2004 (Singleton, 2008). Similar numbers of yoga practitioners were reported in other countries (Strauss, 2004). However, the modern form of yoga practiced in Britain is not the same as the Indian traditional form of yoga. In Britain, the British Wheel of Yoga (BWY) officially represents the majority of the yoga population. This study has used hermeneutic phenomenology, chiefly that of Heidegger and of Merleau-Ponty, as a research methodology, because it enabled the researcher to understand the subjective lived experiences of modern yoga practitioners. For data collection, 15 in-depth interviews of BWY members, selected using the snowballing and theoretical methods, were carried out. Through analysis, six major themes emerged. They were: ‘Health and Well being’; ‘Management of Life Crises’; ‘Sense of Self and Yoga Development’; ‘CAMs & GPs’; ‘Relationships’; ‘Spirituality’. Following the analysis of the main themes, I explored the meaning of ‘the self’, and discussed it from two points of view: the inner-self arisen from embodied practice of yoga through relaxation and bodily proprioception, and the outer self situated in-theworld in relation with other people, which was captured as social self, and considered from various dimensions such as language and ideology, BWY lineage, globalization and commercialism. In a nutshell, this study found that ‘the self’ for the BWY practitioners was embodied, health orientated and secular. ‘The self’ of yoga was further compared and contrasted with four self development models: Patanjali’s Yoga Sutra; Maslow’s Hierarchy of Human Needs; Dreyfus/Merleau-Ponty’s Skill Acquisition model and The Ten Oxherding Pictures of Zen Buddhism. Lastly, the value of yoga for public health was explored using the anthropological idea of dis-ease. This study found that yoga’s therapeutic usefulness mainly came from ‘empowerment’, providing practitioners with yoga skills to take control of their own body and health.

This study was conducted in response to the low levels of physical activity in young people in the UK (and elsewhere) that are considered a major public health challenge. Adopting a critical ethnographic approach, this study explores how physical activity fits into the daily lives of young people (13-21-year-olds) from two youth centres in an urban area of Northern England. This approach enabled the exploration of young people’s physical activity perceptions and practices within the context, complexities, and contingencies of their wider lives, rather than as a compartmentalised phenomenon. Drawing on recent re-conceptualisations of the life-course and anthropological theories of childhood, I show that changes in physical activity over time were enmeshed within life-phase expectations and experiences, but were also non-linear and contingent. Social expectations of adolescence limited some young people’s physical activity practices, and yet many etched out ways of being mobile and physically active, including re-living childhood games on the streets, parks, and at youth centres. Employing spatial theories, I explain how the young people negotiated their sense of safety in their local environments in order to be mobile; created places of their own for sociality; and used spaces and props in the material environment to engage in informal physical activity practices such as “hardcore parkour”. I lastly use Foucauldian and gender theories to re-think how understandings and practices of physical activity were gendered, and centred around the self and the body’s appearance and capability. Many of the young men in particular engaged in ‘self-bettering’ practices: some took up boxing to deal with challenges in their lives and some shaped muscular, fit, and ‘healthy’ bodies. This thesis critically challenges the dominant discourses that shape young people’s individualistic understandings of themselves, their lives, and their physical activity practices. Engaging closely with the young people’s actions and experiences helps to reveal how the socioeconomic and material environments, that young people negotiate in daily life, interact with their physical activity and mobility practices.

The primary aim of this investigation was to examine experimentally the systemic stress effects produced by systems used to support the body in sedentary tasks. In the main experiment subjects were required to carry out a simple reading and writing task, for three hours, under two conditions. In one (T1) condition subjects were provided with a sedentary support and work surface arrangement which represented an average, dimensionally, of those found in offices. In the other condition (T2) a sedentary support-work surface configuration was individually fitted to each subject in conformity with ergonomics principles. The effects of the treatments were compared using the following: (a) biochemical responses, including total white cell and eosinophil blood counts, and urinary corticosteroid determinations; (b) visual and postural behaviour; (c) subjective comfort response; and (d) performance at the reading and writing task.

Health-harnessing physical activity has been traditionally been conceptualised in terms of moderate to vigorous intensity with a recommendation to undertake 150 minutes per week of moderate to vigorous activity forms the basis for many interventions or promotion efforts. Recent advancements in the measurement of physical activity however reveals that other dimensions can incur profound health benefits such as an increase in energy expenditure or a reduction in sedentary time. Excitingly, we now have the technology to capture and present personalised visual feedback across the multiple physical activity dimensions, which could theoretically help individuals change their behaviour by providing them with more options or solutions that can be aligned to the individual’s needs, barriers and preferences. The aim of this thesis was to develop a visual presentation of multidimensional physical activity behaviour and evaluate its efficacy as a tool to support behaviour change. Firstly, a laboratory validation concluded that the BodyMedia Mini was a valid and reliable option for capturing a presenting multidimensional physical activity. Secondly, a number of visual representations were developed from minute-by-minute physical activity data captured by this monitor. Step three was to pilot these graphical depictions to group of patients and health professionals during one-to-one, semi-structured interviews who provided evidence that the design and message was clear, informative and motivating. Secondary analysis of this data suggested this was particularly true of individuals with a low physical activity status for which the personalised multidimensional feedback served to evoke strong and persuasive cognitive and emotional responses. The final steps were to test the efficacy of this approach in two multi-component, exploratory randomised controlled trials. Trial one was conducted on patients identified as at-risk (n=204) and showed that trainer led self-monitoring of multidimensional feedback had a minimal impact on behaviour. Trial two was conducted on individuals declaring themselves as inactive (n=51) and showed that using multidimensional feedback along with real-time self-monitoring appears an effective strategy for behaviour change.

Part 1 Study 1: Effect of Sample Frequency and Filter Frequency on the Approximate Entropy Values for Isometric Force Records ApEn has been used to quantify signal complexity in isometric contractions and distinguish between patient groups. Sampling frequencies, ‘r’ values (a parameter needed in the ApEn algorithm which essentially accounts for the noise in the signal Pincus1991 and filters may affect signal characteristics reflected in an alteration in ApEn values and subsequent patterns of results. However there is little standardisation of such procedures for this measure. The purpose of the was to investigate the effect of the choices on ApEn values. While the ‘true’ ApEn value cannot be known the approach taken here was to start with the highest resolution signal and to identify the pattern of ApEn results across different percentages of maximum voluntary contraction and then assess the effect of the post-processing changes on this pattern. The results show the choice of sample rate and ‘r’ is critical in reliably determining changes in ApEn with effort level. It is suggested that ‘r’ used should be, if possible, a measured estimate of noise, sample rates should be as high as possible and filter cut-offs should not be lower than [40]Hz. Study 2: Effect of Bimodal Stimulus on Force Control of Elderly and Young Adults Research shows that older adults often exhibit reduced irregularity in force signal data during isometric contractions (e.g. Sosnoff2006). The purpose of this study was to examine magnitude of variability and structure of isometric force data using appropriate post-processing methods previously established in Study 1. Differences in structure of force output between old and young adults may be as a result of older adults having reduced visuomotor processing capabilities, therefore a second purpose was to assess this by providing three different types of stimuli: 1) audio 2) both audio and visual (bimodal) 3) visual. Young (18-25) and old (65-72) neurologically healthy adults produced isometric force contractions using abduction of the FDI at six force levels (5,10, 25, 40, 50 and 75% MVC) during each of the three conditions. There were no differences found in magnitudes of variability between the age groups nor was there any alteration in force output in the bimodal condition compared to the visual condition for either of the groups. The audio condition altered all indexes of force structure and variability significantly. ApEn values were significantly higher in younger adults at force levels > 25% MVC during all conditions indicating higher irregularity than older adults (mean across all conditions and force: old=0.15, SD 0.11 young=0.19, SD 0.13). These results support the postulation that reduced complexity occurs with ageing. As the force signal is more pattern like it may result in a reduced ability to alter force production when required leading to a lower level of functionality. Study 3:Decreased ApEn values in older adults are associated with increased time to achieve steady muscle force following a change in required force. It was hypothesised that lower ApEn values would be associated with a reduced ability to adapt to a required force change. ApEn of the force signal, functional reaction time, and time to reach a steady state at the new force target was measured. Two different types of stimulus were presented to participants as force targets, bimodal and visual. Young (18-25) and old (65-72) neurologically healthy adults produced isometric force contractions using abduction of the FDI at six force levels that either increased, or decreased at a random interval. Increasing force levels were 5 to 25%, 25 to 50% and 25 to 75% of MVC and decreasing force levels were 25 to 5%, 50 to 25% and 75 to 25% of MVC. Confirming our hypothesis, older adults exhibited longer times to reach steady state, even after removal of reaction time at force levels initiated above 5% MVC. Mean time to reach steady state (minus reaction time) was [2.83]s for young subjects and [3.23]s for old adults [t=2.14, p=0.03]. These results did not differ whether force target moved up or down. These results provide evidence to support the concept that reduced irregularity leads to decreased adaptability to task alterations. This knowledge may be beneficial when modelling ageing movement and force production or used as a pre-clinical tool for identifying those at risk of falls etc. Part 2 Study 4: The determination of Body Segment Inertial Parameters of young female club level athletes Body segment inertial parameters (BSIPs) must be determined to perform biomechanical analyses. Geometric BSIP models are cost effective, yet collecting the anthropometric data necessary is time consuming and time with athletes is often limited. Also, few anthropometric models have been validated for female athletes. The purpose of the study was to validate a geometric model for female club and college athletes. A total of 118 anthropometric measurements were taken from thirty female participants. The upper arms, forearms, hands, thighs, shank and feet were each modelled using four shapes per segment in the full model, and two shapes per segment in the reduced model. The trunk segment was modelled as a series of ten stadium solids in both models. Further refinements of the present model addressed the shoulder area reducing overlap of trunk and upper arm segments. The geometric model predicted segment volume and which was multiplied by cadaver derived density functions Clauser1969 to determine segment mass. The root mean square error between actual whole body volumes (WBV), determined using a hydrostatic weighing tank, and predicted WBV was 2.37%, 3.03% and 2.34% of WBV for the full, reduced and basic models respectively. The model predicted trunk mass with RMSE of just 3.49% of segment mass compared to DXA measured trunk mass. Pearsons correlation showed high correlation between the segment masses predicted by the full model and DXA measured mass [r values ranged from 0.727-0.893, p < 0.001] for the upper arms, forearms, thighs, shanks and feet. The full and reduced model showed high correlation for all segments [mean r=0.9100, p < 0.001] which confirms that reducing the number of anthropometric measurements taken from the limb segments (reducing required measures from 118 measures to 94) causes little difference in the predicted mass for limb segments. These results are of interest to sports biomechanists who are without access to direct imaging techniques, but who wish to compute subject specific BSIPs.

The importance of post-exercise recovery nutrition has been well described in recent years leading to its incorporation as an integral part of training regimes in both athletes and active individuals. Muscle glycogen depletion during an initial prolonged exercise bout is a main factor in the onset of fatigue and thus the replenishment of glycogen stores is central for post-exercise recovery. Nevertheless, nutritional recommendations, particularly related to the precise nutrient amount/type to optimise short-term (2-6 h) recovery remain incompletely elucidated. Furthermore, the available nutritional guidelines to maximise muscle glycogen availability within limited recovery are provided under the assumption that similar fatigue mechanisms (i.e. muscle glycogen depletion) are involved during a repeated exercise bout, yet this has never been established. One strategy with the potential to accelerate muscle glycogen resynthesis and/or functional capacity is the co-ingestion of protein with carbohydrate. Notwithstanding this, there is outstanding need to establish the influence of carbohydrate-protein ingestion on recovery from running exercise. Beyond the acute post-exercise period, protein ingestion following exercise is known to increase muscle protein synthesis and thus modulate exercise-induced training adaptation. However, whether post-exercise protein ingestion increases the magnitude of running-based endurance training adaptation has not been determined. The collection of work presented in this thesis provides evidence that the availability of muscle glycogen at the end of recovery determines the capacity for repeated exercise such that muscle glycogen depletion is shown to be a major determinant of fatigue during this bout. Moreover, the present work suggests that energy intake per se and not macronutrient composition (i.e. the addition of protein) determines maximal muscle glycogen resynthesis rate and the capacity for repeated exercise. The final experimental chapter in this thesis also provides some evidence for the potential role of post-exercise protein ingestion in amplifying cardiovascular training adaptation through an increase in plasma albumin content in response to six weeks of prescribed endurance training when compared to an energy-matched carbohydrate supplement.

The purpose of this thesis was to explore the motivational processes that underpin adolescent exercise and sedentary behaviour. Grounded in Self-determination theory (SDT; Deci & Ryan, 1985), a series of four studies sought to address key methodological pitfalls within the extant SDT literature and utilise these developments to explore how motivation and its related cognitive processes relate to adolescent exercise and sedentary behaviour. In Chapter 2, through focus groups with 39 adolescents, the participants’ conceptualisation of exercise was explored to inform the interpretation of responses to exercise-related measures and the measurement of exercise behaviour. In Chapter 3, to facilitate the holistic measurement of need support, the Adolescent Psychological Need Support in Exercise Scale (APNSEQ) was developed and validated in two samples of adolescents (N=806). In Chapter 4, applying the new APNSEQ measure and the conceptual insight gained in Chapter 2, cross-sectional data from 388 adolescents supported the nomological network of variables proposed within SDT. However, the SDT model only explained a small amount of variance in behaviour. Thus, in Chapter 5 (N=257), a mediation model, where action planning, self-monitoring and habit mediate the relationship between autonomous motivation and behaviour was explored. Habit was a significant mediator of the relationship between autonomous motivation and exercise and sedentary behaviour, and need support was indirectly associated with self-regulation. Collectively, the four studies address some key conceptual and methodological issues present in the extant SDT literature, and apply these developments to offer a comprehensive exploration of the motivational processes that underpin adolescent exercise and sedentary behaviour. Through holistically considering the antecedents of motivation (i.e., need support, need thwarting, need satisfaction, and need frustration), as well as exploring the processes through which motivation influences behaviour, this thesis offers exciting routes for theoretically robust future research, as well as potential insights for intervention.

There are clear recommendations regarding the amount of physical activity necessary for achieving health benefits and reducing the risk of chronic disease in able-bodied humans. However, there is a paucity of empirical evidence to inform the development of equivalent guidelines for various disabled populations. In order to better understand the role of physical activity in the health and wellbeing of wheelchair users, the logical foundation was to develop valid and reliable methods to accurately quantify physical activity. Therefore, the initial aim of this thesis was to assess the validity of objective wearable technologies in the prediction of physical activity energy expenditure (PAEE). Chapter 3 identified the wrist as the most appropriate anatomical location to wear a tri-axial accelerometer during outdoor wheelchair propulsion. In Chapter 4, a device comparison study was conducted in a controlled laboratory environment, using bespoke PAEE prediction equations, developed for this population. Mean absolute error for devices worn on the wrist were lower for the GENEActiv (21%) device compared to GT3X+ (33%), across all activities. Using a multi-sensor Actiheart device, the absolute prediction error was further reduced when an individual heart rate calibration was applied (16.8%), compared to a generic system calibration (51.4%) (Chapter 6). Incorporating accelerometry and physiological signals with individual calibration seemingly offered an improvement in the prediction of PAEE in wheelchair users. This rigorous method development process permitted the habitual monitoring of free-living physical activity behaviour, during a home-based moderate-intensity exercise intervention in persons with chronic paraplegia. In comparison to a lifestyle maintenance control group, the intervention group completed a 6-week arm crank ergometry intervention, exercising 4 times per week for 45 minutes at 60 – 65% V̇O2 peak. The intervention improved fasting markers of insulin resistance, increased fasting fatty acid oxidation, and cardiorespiratory fitness. There were also positive changes in health and wellbeing constructs and an excellent compliance rate. Hence, home-based upper body exercise may have the potential to be used as a long-term behavioural strategy to improve the health and wellbeing of persons with chronic paraplegia.

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