<p><font face="Times New Roman" size="3"><font face="Times New Roman" size="3"> <p align="left">This thesis is a discourse analysis of five testimonies from South Africa&rsquo / s Truth and Reconciliation Commission. The aim of the analysis is to explore the ways in which the testifiers perform their identities, construe their experiences of life under apartheid, and position themselves and their audiences in relation to these experiences. The shaping role of context &ndash / both local and historical &ndash / is also considered.</p> </font></font></p>

Introduction: Concussions are a physiologically & psychologically stressful event. Stress markers may provide insight into concussion recovery, but have not been examined. Purpose & Method: To investigate the stress response of concussed athletes compared to controls from injury to post-RTP. Concussed athletes’ Mood states, Perceived Stress, HRV, and Morning & Afternoon Cortisol were assessed at 3 phases of recovery following concussion. Results: Repeated measures ANOVA revealed significant interactions for TMD, Depression, Anger, Confusion, Fatigue, HF norm (rest), LF norm (rest), HF norm (difference between sitting & standing), LF norm (difference between sitting & standing), and LF/HF ratio (difference between sitting & standing). Vigor & Tension demonstrated significant changes over time in the concussed group. Significant difference between the two groups for morning Cortisol levels at phase 3 was revealed. Conclusion: Concussed athletes display elevated levels of stress post-injury. Findings warrant further investigation of stress markers in concussed athletes during recovery.

Introduction: Concussions are a physiologically & psychologically stressful event. Stress markers may provide insight into concussion recovery, but have not been examined. Purpose & Method: To investigate the stress response of concussed athletes compared to controls from injury to post-RTP. Concussed athletes’ Mood states, Perceived Stress, HRV, and Morning & Afternoon Cortisol were assessed at 3 phases of recovery following concussion. Results: Repeated measures ANOVA revealed significant interactions for TMD, Depression, Anger, Confusion, Fatigue, HF norm (rest), LF norm (rest), HF norm (difference between sitting & standing), LF norm (difference between sitting & standing), and LF/HF ratio (difference between sitting & standing). Vigor & Tension demonstrated significant changes over time in the concussed group. Significant difference between the two groups for morning Cortisol levels at phase 3 was revealed. Conclusion: Concussed athletes display elevated levels of stress post-injury. Findings warrant further investigation of stress markers in concussed athletes during recovery.

Master of Science / Department of Human Nutrition / Mark Haub / The purpose of this review is to examine the role of heart rate variability (HRV) as a predictor of athletic readiness and performance and assess whether nutrition strategies can be implemented to create favorable HRV indices with the goal of improving athletic readiness and performance. The balance between training and recovery is crucial for reaching an optimal adaptation and avoiding overtraining, allowing for improved readiness to train and compete. The measurement of HRV is non-invasive and is used primarily to quantify physical and mental stress in athletes by monitoring the effects of the autonomic nervous system on the heart. Current data suggests a relationship between resting parasympathetic tone, via time and frequency domains, and athletic performance. Parasympathetic modulated HRV indices have been associated with performance metrics such as peripheral work capacity, aerobic power, running and sprint performance, swimming performance, weight lifting performance, anaerobic capacity, strength, and enhanced mental focus/skill execution. The use of nutrition to help enhance sports performance is becoming more common. Evidence-based sports nutrition provides fuel for training/competition, assists in maximizing training adaptations, enhances recovery, improves mental focus, and aids in injury prevention and recovery. The use of nutrition strategies to influence HRV is novel and current evidence is scarce in regards to nutritional effects on HRV, specifically in athletes. Current research suggests that achieving energy balance and decreasing body fat in overweight/obese individuals has positive effects on the vagal component of HRV indices. Proper hydration, fruit and vegetable intake, a moderate carbohydrate diet, omega-3 fatty acid supplementation/intake also seem to have positive effects on HRV indices. Certain individual supplements have been studied in regards to HRV including casein hydrolysate, amaranth oil, and bovine colostrum. Caffeine seems to have the opposite effect on HRV indices, increasing sympathetic modulation while decreasing parasympathetic modulation. Much more research needs to be done in regard to potential nutritional influences on HRV so that sport dietitians feel confident in the methods currently used to assess athlete readiness and determining what types of nutrition strategies may be used to further improve the performance of an athlete.

Wellbeing and subjective wellbeing (SWB) has become some the most important goals of our time, both individually and societally. Thus, there is a need for reliable ways to measure SWB, as concerns regarding many current measures have been raised. Due to the interwoven nature of physiology and psychology, heart rate variability (HRV) has the potential to assess psychological processes in a physiological manner. HRV is an attractive measure since it is inexpensive, easy and non-invasive. Hence, the aim is to, from a cognitive neuroscientific standpoint, investigate whether HRV could serve as an objective measure to assess SWB. Most studies demonstrate associations between HRV and SWB, in particular between high frequency (HF)-HRV and positive affect (PA). However, the one study fully matching the theoretical framework only showed an inverse correlation between HRV and negative affect (NA). Plausibly implying that HRV does not serve as a reliable measure of SWB, but may be able to indicate inverse associations with NA, and possibly index certain aspect of SWB such as deactivated PA. The study of the relationship between HRV and SWB is still in its infancy and results are inconsistent. The lack of common standards regarding measurements, implementation details, and variable values, make results difficult to compare and generalize. Further standardizations and research are much needed before accurate conclusions can be drawn.

Made available in DSpace on 2014-06-11T19:23:45Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-02-23Bitstream added on 2014-06-13T20:51:01Z : No. of bitstreams: 1 pereira_ez_me_jabo.pdf: 262492 bytes, checksum: 9be8063c009d87911f7792e38907fec9 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Com o objetivo de investigar a importância de ferramentas que possam identificar as arritmias ou detectar seus possíveis fatores desencadeantes em portadores da cardiomiopatia arritmogênica do ventrículo direito, 25 cães Boxers foram submetidos ao exame eletrocardiográfico convencional (ECG) e variabilidade da frequência cardíaca (VFC), obtida pela avaliação Holter de 24 horas, e 20 foram submetidos ao exame eletrocardiográfico de alta resolução (ECGAR). Os cães foram divididos em três grupos de acordo com o número de extrassístoles ventriculares (EV) obtidas pela avaliação Holter. O GC foi composto por cães apresentando menos de 20 EV/24 horas, o GD1 foi formado por animais com mais de 100 e menos de 1.000 EV/24 horas, enquanto o GD2 foi composto por animais que apresentaram mais de 1.000 EV/24 horas. Levando em consideração a presença de EV e extrassístoles supraventriculares (ESV) no ECG, este teste apresentou 83,33% de sensibilidade, 100% de especificidade, valor preditivo positivo (VPP) de 100% e valor preditivo negativo (VPN) de 86%. Os parâmetros da VFC SDNNIDX (Gc: 194,08 ± 56,29 ms; GD1: 202,20 ± 94,79 ms; GD2: 118,00 ± 43,76 ms) e pNN>50 (Gc: 39,75 ± 12,69 ms; GD1: 46,24 ± 14,08; GD2: 21,52 ± 9,27 ms) foram significativamente menores nos pacientes do GD2. O ECGAR apresentou sensibilidade de 30%, especificidade de 50%, VPP de 37,5% e VPN de 41,67%. Assim, os resultados sugerem que a eletrocardiografia convencional e a VFC são técnicas que podem contribuir substancialmente no diagnóstico da CAVD em cães Boxers, ao contrário da eletrocardiografia de alta resolução que se mostrou ineficaz em identificar a presença de potenciais tardios nos pacientes com esse grau de doença / Aiming to investigate the importance of tools that could identify arrhythmias or detect its possible inciting factor in patients affected by arrhythmogenic right ventricular cardiomyopathy, 25 Boxer dogs were submitted to conventional electrocardiogram (ECG), heart rate variability (HRV), obtained by 24-hours Holter evaluation, and 20 were submitted to high resolution electrocardiogram (HRECG). Dogs were divided into three different groups according to the number of ventricular complexes (VC) obtained in Holter analysis. The GC was formed by dogs presenting less than 20 VC/24 hours, the GD1 was formed by animals presenting more than 100 and less than 1.000 VC/24 hours, while the GD2 was composed of dogs presenting over a 1.000 VC/24 hours. Considering the presence of ventricular or supraventricular complexes on the ECG, this test had 83,33% of sensitivity, 100% of specificity, positive predictive value (PPV) of 100% and negative predictive value (NPV) of 86%. The HRV parameters SDNNIDX (Gc: 194.08 ± 56.29 ms; GD1: 202.20 ± 94.79 ms; GD2: 118.00 ± 43.76 ms) and pNN>50 (Gc: 39.75 ± 12.69 ms; GD1: 46.24 ± 14.08; GD2: 21.52 ± 9.27 ms) were significantly lower in the patients of GD2. The HRECG showed 30% of sensitivity, 50% of specificity, PPV of 37,5% and NPV of 41,67%. Thus, the results suggest that conventional ECG and HRV are techniques that can strongly contribute in the diagnosis of ARVD in Boxer dogs, opposed to HRECG that showed itself inefficient to detect the presence of late potentials in patients with this degree of disease

There were two main objectives of this thesis. First, given that personality traits have been linked to a number of diabetes risk factors and precursors such as lifestyle and the metabolic syndrome, our aim is to explore whether personality traits are associated with type 1 and type 2 diabetes mellitus. Second, we aim to investigate several potential mechanisms by which personality could influence diabetes, and other health outcomes such as cardiovascular disease and mortality. Chapter 1 provides an introductory overview of the history of personality-health research, and discusses strengths and limitations of different methodological frameworks. Chapters 2-4 focus on the associations between personality and diabetes. Two studies described in Chapter 2 examine cross-sectional and longitudinal associations between personality and type 1 and type 2 diabetes. We used a large national sample with ten years of follow-up. We detected positive associations between openness and neuroticism and type 1 diabetes prevalence, and negative associations between neuroticism and type 2 diabetes incidence. In Chapter 3, we examine relationships between personality and type 2 diabetes incidence using aggregated personality and diabetes data on a level of the U.S. counties and states. In a six-years follow-up study, we found no evidence that mean levels of personality traits were associated with diabetes incidence in the U.S. states. In the following chapter we explore whether a possible mechanism by which personality may influence diabetes is by moderating the expression of its genetic risk. The study described in Chapter 4 looks at interactions between personality domains and facets with polygenic risk score for type 2 diabetes in predicting glycated haemoglobin levels using a large community-dwelling sample. This study found a negative phenotypic correlation between openness and glycated haemoglobin levels, though this association was confounded by cognitive ability. Moreover, genetic risk for diabetes was more strongly associated with glycated haemoglobin levels in people with lower levels of either agreeableness or conscientiousness. In Chapter 5 we move away from diabetes to discuss previously reported contradictory results regarding the effects neuroticism has on mortality. Some of the previous studies reported higher neuroticism being associated with higher risk of mortality, whereas some reported that higher neuroticism was associated with lower risk of death. We tested whether the sign of the neuroticism effect was a function of the covariates included in the models. In a national sample with ten years of follow-up we found that neuroticism was a risk factor for death in the models that did not include objective and self-rated health variables. However, when these variables were included, neuroticism was related to lower risk of death. In the last empirical chapter, Chapter 6, we explore whether autonomic nervous system activity is a biomarker for personality traits. The first study tests whether openness is associated with measures of sympathetic and parasympathetic nervous system activation. We find that openness was associated with sympathetic nervous system activity under baseline but not in the stress conditions, and that it was not associated with measures of parasympathetic activation. The second study describes a model of associations between neuroticism and autonomic nervous system activation, while controlling for cardiovascular disease and depression and their mutual associations. We found that neuroticism has independent contributions to all measures of autonomic nervous system activity, and to heart disease, even when controlling for relevant clinical variables. Thus, autonomic nervous system activity may explain in part observed links between personality, and heart disease and mortality. Finally, in Chapter 7 we summarize the findings presented in the five empirical chapters, discuss the limitations of the current method, and offer suggestions for future research in the field.

Philosophiae Doctor - PhD / This thesis is a discourse analysis of five testimonies from South Africa’s Truth and Reconciliation Commission. The aim of the analysis is to explore the ways in which the testifiers perform their identities, construe their experiences of life under apartheid, and position themselves and their audiences in relation to these experiences. The shaping role of context – both local and historical – is also considered.

L'analyse de la Variabilité de la Fréquence Cardiaque est une méthode de mesure non invasive du Système Nerveux Autonome. Cette méthode d'analyse initialement utilisée dans le domaine clinique s'est progressivement installée dans le domaine de l'activité physique pour diverses applications telles que la détection précoce de la fatigue, le calibrage de l'intensité de l'entraînement, détecter les seuils ventilatoires... Les méthodes d'analyse peuvent être utilisées hors contexte de laboratoire, mais nécessitent néanmoins une attention particulière du point de vue méthodologique pour être cohérentes vis-à-vis des concepts mathématiques ou physiologiques qui les régissent. Chaque étape de cette méthode nécessite une rigueur spécifique pour ne pas conduire à une mauvaise interprétation. Ce document détaille le processus depuis la phase de mesure de l'intervalle RR en étudiant notamment la précision des appareils utilisables sur le terrain ou la correction du périodogramme obtenu en proposant différentes méthodes. Ce travail décrit également les indices de l'analyse de la VFC et les différentes limites techniques et conceptuelles. Les différents facteurs et biais influençant l'état du tonus du Système Nerveux Autonome seront décrits pour faciliter la création d'un protocole et l'analyse des indices de la VFC obtenus. / Heart Rate Variability Analysis is a non-invasive method for the evaluation of the Autonomic Nervous System activity. This analytical method initially used for clinical diagnosis progressively installed in the field of physical activity for various applications such as early detection of overreaching, calibration of training intensity, ventilatory threshold determination... These methods can be used outside the laboratory environment, but still require particular attention from a methodological aspect in order to be consistent with mathematical or physiological concepts underlying. Each step of this method requires a specific discipline not to lead to misinterpretation. This document details the process from the RR interval measurement phase including accuracy assessment of the devices used in the field or signal treatment with artifacts correction proposing several methods. This work details index from HRV analysis with their technical and conceptual limitations. External factors mat influence the Autonomic Nervous System are described to facilitate the protocol creation and results interpretation

Biofeedback equipment is intended to train conscious regulation of normally sub-conscious processes like autonomic nervous system activities. The manufacturers claim that measurements made with the equipment are accurate enough for research purposes, but these claims have not been vigorously tested. The subconscious processes recorded with biofeedback equipment are often disturbed by stress, and the aim of this study was to determine if the markers of stress could be accurately determined with biofeedback equipment. The physiological processes that were screened were:<ul><li> Time and frequency domain heart rate variability (HRV) determined from blood-volume-pulse (BVP) </li><li> Time and frequency domain HRV determined from electrocardiogram (ECG) </li><li> The amplitude of the BVP</li><li> Electromyographic (EMG) activity</li><li> The pulse transit time</li><li> Respiration rate and depth</li><li> Skin conductivity</li><li> Fingertip temperature</li><li> Quantitative electroencephalographic (QEEG) activity</li></ul> The accuracy of the HRV measurements were tested by comparing them to readings made simultaneously with a gold-standard device (Actiheart), and the main findings were:<ul><li> The hardware capabilities of the two systems are comparable when it comes to registering heartbeats and calculating heart rate</li><li> The frequency domain biofeedback HRV variables had relatively good correlations to the Actiheart results, but improvements are necessary</li><li> Frequency domain HRV variables differ when calculated with fast Fourier transform or with autoregression</li><li> The BVP signal is prone to movement artifact and other forms of interference</li></ul> The HRV measurements of both the biofeedback and Actiheart device were correlated to psychometric evaluations of anxiety and burnout, two conditions closely related to the concept of stress. The main findings were:<ul><li> Worry and anxiety can have a cardiac accelerating effect, largely mediated by vagal withdrawal </li><li> A decrease in resting autonomic variability associated with anxiety</li><li> Significant autonomic nervous system inflexibility occurs in the face of a cognitive stressor with increased anxiety</li><li> An increase in vagal and a decrease in sympathetic cardiac control correlated with increased levels of vital exhaustion</li><li> HRV assessment with specialized software such as Polar Precision Performance Software and the advanced HRV Analysis 1.1 software for windows (Biomedical Signal Analysis Group) were superior to assessments by means of the Biograph Infinity program</li></ul> Next it was investigated whether any association existed between levels of anxiety, burnout and that of Biograph-derived physiological indicators such as BVP amplitude, BVP HRV, ECG HRV, pulse transit time, EMG, fingertip temperature, respiration rate and amplitude, skin conductivity and QEEG levels. The overriding observations with increases in the levels of stress-related emotional conditions such as anxiety were that of a decrease in variability in almost all physiological functions assessed by Biograph. In conclusion, relatively good associations were found between certain, but not all, Biofeedback monitor results and that of other assessments of stress. The potential exists to develop a program which would accurately reflect stress levels. / Dissertation (MSc)--University of Pretoria, 2012. / School of Health Systems and Public Health (SHSPH) / Unrestricted