3. Electronic Theses and Dissertations (ETDs) - All submissions
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Item A comparison of exercise endurance levels between children diagnosed with developmental co-ordination disorder and endurance levels of normal children, between the ages of seven and ten years(2010-10-26) Benjamin, Natalie AliceIn South Africa, the concept of Developmental Co-ordination Disorder (DCD) is relatively unfamiliar and not well understood. The exact epidemiology is unknown, but the Diagnostic and Statistical Manual of Mental Disorders (DSM IV, 2000) indicate that the value could be between five and ten percent of the American population. Many studies on DCD have been conducted and most highlight the immense difficulties these children experience with motor activities, both in sport and daily tasks. However, few studies specifically investigated endurance and the impact it has on the child’s ability to function normally without too much effort and fatigue due to the condition. The main aim of this study was to determine the difference in submaximal endurance levels between children diagnosed with DCD and normally developing children. Children between the ages of seven and ten years were included in the study. The Six Minute Walk Test (6MWT) was employed to determine the average distance covered by each of two groups that were selected to participate in the study and thus, the submaximal endurance levels of each group. The first group of participants consisted of children having a diagnosis of DCD (n=31) and the second comparative group consisted of normally developing children (n=17). The results were analysed and compared using the Student t-test. Anthropometric data of height, age, gender and weight as well as baseline data of breathing rate, heart rate and peak flow were taken. These were compared to normative data as determined by the growth charts of the Centre for Disease Control and Prevention (CDC) as well as previous research on the various topics. The average distance covered by the DCD group was 375.89 metres with a standard deviation of ±73.33 and the mean distance covered by the normal comparative group was 430.48 metres with a standard deviation of ±60.85. When the two groups were compared it produced a p-value of 0.0086 which was a statistically significant difference. The normally developing group covered on average 54.6 metres more distance than the group with co-ordination difficulties. In comparison to studies that determined normal age (Lammers et al, 2008) and height (Li et al, 2007) reference values, the children within the eight-year age band for the normally developing group fell within the determined values. The other age bands fell below average for both the DCD and normally developing groups. The finding of the current study is important as it highlights the discrepancy in the submaximal endurance levels of children with DCD when compared to normally developing children of the same age. This is important when considering that most of the activities of daily living are performed at submaximal endurance levels and it is particularly important to note that these are the activities that children with DCD find challenging. The 6MWT can be performed by children as young as four years of age, with explanation and encouragement. This is particularly helpful in the clinical setting, as other tests of physical fitness require more time, equipment and generally good co-ordination in the individual being tested. The 6MWT is easy to apply and requires few tools, making it a cost and time effective means of testing submaximal fitness in children. It is thus a useful measure to determine whether therapeutic intervention has impacted endurance for activities of daily living.Item Systolic chamber function in rats with exercise-induced compared to pathological cardiac dilation(2009-04-17T12:12:51Z) Anamourlis, Prodromos ChristopherABSTRACT In pathological left ventricular hypertrophy (LVH) with a normal intrinsic myocardial function, eccentric chamber remodelling (cardiac dilatation) can produce a right shift in systolic pressure-volume (P-V) relations (systolic chamber dysfunction). Whether comparable degrees of cardiac dilatation in physiological (exercise-induced eccentric left ventricular remodelling) and pathological LVH produce similar effects on chamber function has not been determined. Hence, the aim of my thesis was to determine the impact of cardiac dilatation on systolic chamber function in chronically exercised rats with comparable increases in cardiac diastolic volumes as those produced by two rat models of pathological dilatation. Methods: Two models of cardiac dilatation were used, namely: (1) a model of pathological cardiac hypertrophy and dilatation (induced by chronic β-adrenoreceptor agonist administration to either Sprague-Dawley or spontaneously hypertensive rats), and (2) a model of physiological cardiac hypertrophy and dilatation (induced in Sprague-Dawley rats by 4-5 months of voluntary running activity on exercise wheels). 33 Sprague-Dawley rats were placed on spontaneous running wheels for 4-5 months (Exer group) and 24 Sprague-Dawley sedentary control rats (Con group) were placed individually in normal rat cages. To induced pathological dilatation, the β-agonist, isoproterenol (ISO) was administered daily to Sprague-Dawley rats for 7 months (SD-ISO, n=10) and to spontaneously hypertensive rats (SHR) for 4-5 months (SHR+ISO, n=22). Saline was administered daily to controls (SD, n=10; SHR, n=21) and to normotensive Wistar Kyoto rats (WKY, n=17). In isolated, perfused heart preparations, left ventricular (LV) dilatation was determined from the diastolic pressure-volume (P-V) relation and the volume intercept of the diastolic P-V relation (LV V0). Systolic chamber function was assessed by comparing LV developed pressures at specific filling volumes. Intrinsic systolic myocardial function was determined from the slope of the LV systolic developed stress-strain relation (myocardial systolic elastance). Results: ISO adminstered to SD and to SHR rats produced cardiac dilatation [LV V0 (ml): SD 0.20±0.01, SD-ISO 0.27±0.02, p<0.005; SHR 0.21±0.01, SHR-ISO 0.30±0.01, p<0.001], systolic chamber dysfunction (decrease in left ventricular developed pressures at incremental filling volumes) but normal intrinsic systolic myocardial function. Habitual exercise resulted in a right shifted LV diastolic P-V relation and an increased LV V0 (Exer 0.22±0.01, Con 0.18±0.01, p<0.005). In exercised rats (Exer-dilated, n=10) with equivalent dilatation as SD-ISO and SHR-ISO (LV V0 within 95% CI of SD-ISO and SHR-ISO), despite comparable LV diastolic P-V relations and LV V0 values (0.28±0.01); both systolic chamber function and intrinsic systolic myocardial function were normal. Conclusions: These data provide evidence to indicate that as compared to pathological dilatation, a similar extent of exercise-induced dilatation does not produce the same adverse effects on systolic chamber function.Item A systematic review of exercises used in a workplace setting, for the management of lower back pain(2008-06-06T08:51:05Z) Van der Merwe, Petronella DorotheaABSTRACT Aim: The aim of this study was to determine the most effective exercise program for the management of occupational lower back pain. Background: Occupational lower back pain accounts for 25% of workdays lost. The annual occurrence of occupational related lower back pain among blue collar workers in South Africa has shown to be between 55,7% and 63,9%. Methodology: Primary studies were searched with the use of the Entrez-cross-database search tool. Methodologies were assessed and critiqued. Data which included exercise detail, outcome measures of lower back pain intensity, painful episodes, sick leave and physical measures with statistical p-values was then extracted. Results: Nine primary studies, which included 11 exercise groups, complied to the inclusion and exclusion criteria. These studies proved to be of high methodology quality with quality scoring 70% on the quality assessment checklist. Exercise regimes, which included stretching, strengthening, endurance exercises and the combination use of stretching, strengthening and endurance exercises were identified and grouped according to the corresponding outcome measures. No meta-analysis could be done as no similar exercises with similar outcome measures could be found. Discussion: The limitations in the nine selected studies methodological quality were the lack of blinding of the assessors and subjects, and in six of the nine studies the lack of adequate participation rate among the intervention subjects. The validation process is acknowledged as a weakness within this study. Stretching, dynamic strengthening and endurance exercises were not statistically significant. Isometric exercise was statistically significant for lower back pain relief when the control group (p<0,0001) was compared to the experimental group. Isometric exercise however had no significant effect on abdominal strength at 9 months follow up period. Functionalexercises were statistically significant when the exercise group was compared to the control group with lower back pain intensity relief (p<0,018), painful episodes (p<0,018), sick leave (p< 0,0044). Functional exercises also had a long-term statistically significant effect on back muscle strength. A meta analysis could not be done due to insufficient similar studies. Conclusion: Although the methodology quality of the nine primary studies showed to be of high quality the validation process was a weakness within this study. Functional strengthening exercises were the most effective type of exercise for the management of occupational lower back pain among blue-collar workers. Future similar randomized control trials on exercise as an intervention to occupational lower back pain are needed to conduct a meta analysis. A meta analysis will be able to provide more evidence to establish which exercise regime is most effective for the management of occupational lower back pain.Item The influence of the menstrual cycle on exercise performance and stable isotopic tracer measures of fat metabolism(2007-03-02T11:18:49Z) Oosthuyse, TanjaNatural secretions of oestrogen and progesterone vary according to menstrual phase in eumenorrhoeic women and have an affect on physiological systems that could consequentially influence exercise performance. In a series of menstrual phase comparative investigations (considering mainly the early follicular (EF), late follicular (LF) and mid-luteal (ML) phase), I aimed to elucidate the physiological relation of oestrogen and progesterone to fat metabolism and ventilation during endurance exercise and exercise performance. I measured plasma free fatty acid (FFA) kinetics during prolonged exercise from an intravenous infusion of K+[1-13C]palmitate in eumenorrhoeic women and found the change in palmitate rate of appearance and disappearance between menstrual phases to be related to the oestrogen/progesterone (E/P) ratio. Overall the results from this study suggest that oestrogen promotes increases in FFA availability during exercise, while progesterone mitigates this response. Therefore, a high oestrogen concentration and E/P ratio in the ML phase is required in order to produce a favourable FFA metabolic response for endurance events. In order to estimate plasma FFA oxidation rate using carbon-FFA tracers, the acetate correction factor which accounts for carbon-label retention in secondary metabolic pools, must be applied. When I derived the acetate correction factor by measuring fractional recovery of carbon-13 in expired CO2 from a constant infusion of Na+[1- 13C]acetate during submaximal exercise we found the acetate correction factor to be significantly lower in the ML than EF phase (average change from EF phase -1.8± 0.5%, p<0.05). Failure to account for the lower correction factor in the ML phase will result in a 6% underestimation of plasma FFA oxidation rate. Furthermore, since human serum albumin (HSA) routinely used as a carrier for parenteral delivery of FFA tracers has various disadvantages, I tested the feasibility of using 2-hydroxypropyl-b- cyclodextrin (HP-b-CD) as a possible alternative carrier. A comparison of expired CO2 enrichment following HSA-FFA (7.4±2.0 %o) and HP-b-CD-FFA (8.6±2.1%o) infusion during exercise showed that the HP-b-CD does not compromise natural in vivo behaviour of the FFA tracer (p=0.4). Progesterone-induced hyperventilation is occasionally reported during exercise in the luteal phase. I found that the change in ventilatory parameters (minute ventilation and respiratory rate) during exercise from EF to ML phase is related to both the oestrogen and progesterone concentration in the ML phase. However, the associated increase in respiratory rate throughout prolonged exercise in the ML versus EF phase did not increase metabolic demand and therefore could not be expected to exacerbate fatigue. When exercise performance was evaluated by means of a cycling time trial, I found a trend for best performance in the LF phase versus the EF phase (8 of 11 subjects improved by 5.2±2.9%, p=0.027), while no differences occurred between other menstrual phases. Metabolic and performance benefits of oestrogen may be concealed in the ML phase by the coincident increase in progesterone in this phase and thus a significant effect is often only evident with a high E/P ratio in the ML phase. The transient LF phase, characterised by the pre-ovulatory surge in oestrogen, reveals the maximum benefits of oestrogen on metabolism and performance during submaximal exercise.Item The effect of Pilates on patients’ chronic low back pain. A pilot study.(2006-11-10T11:50:38Z) MacIntyre, LeanneThe Pilates exercise method applies many of the principles of lumbar stabilisation that have been found to be effective in the treatment of chronic low back pain. Pilates has recently found its way into the physiotherapy setting, where it is being integrated into the rehabilitation of patients with low back pain. This study consisted of a randomised control trial using an intervention group that underwent a twelve-week Pilates programme, and control group that continued with standardised physiotherapy treatment as necessary. Baseline, three-week, and twelve-week scores for a Visual Analogue Scale for pain and the Roland Morris Disability Questionnaire were recorded and compared. The Pilates group showed significantly greater improvements in pain and functional disability mean scores when compared to the control group (p=0.059 and p=0.026 respectively). It therefore appears that Pilates can be recommended as an effective treatment modality for the reduction of pain and the improvement of functional disability for chronic low back pain sufferers.