Motivation: Cardiovascular disease (CVD) is one of the leading causes of mortality and morbidity in South Africa and worldwide. Various investigations have confirmed the hypothesis that elevated plasma homocysteine (Hcy) levels may be linked to vascular disease, and it has become clear that hyperhomocysteinemia is an independent risk factor for atherosclerosis and atherothrombosis. Extensive research on the influence of vitamin supplementation leading to the lowering of homocysteine levels has been done, but extensive research on the effect of physical activity on high homocysteine levels is lacking. The interaction of vitamin supplementation in combination with physical activity has also not been investigated. If a conditioning exercise programme can demonstrate a lowering effect on elevated homocysteine levels, it will confirm the importance of physical activity as a less expensive alternative for a better lifestyle that can also continue to lower morbidity and mortality rates. Objective: This study examined the effect of a conditioning program, vitamin supplement and a combination of both on Hcy levels in men with coronary heart disease risk factors. Methods: In a randomized, placebo-controlled, blinded crossover study, 84 men matched for physical activity (PA) levels, age and risk factors were randomly assigned to one of 4 groups [A = physical conditioning, 20-30 min; 70-80% (THR), 8 = physical conditioning + supplement, C = supplement (12,5 ug vitamin 812; 200 ug folic acid) or D = control). Groups A, B, and C were crossed over according to the Latin square design. Total plasma homocysteine, maximal oxygen consumption (V02max) and body composition (BMI & Fat %) were measured before and after each 12-week intervention period. A 6-week washout period separated the crossovers. Results: The experimental and control groups presented similar baseline characteristics and the profile analysis of the V02max values and Hcy concentrations indicated positive results (multivariate p-value <0.0001), due to the fact that the four groups repeated measurements, presented different patterns. A phase effect for the V02max values and a phase and interaction effect for the Hcy concentrations were indicated, though all the subjects were requested to maintain their normal daily routine (eating pattern, PA levels and alcohol consumption) for the duration of the study. The lack of compliance to the conditioning programme makes it impossible to draw conclusions for V02max values. The poor compliance lead to a small sample size that eventually leads to less statistical power. Conclusion: This study found that a 12-week conditioning programme had no effect on Hcy concentrations. The results of this study make it impossible, due to poor compliance, to suggest that the effect of increased PA on homocysteine may play an important role in the prevention and treatment of CVD. It is, therefore, recommended that more studies should be conducted to further investigate the effect of PA and vitamin supplements on tHcy levels. / Thesis (M.Sc. (Human Movement Science))--North-West University, Potchefstroom Campus, 2006.

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Motivation: Cardiovascular disease (CVD) is one of the leading causes of mortality and morbidity in South Africa and worldwide. Various investigations have confirmed the hypothesis that elevated plasma homocysteine (Hcy) levels may be linked to vascular disease, and it has become clear that hyperhomocysteinemia is an independent risk factor for atherosclerosis and atherothrombosis. Extensive research on the influence of vitamin supplementation leading to the lowering of homocysteine levels has been done, but extensive research on the effect of physical activity on high homocysteine levels is lacking. The interaction of vitamin supplementation in combination with physical activity has also not been investigated. If a conditioning exercise programme can demonstrate a lowering effect on elevated homocysteine levels, it will confirm the importance of physical activity as a less expensive alternative for a better lifestyle that can also continue to lower morbidity and mortality rates. Objective: This study examined the effect of a conditioning program, vitamin supplement and a combination of both on Hcy levels in men with coronary heart disease risk factors. Methods: In a randomized, placebo-controlled, blinded crossover study, 84 men matched for physical activity (PA) levels, age and risk factors were randomly assigned to one of 4 groups [A = physical conditioning, 20-30 min; 70-80% (THR), 8 = physical conditioning + supplement, C = supplement (12,5 ug vitamin 812; 200 ug folic acid) or D = control). Groups A, B, and C were crossed over according to the Latin square design. Total plasma homocysteine, maximal oxygen consumption (V02max) and body composition (BMI & Fat %) were measured before and after each 12-week intervention period. A 6-week washout period separated the crossovers. Results: The experimental and control groups presented similar baseline characteristics and the profile analysis of the V02max values and Hcy concentrations indicated positive results (multivariate p-value <0.0001), due to the fact that the four groups repeated measurements, presented different patterns. A phase effect for the V02max values and a phase and interaction effect for the Hcy concentrations were indicated, though all the subjects were requested to maintain their normal daily routine (eating pattern, PA levels and alcohol consumption) for the duration of the study. The lack of compliance to the conditioning programme makes it impossible to draw conclusions for V02max values. The poor compliance lead to a small sample size that eventually leads to less statistical power. Conclusion: This study found that a 12-week conditioning programme had no effect on Hcy concentrations. The results of this study make it impossible, due to poor compliance, to suggest that the effect of increased PA on homocysteine may play an important role in the prevention and treatment of CVD. It is, therefore, recommended that more studies should be conducted to further investigate the effect of PA and vitamin supplements on tHcy levels. / Thesis (M.Sc. (Human Movement Science))--North-West University, Potchefstroom Campus, 2006.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal