Cardiovascular disease is known as one of the leading causes of mortality worldwide, where low income countries or developing countries have the highest prevalence of cardiovascular disease. One of the main reasons for this statistics is acculturation that leads to changes in behavioral lifestyle and malnutrition within these countries. Low body mass index was found to be an independent risk factor for cardiovascular disease in several studies. From literature it is found that body mass index is lower than the ideal body mass index and is associated with cardiovascular disease. According to Higashi (2003) a body mass index of 22.2 kg/m2 is associated with the lowest morbidity. If body mass index decreases to lower values than the ideal body mass index, a J–curve will be evident suggesting higher prevalence of cardiovascular disease associated with low body mass index. These findings imply that not only high body mass index but also a low body mass index may be a risk factor for cardiovascular disease, morbidity and mortality. Whether low body mass index is associated with cardiovascular risk in an African population remains unclear. Objective: The aim of this study was to investigate the possible associations of low body mass index with variables of cardiovascular function in Africans, with a low socio–economic status. Methodology: This prospective cohort study (N= 2 010) is part of the Prospective Urban and Rural Epidemiology study (PURE) conducted in the North–West Province of South Africa in 2005, where the health transition in urban and rural subjects was investigated within an apparently low socio–economic status group. Our crosssectional PURE sub–study included 496 African people from rural and urban settings, (men, N= 252 and women, N= 244) aged between 35–65 years and body mass index lower than 25 kg/m2. Subjects were sub–divided into two groups. The first group consisted of Africans with a low body mass index smaller or equal to 20 kg/m2 (men; N= 152, women; N= 94) whilst the second group consisted of Africans with a normal body mass index larger than 20 kg/m2 and smaller or equal to 25 kg/m2 (men; N= 100, women; N= 150). Systolic blood pressure and diastolic blood pressure measurements were obtained with the validated OMRON HEM–757 device. The pulse wave velocity was measured using the Complior SP device. Blood was drawn by a registered nurse from the antebrachial vein using a sterile winged infusion set and syringes. Analyses for cholesterol, high density lipoprotein, triglycerides, gamma–glutamyl transferase and high sensitive C–reactive protein were completed utilizing the Konelab 20i. Data analyses were performed using the Statistica 10 program. Statistical analyses were executed to determine significant differences between age, body mass index and lifestyle factors as well as cardiovascular related variables in the different groups. T–tests were used to determine significant differences between independent groups. ANCOVA tests were used to determine BMI group differences independent of age, smoking and alcohol consumption. Partial correlations, which were adjusted for age, smoking and alcohol consumption, determined associations between the BMI groups and cardiovascular variables. Results: Our results indicated significantly higher mean values for the African men, with low body mass index, for cardiovascular variables (Diastolic blood pressure, 88.0 ± standard deviation (SD) 13.4 mmHg; mean arterial pressure, 103.8 ± SD 14.4 mmHg and carotid–radial pulse wave velocity, 12.6 ± SD 2.47 m/s) compared to the normal body mass index group (Diastolic blood pressure, 84.2 ± SD 12.2 mmHg; mean arterial pressure, 100.0 ± SD 13.2 mmHg and carotid–radial pulse wave velocity, 11.6 ± SD 2.00 m/s). The African women with low body mass index had a significant difference for carotid–radial pulse wave velocity (11.3 ± SD 2.43 m/s) compared to the normal body mass index group (10.6 ± SD 2.10 m/s). In African men, after the variables were adjusted for age, smoking and alcohol consumption, we revealed that diastolic blood pressure (88.0 with confidence interval (CI) [86.0– 90.0] mmHg) and carotid–radial pulse wave velocity (12.5 with CI [12.1–12.9] m/s) remained significant higher in the low body mass index group. Additionally, carotidradial pulse wave velocity was negatively associated with body mass index in African men. In the low body mass index group, Pearson and partial correlations of r= – 0.204; p= 0.012 and r= –0.200; p= 0.020 were found respectively in carotid–radial pulse wave velocity. Furthermore, in our unadjusted scatter plot with body mass index versus pulse wave velocity this negative trend of increasing carotid–radial pulse wave velocity with decreasing body mass index was noticeable in both African men and women. Even when carotid–radial pulse wave velocity was adjusted for age, smoking, alcohol consumption, mean arterial pressure and heart rate, a J–curve between carotid–radial pulse wave velocity and body mass index was still evident. Conclusion: A detrimental effect of low body mass index is evident on cardiovascular function in Africans. If body mass index decreases from the optimum value of 22.2 kg/m2 to lower values, a J–curve is evident between body mass index and cardiovascular variables suggesting higher prevalence of cardiovascular disease associated with low body mass index. In our sub–study the carotid–radial pulse wave velocity increases significantly in African men with low body mass index, thus supporting the theory that stiffening of the arteries is evident in Africans with a low body mass index. Low body mass index may contribute to the high prevalence of cardiovascular disease mortality within developing countries and therefore, increase the risk for cardiovascular disease. / Thesis (M.Sc. (Physiology))--North-West University, Potchefstroom Campus, 2012.

Cardiovascular disease is known as one of the leading causes of mortality worldwide, where low income countries or developing countries have the highest prevalence of cardiovascular disease. One of the main reasons for this statistics is acculturation that leads to changes in behavioral lifestyle and malnutrition within these countries. Low body mass index was found to be an independent risk factor for cardiovascular disease in several studies. From literature it is found that body mass index is lower than the ideal body mass index and is associated with cardiovascular disease. According to Higashi (2003) a body mass index of 22.2 kg/m2 is associated with the lowest morbidity. If body mass index decreases to lower values than the ideal body mass index, a J–curve will be evident suggesting higher prevalence of cardiovascular disease associated with low body mass index. These findings imply that not only high body mass index but also a low body mass index may be a risk factor for cardiovascular disease, morbidity and mortality. Whether low body mass index is associated with cardiovascular risk in an African population remains unclear. Objective: The aim of this study was to investigate the possible associations of low body mass index with variables of cardiovascular function in Africans, with a low socio–economic status. Methodology: This prospective cohort study (N= 2 010) is part of the Prospective Urban and Rural Epidemiology study (PURE) conducted in the North–West Province of South Africa in 2005, where the health transition in urban and rural subjects was investigated within an apparently low socio–economic status group. Our crosssectional PURE sub–study included 496 African people from rural and urban settings, (men, N= 252 and women, N= 244) aged between 35–65 years and body mass index lower than 25 kg/m2. Subjects were sub–divided into two groups. The first group consisted of Africans with a low body mass index smaller or equal to 20 kg/m2 (men; N= 152, women; N= 94) whilst the second group consisted of Africans with a normal body mass index larger than 20 kg/m2 and smaller or equal to 25 kg/m2 (men; N= 100, women; N= 150). Systolic blood pressure and diastolic blood pressure measurements were obtained with the validated OMRON HEM–757 device. The pulse wave velocity was measured using the Complior SP device. Blood was drawn by a registered nurse from the antebrachial vein using a sterile winged infusion set and syringes. Analyses for cholesterol, high density lipoprotein, triglycerides, gamma–glutamyl transferase and high sensitive C–reactive protein were completed utilizing the Konelab 20i. Data analyses were performed using the Statistica 10 program. Statistical analyses were executed to determine significant differences between age, body mass index and lifestyle factors as well as cardiovascular related variables in the different groups. T–tests were used to determine significant differences between independent groups. ANCOVA tests were used to determine BMI group differences independent of age, smoking and alcohol consumption. Partial correlations, which were adjusted for age, smoking and alcohol consumption, determined associations between the BMI groups and cardiovascular variables. Results: Our results indicated significantly higher mean values for the African men, with low body mass index, for cardiovascular variables (Diastolic blood pressure, 88.0 ± standard deviation (SD) 13.4 mmHg; mean arterial pressure, 103.8 ± SD 14.4 mmHg and carotid–radial pulse wave velocity, 12.6 ± SD 2.47 m/s) compared to the normal body mass index group (Diastolic blood pressure, 84.2 ± SD 12.2 mmHg; mean arterial pressure, 100.0 ± SD 13.2 mmHg and carotid–radial pulse wave velocity, 11.6 ± SD 2.00 m/s). The African women with low body mass index had a significant difference for carotid–radial pulse wave velocity (11.3 ± SD 2.43 m/s) compared to the normal body mass index group (10.6 ± SD 2.10 m/s). In African men, after the variables were adjusted for age, smoking and alcohol consumption, we revealed that diastolic blood pressure (88.0 with confidence interval (CI) [86.0– 90.0] mmHg) and carotid–radial pulse wave velocity (12.5 with CI [12.1–12.9] m/s) remained significant higher in the low body mass index group. Additionally, carotidradial pulse wave velocity was negatively associated with body mass index in African men. In the low body mass index group, Pearson and partial correlations of r= – 0.204; p= 0.012 and r= –0.200; p= 0.020 were found respectively in carotid–radial pulse wave velocity. Furthermore, in our unadjusted scatter plot with body mass index versus pulse wave velocity this negative trend of increasing carotid–radial pulse wave velocity with decreasing body mass index was noticeable in both African men and women. Even when carotid–radial pulse wave velocity was adjusted for age, smoking, alcohol consumption, mean arterial pressure and heart rate, a J–curve between carotid–radial pulse wave velocity and body mass index was still evident. Conclusion: A detrimental effect of low body mass index is evident on cardiovascular function in Africans. If body mass index decreases from the optimum value of 22.2 kg/m2 to lower values, a J–curve is evident between body mass index and cardiovascular variables suggesting higher prevalence of cardiovascular disease associated with low body mass index. In our sub–study the carotid–radial pulse wave velocity increases significantly in African men with low body mass index, thus supporting the theory that stiffening of the arteries is evident in Africans with a low body mass index. Low body mass index may contribute to the high prevalence of cardiovascular disease mortality within developing countries and therefore, increase the risk for cardiovascular disease. / Thesis (M.Sc. (Physiology))--North-West University, Potchefstroom Campus, 2012.

Physical activity has several advantages for health. The first objective of this research was to determine the relationship between physical activity and selected physical and psychological health components. The physical components include: diabetes risk, obesity, cholesterol and cardiovascular disease. The psychological health components include stress and depression. Secondly, this research aimed to determine the relationship between physical activity and medical costs. Medical costs were divided into pharmaceutical, general practitioners and hospital claims. A total of 9 860 employees of the same financial institution in South Africa, between the ages 18 and 64 (x̄ = 35.3 ± 18.6 years), participated in the study and participation was voluntary. No differentiation was made between race groups. The assessment of selected health risk factors and physical activity was done by using the Health Risk Assessment (HRA) methodology developed by the company, Monitored Health Risk (MHM). Assessment included a physical activity, diabetes risk and cardiovascular risk questionnaire, BMI and random blood glucose measurements, as well as stress and depression scores. The amount of days absent from work in the past six months was also determined by the questionnaire. Participants was categorised in three groups – low, moderate and high physical activity participation. Medical expenditure data was obtained from Monitored Health Risk Management Pty (Ltd). Hospital, pharmaceutical and general practitioners (GP) claims included all costs occurring during a six month period. The majority of the study group showed low physical activity participation (78.27%). The results also showed that both men and women showed an increased risk for diabetes, and high physical activity levels have a practically and statistically significant effect on the reduction of diabetes risk. In this study all the physical activity groups of both males and females showed an increased average body mass index (BMI) and therefore are considered to be an increased risk according to the classification as stipulated by the study perimeters. The average means for cholesterol in all groups are categorised as low risk. No significant differences are seen between the female groups as well as between the different male groups. The men in the study group showed higher cardiovascular risk than women. There are no statistically significant differences between the women’s groups. However, regarding the male groups, the low physically active male group showed significant differences to the high physical active male group. Thus, in this study it appears that the men participating in high levels of physical activity show the lowest risk for cardiovascular disease and therefore appear to be influenced by physical activity. The majority of the study group is shown to be in the high stress category (55.48%). It seems that work issues (82%), financial problems (74%) and family problems (69%) contribute most to the population’s high stress levels and depression experience. The Physical activity index (PAI) in relation to stress only shows practical significance in moderate and high physical women. The PAI and stress-related index reports statistically (p≤0.05; 0.001) significant and practice significant difference within the population. There was also a statistically significant (p≤0.05) relation between stress and physical activity in relation to days absent. Although high levels of stress and low levels of physical activity are present in the population, the relation become statistically significant in relation with depression. The study group was divided into two groups when the medical cost was examined. One group consisted of those individuals who do not use chronic medication and the other group, those individuals that use chronic medication. The majority of the study group (chronic and nonchronic medication use), show low physical activity participation (average of 78.80%). The results show statistically and practically significant differences between the groups that do not use chronic medication and the groups that use chronic medication. The women that use chronic medication show an increase in pharmaceutical costs with an increase in physical activity. However, when investigating the GP cost of women who use chronic medication, there is only a small difference in GP cost in the different physical activity participation categories. The data shows that men have higher pharmaceutical costs than women in all the physical activity categories. The results also indicate that men who use chronic medication, participating in low levels of physical activity do show higher pharmacy and GP costs. Medical cost associated with hospitalisation of those men whose chronic medications show an average higher medical cost (R231.72 versus R672.71). The women who are on chronic medication show about two and a half times higher hospitalisation cost (R253.97 versus R650.82) and the men an almost four times higher cost (R189.34 versus R721.71). No practically significant difference was found between the groups. The women show an increased incidence of low physical activity participation (82.38%), whereas 68.80% of the men show low physical activity participation. Women who use chronic medication and participate in moderate physical activity show lower hospital costs. The women in this study group that use chronic medication and participate in high levels of physical activity show the highest hospital cost. The men’s profile indicates that medical cost due to hospital claims rise with the higher levels of physical activity. / Thesis (PhD (Human Movement Sciences))--North-West University, Potchefstroom Campus, 2013.

Physical activity has several advantages for health. The first objective of this research was to determine the relationship between physical activity and selected physical and psychological health components. The physical components include: diabetes risk, obesity, cholesterol and cardiovascular disease. The psychological health components include stress and depression. Secondly, this research aimed to determine the relationship between physical activity and medical costs. Medical costs were divided into pharmaceutical, general practitioners and hospital claims. A total of 9 860 employees of the same financial institution in South Africa, between the ages 18 and 64 (x̄ = 35.3 ± 18.6 years), participated in the study and participation was voluntary. No differentiation was made between race groups. The assessment of selected health risk factors and physical activity was done by using the Health Risk Assessment (HRA) methodology developed by the company, Monitored Health Risk (MHM). Assessment included a physical activity, diabetes risk and cardiovascular risk questionnaire, BMI and random blood glucose measurements, as well as stress and depression scores. The amount of days absent from work in the past six months was also determined by the questionnaire. Participants was categorised in three groups – low, moderate and high physical activity participation. Medical expenditure data was obtained from Monitored Health Risk Management Pty (Ltd). Hospital, pharmaceutical and general practitioners (GP) claims included all costs occurring during a six month period. The majority of the study group showed low physical activity participation (78.27%). The results also showed that both men and women showed an increased risk for diabetes, and high physical activity levels have a practically and statistically significant effect on the reduction of diabetes risk. In this study all the physical activity groups of both males and females showed an increased average body mass index (BMI) and therefore are considered to be an increased risk according to the classification as stipulated by the study perimeters. The average means for cholesterol in all groups are categorised as low risk. No significant differences are seen between the female groups as well as between the different male groups. The men in the study group showed higher cardiovascular risk than women. There are no statistically significant differences between the women’s groups. However, regarding the male groups, the low physically active male group showed significant differences to the high physical active male group. Thus, in this study it appears that the men participating in high levels of physical activity show the lowest risk for cardiovascular disease and therefore appear to be influenced by physical activity. The majority of the study group is shown to be in the high stress category (55.48%). It seems that work issues (82%), financial problems (74%) and family problems (69%) contribute most to the population’s high stress levels and depression experience. The Physical activity index (PAI) in relation to stress only shows practical significance in moderate and high physical women. The PAI and stress-related index reports statistically (p≤0.05; 0.001) significant and practice significant difference within the population. There was also a statistically significant (p≤0.05) relation between stress and physical activity in relation to days absent. Although high levels of stress and low levels of physical activity are present in the population, the relation become statistically significant in relation with depression. The study group was divided into two groups when the medical cost was examined. One group consisted of those individuals who do not use chronic medication and the other group, those individuals that use chronic medication. The majority of the study group (chronic and nonchronic medication use), show low physical activity participation (average of 78.80%). The results show statistically and practically significant differences between the groups that do not use chronic medication and the groups that use chronic medication. The women that use chronic medication show an increase in pharmaceutical costs with an increase in physical activity. However, when investigating the GP cost of women who use chronic medication, there is only a small difference in GP cost in the different physical activity participation categories. The data shows that men have higher pharmaceutical costs than women in all the physical activity categories. The results also indicate that men who use chronic medication, participating in low levels of physical activity do show higher pharmacy and GP costs. Medical cost associated with hospitalisation of those men whose chronic medications show an average higher medical cost (R231.72 versus R672.71). The women who are on chronic medication show about two and a half times higher hospitalisation cost (R253.97 versus R650.82) and the men an almost four times higher cost (R189.34 versus R721.71). No practically significant difference was found between the groups. The women show an increased incidence of low physical activity participation (82.38%), whereas 68.80% of the men show low physical activity participation. Women who use chronic medication and participate in moderate physical activity show lower hospital costs. The women in this study group that use chronic medication and participate in high levels of physical activity show the highest hospital cost. The men’s profile indicates that medical cost due to hospital claims rise with the higher levels of physical activity. / Thesis (PhD (Human Movement Sciences))--North-West University, Potchefstroom Campus, 2013.