<p> This study examined the effects of isometric handgrip training (IHG) on resting blood pressure and resting arterial compliance in the carotid and brachial arteries of medicated hypertensive individuals. Previous studies found that isometric training reduced resting arterial blood pressure (RBP) in high-normal and medicated hypertensive individuals. Investigators have also found an improvement in central arterial compliance with aerobic training and a reduction in central arterial compliance with age, cardiovascular disease and resistance training. The effects of isometric training on arterial compliance have not been examined previously.</p> <p> Ten participants participated in a one-hand IHG intervention, nine participants in a two-hand IHG intervention and 5 participants served as the non-exercising controls. Each experimental group performed four, 30% maximal voluntary IHG contractions for 2 minutes, 3 days a week, for 8 weeks. The one-hand group trained only their non-dominant hand, while the two-hand group trained both hands. Measurements of resting arterial blood pressure, and cross sectional compliance of the brachial and carotid arteries were made pre-training, after four weeks of training and after the completion of the eight-week training protocol.</p> <p> There were no changes in resting arterial blood pressure after training. Mean carotid and brachial artery diameters did not change with resistance training. There were no significant changes in brachial or carotid cross sectional compliance with isometric training. In conclusion, moderated level isometric training did not elicit changes in resting arterial blood pressure and resting muscular and elastic arterial compliance in medicated hypertensive individuals compared to a non-exercising control group.</p> / Thesis / Master of Science (MSc)

Cardiovascular diseases (CVDs) remain the leading cause of death worldwide. Patients at risk of evolving CVDs are assessed by evaluating a risk factor-based score that incorporates different bio-markers ranging from age and sex to arterial stiffness (AS). AS depicts the rigidity of the arterial vessels and leads to an increase in the arterial pulse pressure, affecting the heart and vascular physiology. These facts have encouraged researchers to propose surrogate markers of cardiovascular risks and develop simple and non-invasive models to better understand cardiovascular system operations. This work thus fundamentally capitalizes on developing a novel class of low-dimensional physics-based fractional-order models of systemic arteries and exploring the feasibility of fractional differentiation order to portray the vascular stiffness. Fractional-order modeling is a successful paradigm to integrate multiscale and interconnected mechanisms of the complex arterial system. However, this type of modeling alone often fails to efficiently integrate altered variabilities in vascular physiology from various sources of large datasets, multi-modalities, and levels. In this regard, combining fractional-order-based approaches with machine learning techniques presents a unique opportunity to develop a powerful prediction framework that reveals the correlation between intertwined vascular events. This work is divided into three parts. The first part contributes to developing the fractional-order lumped parametric model of the arterial system. First, we propose fractional-order representations to model and characterize the complex and frequency-dependent apparent arterial compliance. Second, we propose fractional-order arterial Windkessel modeling the aortic input impedance and hemodynamic. Subsequently, the proposed models have been applied and validated using both human in-silico healthy datasets and real vascular aging and hypertension. The second part addresses the non-zero initial value problem for fractional differential equations (FDEs) and proposes an estimation technique for joint estimation of the input, parameters, and fractional differentiation order of non-commensurate FDEs. The performance of the proposed estimation techniques is illustrated on arterial and neurovascular hemodynamic response models. The third part explores the feasibility of using machine learning algorithms to estimate the gold-standard measurement of AS, carotid-to-femoral pulse wave velocity. Different modalities have been investigated to generate informative input features and reduce the dimensionality of the time series pulse waves.

<p> Increased arterial stiffness and vascular endothelial dysfunction have been identified as independent risk factors for the development and progression of cardiovascular disease. Traditional endurance training has been associated with elevated levels of central arterial compliance and an attenuation of cardiovascular events. As well, the positive benefits of aerobic-based training have been acknowledged as effective modulators of vascular endothelial function. To date, the impact of sprint interval training on cardiovascular health has not been evaluated. Furthermore, the mechanisms responsible for previously observed enhancements in endurance (750 kJ) performance following two weeks of sprint interval training remain unclear, but may be related to changes in vascular structure and function.</p> <p> Nine young healthy males [age: 22 ± 0.5 (mean± SEM)] participated in a two week sprint interval training program consisting of 4-6 30 second maximum effort exercise bouts performed every other day on a cycle ergometer. In addition, each participant was required to complete a 750 kJ time trial on a cycle ergometer as a measure of aerobic exercise performance before (PRE) and after (POST) training. Measurements of supine, resting carotid pulse pressure, carotid cross-sectional compliance, and brachial vascular endothelial function (using flow mediated dilation) were also acquired PRE and POST training.</p> <p> Resting pulse pressure did not show any significant changes with exercise training (PRE= 48.6±1.6, POST= 52.4±2.5 mmHg, p>0.05). Mean brachial artery diameter was not changed with sprint interval training (PRE= 4.29±0.17, POST= 4.38±0.18 mm, p>0.05); however, mean carotid artery diameter increased significantly PRE to POST (PRE= 6.40±0.15, POST= 6.49±0.14 mm, p=0.008). Carotid cross-sectional compliance did not change PRE to POST training (PRE= 0.164±0.010, POST= 0.162±0.007 mm^2/mmHg, p>0.05). Brachial vascular endothelial function measured using flow-mediated dilation did not show a significant change with sprint interval training, however a trend towards improvement was noted (PRE= 4.6±1.8, POST= 6.4±1.0 %, p=0.296). When normalized for shear rate (which was also unaltered with sprint interval training) there were no changes in endothelial function (PRE = 0.158±0.068, POST= 0.198 ± 0.034 %/S^-1, p>0.05). Average brachial post-occlusion blood flow was significantly enhanced following training possibly revealing enhanced resistance vessel function (PRE= 296.0±37.4, POST= 324.8±38.8 ml/min, p=0.04), despite no change in peak brachial blood flow (PRE= 332.0±42.3, POST= 362.6±45.7 ml/min, p>0.05). 750 kJ time trial performance was significantly enhanced with training (PRE = 62.8±4.9; POST= 55.84±3.55 min; p=0.006).</p> <p> In conclusion, sprint interval training did not change resting carotid compliance or brachial endothelial function, despite significant improvements in aerobic performance (750 kJ). However, carotid resting diameters and brachial post occlusion blood flow were significantly increased PRE to POST and a trend towards improvement was seen for brachial flow mediated dilation. The exact mechanisms responsible for such changes remain unknown and require further investigation.</p> / Thesis / Master of Science (MSc)

Background: In the past 37 years, increased efforts have been directed toward a better understanding of the importance of Hcy in disease and it has now become clear that hyperhomocysteinemia is a major independent risk factor for CVD. Extensive research on the influence of vitamin supplementation leading to reductions in Hcy levels and improvements in cardiovascular function has been done. The importance of exercise in the lowering of cardiovascular risk factors, as well as its favourable influence on cardiovascular function has also been indicated in several studies, however, the limited number of studies investigating the effect of exercise on Hcy concentrations revealed contradicting results. Furthermore, a relationship between Hcy concentration and cardiovascular function with the intervention of an exercise training and a vitamin supplementation programme respectively has also not been investigated. Objective: The objective of this study was to examine the effect of a 12-week exercise training and a 12-week vitamin supplementation intervention respectively on tHcy concentrations and cardiovascular function, and whether the change in tHcy concentration within the different interventions correlated with the change in cardiovascular function. Methods: In a randomised controlled cross-over intervention study, 52 men matched for age, cardiorespiratory fitness levels and cardiovascular risk factors were randomly assigned to one of 3 groups (Group A = exercise training programme, 20-30min. at 70-80% of HRmax; Group B = 400 g folic acid and 25 g vitamin B12 supplement; Group C = control). Group A and B were crossed over for phase 11, and Group C remained the control. The questionnaires were completed, and the body composition variables (BMI, WHR and body fat percentage), cardiovascular function (Finometer), tHcy concentrations and VO2max, were measured before and after each 12-week intervention period. A 6-week washout period separated the crossovers. Results: The ANCOVA, adjusted for age and BMI, showed that the percentage change from baseline to end, corrected for baseline of the tHcy concentration increased significantly (p ≤ .05) by 9.7% with the exercise training intervention and decreased significantly (p ≤ .05) by 12.9%, with the vitamin supplementation intervention. The ANCOVA of the percentage change from baseline to end in cardiovascular function showed that the vitamin supplementation intervention resulted in improvements in cardiovascular function (decreased resting MAP, TPR and increased resting SV, CO, Cw) in comparison to the impairment in cardiovascular function with the exercise training intervention (increased resting DBP, MAP and TPR). The relationship between the tHcy concentration and cardiovascular function at baseline and within each of the different interventions were assessed by partial correlations adjusted for age, BMI and VO2max. Significant (p ≤ .05) relationships only occurred within the vitamin supplementation intervention, where decreased percentage change in tHcy concentration significantly correlated with increased percentage change of resting SV and CO and decreased percentage change of resting TPR. Conclusion: The general conclusion that can be drawn is that a 12-week vitamin supplementation intervention showed increased health related results, e.g. a significant reduction in tHcy concentration, an improvement in cardiovascular function and a significant positive relationship between these b o factors, in comparison to the 12-week exercise training intervention that significantly increased the tHcy concentration and did not show increased health related results. Due to inadequate compliance to the exercise training intervention, no conclusion can be drawn with regard to the effect of exercise training on tHcy concentrations and cardiovascular function. / Thesis (M.Sc. (Human Movement Science))--North-West University, Potchefstroom Campus, 2007

Thesis (M.Sc. (Human Movement Science))--North-West University, Potchefstroom Campus, 2007.

Background: In the past 37 years, increased efforts have been directed toward a better understanding of the importance of Hcy in disease and it has now become clear that hyperhomocysteinemia is a major independent risk factor for CVD. Extensive research on the influence of vitamin supplementation leading to reductions in Hcy levels and improvements in cardiovascular function has been done. The importance of exercise in the lowering of cardiovascular risk factors, as well as its favourable influence on cardiovascular function has also been indicated in several studies, however, the limited number of studies investigating the effect of exercise on Hcy concentrations revealed contradicting results. Furthermore, a relationship between Hcy concentration and cardiovascular function with the intervention of an exercise training and a vitamin supplementation programme respectively has also not been investigated. Objective: The objective of this study was to examine the effect of a 12-week exercise training and a 12-week vitamin supplementation intervention respectively on tHcy concentrations and cardiovascular function, and whether the change in tHcy concentration within the different interventions correlated with the change in cardiovascular function. Methods: In a randomised controlled cross-over intervention study, 52 men matched for age, cardiorespiratory fitness levels and cardiovascular risk factors were randomly assigned to one of 3 groups (Group A = exercise training programme, 20-30min. at 70-80% of HRmax; Group B = 400 g folic acid and 25 g vitamin B12 supplement; Group C = control). Group A and B were crossed over for phase 11, and Group C remained the control. The questionnaires were completed, and the body composition variables (BMI, WHR and body fat percentage), cardiovascular function (Finometer), tHcy concentrations and VO2max, were measured before and after each 12-week intervention period. A 6-week washout period separated the crossovers. Results: The ANCOVA, adjusted for age and BMI, showed that the percentage change from baseline to end, corrected for baseline of the tHcy concentration increased significantly (p ≤ .05) by 9.7% with the exercise training intervention and decreased significantly (p ≤ .05) by 12.9%, with the vitamin supplementation intervention. The ANCOVA of the percentage change from baseline to end in cardiovascular function showed that the vitamin supplementation intervention resulted in improvements in cardiovascular function (decreased resting MAP, TPR and increased resting SV, CO, Cw) in comparison to the impairment in cardiovascular function with the exercise training intervention (increased resting DBP, MAP and TPR). The relationship between the tHcy concentration and cardiovascular function at baseline and within each of the different interventions were assessed by partial correlations adjusted for age, BMI and VO2max. Significant (p ≤ .05) relationships only occurred within the vitamin supplementation intervention, where decreased percentage change in tHcy concentration significantly correlated with increased percentage change of resting SV and CO and decreased percentage change of resting TPR. Conclusion: The general conclusion that can be drawn is that a 12-week vitamin supplementation intervention showed increased health related results, e.g. a significant reduction in tHcy concentration, an improvement in cardiovascular function and a significant positive relationship between these b o factors, in comparison to the 12-week exercise training intervention that significantly increased the tHcy concentration and did not show increased health related results. Due to inadequate compliance to the exercise training intervention, no conclusion can be drawn with regard to the effect of exercise training on tHcy concentrations and cardiovascular function. / Thesis (M.Sc. (Human Movement Science))--North-West University, Potchefstroom Campus, 2007

Until recently, tests of vascular structure, function and compliance have been used predominantly for assessing the efficacy of treatment – for example, aggressive medical therapy may yield improvements in vascular structure and function with a concomitant decrease in cardiac events. However, the role of abnormal vessel function in the development of atherosclerosis, and the relationship of structural changes in peripheral vessels with coronary disease might suggest that these tests could be used as a screening test for patients with subclinical coronary disease. At present, there is insufficient evidence to support the theory that normal vascular structure and function can rule out significant coronary disease, and indeed, such an association may be confounded by the presence of risk factors that alter these test results in the absence of significant coronary artery disease (CAD). The overall hypothesis of the studies undertaken in this thesis was that utilizing contemporary technology during ultrasonic and tonometric assessment of arterial structure, function and compliance, it is possible to non-invasively characterise both early and advanced arterial dysfunction and identify patients both at risk and with cardiovascular disease. The aim of these studies was to determine whether these tests can be used to guide intervention when arterial dysfunction is diagnosed and whether they are robust enough as a follow-up tool. The thesis initially reviews arterial structure, function and compliance and their relationship to cardiovascular risk and in particular, CAD. This review provides a rationale for the studies undertaken here to resolve clinical and technical issues as well as provide an insight into the tests chosen to assess arterial function. The second chapter discusses the methodology used in these studies to assess arterial structure, function and compliance, diagnose coronary artery disease and determine cardiovascular risk. They range from stress echocardiography for the diagnosis of CAD to tests for arterial structure (carotid intima-media thickness [IMT]), endothelial function (brachial artery reactivity [BAR]), local arterial distensibility (distensibility coefficient [DC]) and systemic or total arterial compliance (TAC). In addition, several methods will be discussed for assessing local arterial elasticity with a novel imaging technique. The rationale for using tests for arterial structure, function and compliance in patients with CAD as well as cardiovascular risk is examined in chapter 3. Chapter 3 examines the use of TAC, IMT and BAR in patients undergoing dobutamine stress echocardiography (DSE) in a group of patients with and without disease. TAC was neither an independent predictor of CAD risk or patients having CAD in this study. BAR was a predictor of risk status but not of patients having CAD. Only IMT was an independent predictor of both patients at risk for CAD and those with CAD. In chapter 3 both pulse pressure and total arterial compliance were only univariate predictors of risk for CAD. Chapter 4 examines three different methods of estimating TAC, all based on the two-element Windkessel model in 320 patients with and without cardiovascular risk. The pulse-pressure method (PPM) is based on a combination of pressure, obtained using applanation tonometry of the radial artery, and an estimate of stroke volume obtained by Doppler echocardiography of the left ventricular outflow and by 2D echocardiographic dimension of the left ventricular outflow tract. The area method (AM) is an integral variation of the Windkessel equations and is based on the derived central pressure waveform. The stroke volume-pulse pressure method (SVPP) is a simple ratio of stoke volume and pulse pressure. We conclude that they correlate well and show similar differences between groups with and without risk. The PPM had the smallest difference from the mean and standard deviation in Bland Altman analysis and we therefore used the PPM for most future studies. Chapter 5 discusses the use of tissue Doppler for the derivation of central pressure and determination of distensibility coefficient, a marker of local arterial elasticity. Tissue Doppler can be used to evaluate the low frequency, high amplitude signals which come from tissue by changing filtering settings on an ultrasound machine. Using off-line software, the tissue velocities can be extracted and with a processing algorithm, vessel wall displacement values over time can be generated. These vessel wall displacement values which are in microns (µm) can then be used to calculated distensibility coefficient which is calculated as 2*((net displacement/minD)/PP). We studied a large group of patients with and without cardiovascular risk and conclude that DC using tissue Doppler correlates highly with DC by B-mode and M-mode imaging and is also very reproducible. In a subgroup, the vessel displacement values were “calibrated” using mean and diastolic pressure and with specialised software and a transfer function, central pressure wave forms were reconstructed. In this study we conclude that the central pressure obtained using tissue Doppler displacement of the carotid artery correlates highly with that obtained using applanation tonometry although there are technical challenges involved. With the known prognostic value of pulse pressure, chapter 6 explores whether there is added benefit to measuring total arterial compliance over pulse pressure alone. Once again patients with and without disease were studied and we conclude that brachial pulse pressure correlates well with TAC in men with normal cardiac function. However, in women and in patients at the low and high extremes of function, and in patients with preclinical and overt cardiovascular disease, there appears to be incremental value in measuring TAC. The role of cardiovascular risk factors in association with TAC is examined in chapter 7. Several studies have shown that TAC is lower in certain groups due to age, height, hypertension, hyperlipidaemia or other factors. We studied 720 patients with and without cardiovascular risk factors and did several multiple linear regression models based on anthropomorphic variables. Age was an independent correlate of TAC in most of the regression models and we conclude that TAC is associated with multiple risk factors, but age is a major determinant. The influence of age and other correlates may dwarf the contribution of individual risk factors and therefore their alteration with therapy. Chapter 8 examines the correlates of preclinical cardiovascular disease in both indigenous and non-indigenous Australians with and without diabetes mellitus (DM). DM is a major health problem in the Indigenous population in Australia and CVD occurs earlier in this group than in caucasians and is responsible for 1/3 of all deaths. We studied a large group of indigenous Australians with and without DM and matched them to a caucasian population. There were no differences in BAR between the groups probably due to large standard deviations in the measurements. In assessing DC, both DM groups had significantly lower DC than the non-DM groups. However, in the IMT analysis both of the indigenous groups had significantly higher IMT than their caucasian counterparts and even after IMT was corrected for age, Indigenous patients even at an early age had significantly higher IMT. We conclude that despite a high incidence of risk factors in indigenous Australians both with and without DM, ethnicity (and various other risk factors for which it is a marker) appears to be an independent predictor of preclinical cardiovascular disease. In chapter 3 we determined that TAC was not an independent correlate of patients either at risk of CAD or with CAD. Chapter 9 discusses the results of a study of patients presenting for stress echocardiography for either detection of CAD or risk stratification. Ischaemia was detected in 25% of cases and TAC was similar in those with and without ischaemia. In multiple linear regression models however, in addition to cardiovascular risk factors TAC was independently associated with both the presence of CAD and the extent of ischaemia at stress echocardiography. Several studies have used vascular function as an outcome measure in intervention trials, either lifestyle or pharmacologic. In chapter 10 we undertook a lifestyle and diet intervention study in a large group of healthy patients with type-II DM. The tests for IMT, BAR and TAC were used in addition to biochemical markers and fitness assessment. At follow-up the intervention group had significant changes in weight and BMI and significantly increased fitness but failed to show any changes in any of the vascular parameters. We conclude that while metabolic and fitness parameters respond to treatment in patients with type-II DM, the early changes seen in vascular structure, function and compliance may not change in the long term. Although TAC has been correlated with hypertension, LVH, myocardial ischaemia and heart failure there are few data existing regarding the relationship of TAC to outcome. In the final chapter of this thesis we sought whether TAC was predictive of outcome in a large, primary prevention group of patients with varying degrees of cardiovascular risk. We followed up 719 patients who were studied between 2001 and 2008 in Brisbane, Australia and examined TAC in relation to mortality and a composite endpoint of death or hospital admission. There were significant differences in groups having low and normal TAC for both death and the composite endpoint and in patients with intermediate and high Framingham 10-year risk TAC was an independent predictor of both death and the composite endpoint. We conclude that TAC correlates with outcome in patients with varying degrees of cardiovascular risk and also adds incremental benefit to Framingham risk alone in patients with intermediate risk.

This study was aimed at determining whether the digital volume pulse waveform using the Pulse Sensor can be used to extract features related to arterial compliance. The Pulse Sensor, a low-cost photoplethysmograph, measures green light reflection in the finger and generates output, which is indicative of blood flow and can be read by the low-cost Arduino UNO™. The Pulse Sensor code was modified to increase the sampling frequency and to capture the data in a file, which is subsequently used for waveform analysis using programs written in the R system. Waveforms were obtained using the Pulse Sensor during two 30-s periods of seated rest, in each of 44 participants, who were between the ages of 20 and 80 years. For each cardiac cycle, the first four derivatives of the waveform were calculated and low-pass filtered by convolution before every differentiation step. The program was written to extract 19 features from the pulse waveform and its derivatives. These features were selected from those that have been reported to relate to the physiopathology of hemodynamics. Results indicate that subtle features of the pulse waveform can be calculated from the fourth derivative. Feature misidentification occurred in cases of saturation or low voltage and resulted in outliers; therefore, trimmed means of the features were calculated by automatically discarding the outliers. There was a high efficiency of extraction for most features. Significant relationships were found between several of the features and age, and systolic, diastolic, and mean arterial blood pressure, suggesting that these features might be employed to predict arterial compliance. Further improvements in experimental design could lead to a more detailed evaluation of the Pulse Sensor with respect to its capability to predict factors related to arterial compliance.

Several research studies indicate the increasing problem obesity has become over the past few decades (Andersen 1999:41; Fox, 1999:56-60; Kuczmarshi et al., 1994:205-212). Obesity, after cigarette smoke, is the leading cause of death in the USA and a combination of diet factors and physical inactivity (two primary contributors of obesity) leads to an average of 300,000 deaths per year (McGinnis & Foege, 1993:2207-2212). Previously little information was available on the effect of obesity on the peripheral vascularization, and even less about the effect of obesity on arterial compliance (Raison et al., 1998:299-303). Research indicated a decrease in arterial compliance with an increase in body weight (Kumaran et al., 2002:7; Sutton-Tyrrell et al., 2001:431; Tounian et al., 2001:1400-1404; Stepniakowski & Egan, 1995:R567) however, contradictory research where no association between obesity and arterial compliance was indicated, has also been found (Singhal et al., 2002:1920; Mangoni et al., 1995:986). Mackey et al. (2002:16) also found that an increased aortic stiffness is positively associated with lowered physical activity levels. A lifestyle consisting of moderate physical activity, has a positive effect on the health, lowering of chronic illness risks, the prevention of cardiovascular diseases and the improvement of quality of lie in overweight and obese patients (Adams et al., 2003542; Ferreira et al., 2003:1670-1678; Macera, 2003:123; Mclnnis, 200396; Kolden et al., 2002:447). Moderate aerobic exercise is also seen as a potential non-pharmaceutical therapeutic method to increase age associated decrease in arterial compliance in young, middle aged and older adults (Gates et al., 2003:2213; Havlik et al., 2003:156; Seals, 2003:68; Moreau et al., 2003:865; Joyner, 2000:1214; Cameron et al., 1999:653). The objective of this study was firstly to determine the correlation between obesity and vascular function in Caucasian women between the ages 19 and 56 and to determine which marker of obesity is the best predictor of a weakened vascular function (see article one). The second objective was to determine the correlation between physical activity, obesity and arterial compliance in Caucasian women between the ages 19 and 56 years (see article 2). A total of 115 Caucasian women were recruited to participate in this study. Anthropometric measurements and a comprehensive body composition profile was taken using the BOD POD. The Finometer apparatus was used to measure the arterial compliance and the sphygmomanometer to measure the subjects blood pressure. The subjects completed the Yale Physical Activity Survey questionnaire to determine their physical activity index. This study seems to indicate a positive relationship between arterial compliance and obesity which could be explained by the influence blood volume had in determining arterial compliance. A negative correlation was found between obesity and blood pressure where an increase in obesity caused an increase in both systolic and diastolic blood pressure. A positive correlation was found between physical activity and obesity. The higher the activity levels were in this study, the less obese the subjects tended to be. No correlation was found between physical activity and arterial compliance. A clear trend, even though no statistically significant differences, was found between physical activity and blood pressure. The more active the subjects were, the lower their blood pressure tended to be. / Thesis (M.Sc. (Human Movement Science))--North-West University, Potchefstroom Campus, 2005

Several research studies indicate the increasing problem obesity has become over the past few decades (Andersen 1999:41; Fox, 1999:56-60; Kuczmarshi et al., 1994:205-212). Obesity, after cigarette smoke, is the leading cause of death in the USA and a combination of diet factors and physical inactivity (two primary contributors of obesity) leads to an average of 300,000 deaths per year (McGinnis & Foege, 1993:2207-2212). Previously little information was available on the effect of obesity on the peripheral vascularization, and even less about the effect of obesity on arterial compliance (Raison et al., 1998:299-303). Research indicated a decrease in arterial compliance with an increase in body weight (Kumaran et al., 2002:7; Sutton-Tyrrell et al., 2001:431; Tounian et al., 2001:1400-1404; Stepniakowski & Egan, 1995:R567) however, contradictory research where no association between obesity and arterial compliance was indicated, has also been found (Singhal et al., 2002:1920; Mangoni et al., 1995:986). Mackey et al. (2002:16) also found that an increased aortic stiffness is positively associated with lowered physical activity levels. A lifestyle consisting of moderate physical activity, has a positive effect on the health, lowering of chronic illness risks, the prevention of cardiovascular diseases and the improvement of quality of lie in overweight and obese patients (Adams et al., 2003542; Ferreira et al., 2003:1670-1678; Macera, 2003:123; Mclnnis, 200396; Kolden et al., 2002:447). Moderate aerobic exercise is also seen as a potential non-pharmaceutical therapeutic method to increase age associated decrease in arterial compliance in young, middle aged and older adults (Gates et al., 2003:2213; Havlik et al., 2003:156; Seals, 2003:68; Moreau et al., 2003:865; Joyner, 2000:1214; Cameron et al., 1999:653). The objective of this study was firstly to determine the correlation between obesity and vascular function in Caucasian women between the ages 19 and 56 and to determine which marker of obesity is the best predictor of a weakened vascular function (see article one). The second objective was to determine the correlation between physical activity, obesity and arterial compliance in Caucasian women between the ages 19 and 56 years (see article 2). A total of 115 Caucasian women were recruited to participate in this study. Anthropometric measurements and a comprehensive body composition profile was taken using the BOD POD. The Finometer apparatus was used to measure the arterial compliance and the sphygmomanometer to measure the subjects blood pressure. The subjects completed the Yale Physical Activity Survey questionnaire to determine their physical activity index. This study seems to indicate a positive relationship between arterial compliance and obesity which could be explained by the influence blood volume had in determining arterial compliance. A negative correlation was found between obesity and blood pressure where an increase in obesity caused an increase in both systolic and diastolic blood pressure. A positive correlation was found between physical activity and obesity. The higher the activity levels were in this study, the less obese the subjects tended to be. No correlation was found between physical activity and arterial compliance. A clear trend, even though no statistically significant differences, was found between physical activity and blood pressure. The more active the subjects were, the lower their blood pressure tended to be. / Thesis (M.Sc. (Human Movement Science))--North-West University, Potchefstroom Campus, 2005