Physical activity is a powerful modifiable lifestyle factor that reduces the risk of cardiovascular disease (CVD) in adults through favorable changes in conventional risk factors including serum lipids, blood pressure and glycemia. Recent evidence suggests that the cardioprotective effects of physical activity may also be mediated through beneficial effects on vascular function, in particular arterial stiffness. While the beneficial effects of physical activity in CVD risk in adults are irrefutable, data in youth are limited, especially for arterial stiffness. Purpose: The purpose of this project is to explore the continuous association between physical activity and arterial stiffness in youth. Hypothesis: We hypothesized that physical activity is negatively associated with arterial stiffness, whereby highly active youth would display lesser degrees of arterial stiffness than their less active (sedentary) peers. Methods: 485 youth (12-13 yrs) were recruited from the 1995 Manitoba birth cohort involved in the GreatICE asthma and allergy study. Youth were stratified into tertiles (high, medium, low) of self-reported physical activity. Global cardiometabolic risk was determined from a composite score of conventional risk factors including, LDL, SBP, Insulin, Glucose and Triglycerides. Arterial stiffness was assessed non-invasively using conventional pulse wave analysis and velocity. Results: Of the 485 youth who participated in this wave of the study, measures of PWV and PWA were available on 357 and 335 youth respectively. Cardiometabolic risk decreased with increasing levels of vigorous physical activity. Neither measure of arterial stiffness was associated with physical activity. Conclusion: Increased vigorous physical activity is associated with reduced cardiometabolic risk in youth independent of arterial stiffness.

Physical activity is a powerful modifiable lifestyle factor that reduces the risk of cardiovascular disease (CVD) in adults through favorable changes in conventional risk factors including serum lipids, blood pressure and glycemia. Recent evidence suggests that the cardioprotective effects of physical activity may also be mediated through beneficial effects on vascular function, in particular arterial stiffness. While the beneficial effects of physical activity in CVD risk in adults are irrefutable, data in youth are limited, especially for arterial stiffness. Purpose: The purpose of this project is to explore the continuous association between physical activity and arterial stiffness in youth. Hypothesis: We hypothesized that physical activity is negatively associated with arterial stiffness, whereby highly active youth would display lesser degrees of arterial stiffness than their less active (sedentary) peers. Methods: 485 youth (12-13 yrs) were recruited from the 1995 Manitoba birth cohort involved in the GreatICE asthma and allergy study. Youth were stratified into tertiles (high, medium, low) of self-reported physical activity. Global cardiometabolic risk was determined from a composite score of conventional risk factors including, LDL, SBP, Insulin, Glucose and Triglycerides. Arterial stiffness was assessed non-invasively using conventional pulse wave analysis and velocity. Results: Of the 485 youth who participated in this wave of the study, measures of PWV and PWA were available on 357 and 335 youth respectively. Cardiometabolic risk decreased with increasing levels of vigorous physical activity. Neither measure of arterial stiffness was associated with physical activity. Conclusion: Increased vigorous physical activity is associated with reduced cardiometabolic risk in youth independent of arterial stiffness.

This research assessed the role of Hatha yoga in the modulation of vascular health. In study one, Hatha yoga practitioners were compared to sedentary controls to whom they were matched for age and body mass index. Practitioners of Hatha yoga were no different from sedentary individuals in terms of arterial stiffness or vascular endothelial function. Yoga practitioners possessed lower HbA1c (P < 0.05) levels and lower pulse pressure (P < 0.05) than their sedentary counterparts. Practitioners of Hatha yoga had lower body fat percentages, but this observed trend did not reach statistical significance (P = 0.052). In study two, a 12-week Hatha yoga intervention resulted in reductions in HbA1c levels (P < 0.05) and total cholesterol (P < 0.05) in previously sedentary adults. No changes were observed in carotid artery compliance or brachial artery flow-mediated dilation as a result of the intervention. In study three, obese and lean, apparently healthy adults completed an 8-week Bikram yoga intervention. Reductions in total- and LDL-cholesterol were observed in the lean subjects (P < 0.05), with no changes in lipid profiles in the obese group. The homeostasis model assessment of insulin resistance (HOMA-IR) decreased in the lean subjects, but this trend did not attain statistical significance (P = 0.06). Although an observed trend was shown at 60 minutes during the oral glucose tolerance test (P = 0.07), glucose tolerance remained unchanged in the obese subjects. Brachial artery flow-mediated improved by approximately 2% in the obese subjects, but this observed change did reach statistical significance (P = 0.10). Flexibility increased in both groups as a result of the Bikram yoga intervention. Therefore Hatha yoga improved lipid profiles and glycemic control in sedentary adults, but no effects on vascular health were demonstrated. / text

Master of Science / Department of Kinesiology / Carl Ade / Background – Chemotherapy-induced left ventricular cardiotoxicity is associated with many cancer treatments; however, what is less known is how these treatments affect vascular health and autonomic control of blood pressure. Arterial stiffness and cardiovagal baroreflex sensitivity (BRS) are indicators of cardiovascular health and may provide insight into the adverse effects of anti-cancer chemotherapy. Therefore, the primary aims of the present study were to evaluate carotid artery stiffness and arterial BRS in cancer patients currently being treated with adjuvant chemotherapy. Methods – We performed a cross-sectional, case-control study involving 9 cancer patients and 9 age- and sex-matched controls. Carotid artery stiffness was assess via 2D ultrasonography. Cardiovagal BRS was assessed from the spontaneous changes in beat-to-beat time series of R-R interval and systolic blood pressure via the cross correlation technique. Results – Our findings indicated a significant decrease in cardiovagal BRS in cancer patients compared to controls (4.7 ± 0.6 vs 9.2 ± 1.7 msec mmHg⁻¹ respectively, P = 0.02). Carotid artery β-Stiffness was significantly higher in the cancer patients compared to control participants (9.2 ± 1.2 vs 6.6 ± 0.74 U respectively, P = 0.05). Conclusions – These data suggest that anti-cancer chemotherapy elicits significant decreases in the autonomic control of blood pressure and arterial stiffness, leaving cancer survivors with an increased risk of future cardiovascular disease.

Cardiovascular disease (CVD) is the leading cause of death in the United States. Recently, the gut microbiota has been implicated in the pathophysiology and progression of CVD. Experimental evidence suggests that high fat feeding alters the functional composition of the gut microbiota (dysbiosis); leading to increased translocation of the pro-inflammatory, endotoxin, and increased production of the pro-atherogenic, trimethylamine-N-oxide (TMAO). Together, these changes are hypothesized to accelerate CVD progression. Conversely, administration of gut microbiota modulating agents, such as antibiotics and probiotics, attenuate high fat feeding induced CVD in rodent models. In humans, the capacity to produce TMAO following L-carnitine or phosphatidylcholine challenges is abolished after receiving broad spectrum antibiotics for a period of one week. However, whether gut modulation over a longer period of time decreases fasting serum endotoxin, fasting plasma TMAO, and CVD risk in response to high fat feeding has been unexplored in humans. To address these issues we conducted a randomized, placebo controlled, parallel group designed, controlled feeding study in healthy, non-obese males receiving the multi-strain probiotic, VSL #3 (or placebo), while a consuming a high fat diet for 4-weeks. First, we tested the hypothesis that VSL #3 would attenuate the rise in serum endotoxin and consequent arterial stiffening following high fat feeding in healthy, non-obese males. Second, we tested the hypothesis that VSL #3 would attenuate the rise in plasma TMAO concentrations following high fat feeding in healthy, non-obese males. In contrast to our first hypotheses, serum endotoxin concentrations and arterial stiffness did not change in response to high fat feeding or with VSL#3 treatment. Interestingly, VSL #3 significantly attenuated the increase in body mass (+ 1.4±0.4 vs. +2.3±0.3 kg; P < 0.05) and fat mass (+0.7±0.1 vs. + 1.4±0.3 kg; P < 0.05) following high fat feeding compared to the placebo. In contrast to our second hypothesis, probiotic supplementation did not attenuate the rise in plasma TMAO following high fat feeding. Future studies are necessary to elucidate the mechanisms responsible for the prevention of body mass and fat mass gain with VSL#3 supplementation following high fat feeding. In addition, studies are needed to determine whether higher doses of VSL #3, other single or multispecies probiotics, prebiotics, or synbiotics attenuate the production of the proatherogenic, TMAO. / Ph. D.

Background. Stroke affects over 80 million individuals worldwide. Elevated arterial stiffness has emerged as a novel independent risk marker for stroke. While arterial stiffness is improved after chronic aerobic training, a single bout of aerobic exercise leads to transient increases that typically resolve within 5 minutes of recovery. Elevated arterial stiffness may persist for up to 30 minutes following exercise in populations with cardiovascular disease. However, no study has examined the effect of acute aerobic exercise on arterial stiffness and central hemodynamics in individuals with stroke. Moreover, no study has explored the clinical significance of these responses. Objectives. The primary objective of this thesis was to characterize the response and recovery of arterial stiffness and central hemodynamics to peak aerobic exercise in individuals ≥ 6 months post-stroke. The secondary objective was to explore the relationships between the exercise response and recovery of arterial stiffness and central hemodynamics, with cardiorespiratory fitness and walking ability. Results. This cross-sectional study recruited 10 adults with stroke (mean ± SD age=56.9 ± 11.8; median [IQR]= 2.9 [1.9] years post-stroke; n=4 females). After peak aerobic exercise, cfPWV increased from rest and remained elevated for 20 minutes (p<0.05). Heart rate increased and remained elevated for 10 minutes post-exercise (p<0.05), while systolic blood pressure decreased and remained reduced for 15 minutes (p<0.05). Positive associations were found between cardiorespiratory fitness and heart rate reserve (r=0.74, p=0.02), and with each phase of heart rate recovery (HR60s r=0.80, p=0.005, HR120s r=0.79, p=0.006; HR300s r=0.72, p=0.02; and HR600s r=0.75, p=0.01). There were no relationships between response and recovery of hemodynamic variables with walking ability. Conclusion. Individuals with chronic stroke may have impaired arterial stiffness and heart rate recovery following peak aerobic exercise. Moreover, heart rate reserve and all phases of heart rate recovery were related to cardiorespiratory fitness, but not walking ability. / Thesis / Master of Science Rehabilitation Science (MSc) / Arterial stiffness has been recently identified as an important risk marker for stroke. Aerobic exercise reduces the risk of stroke by lowering arterial stiffness. But during exercise, there is an increase in arterial stiffness that usually subsides by 5 minutes. Lengthy exposure to arterial stiffness can cause damage to organs like the kidneys and liver. The purpose of this thesis was to measure the arterial stiffness and cardiovascular response to exercise in people with stroke. We also studied the relationship between the responses, fitness and walking ability. Ten people with stroke participated in this study. After aerobic exercise, arterial stiffness stayed high above resting levels and did not recover after 20 minutes. Also, heart rate recovery was related to fitness but not walking ability. This study tells us that people with stroke have an weakened ability to recover from aerobic exercise and that higher fitness levels can improve exercise recovery.

Photoplethysmography (PPG) is a simple means of measuring the pulse wave in humans, exploitable for the purposes of timing the arrival of the pulse at a particular point in the arterial tree, and for pulse contour analysis. This thesis describes a methodology for measuring arterial pulse transit time (PTT) from cardiac ejection to pulse arrival at the finger. It describes the effect on PTT of drug and exercise induced changes in BP. The nature of the relationship between the PPG and arterial pressure is also examined, and the PTT technique extended to assessment of conduit vessel pulse wave velocity (PWV) during exercise. PTT measured from ECG R-wave to PPG finger wave (rPTT) had a negative correlation (R2=0.39) with systolic BP (SBP), unaffected by vasoactive drugs in some but not all persons. rPTT showed similar beat-to-beat variability to SBP, unaffected by drugs. rPTT correlated weakly with diastolic (DBP) and mean (MAP) pressure. Cardiac pre-ejection period (PEP) formed a substantial and variable part of rPTT (12% to 35%). Transit time adjusted for PEP (pPTT) correlated better with DBP (R2=0.41) and MAP (R2=0.45), than with SBP. The PPG wave tracked changes in the peripheral pressure wave. Drugs had little effect on the generalised transfer function (GTF) describing the association between arterial and PPG waves. Strenuous exercise induced a large decrease in rPTT, mainly accounted for by decreases in PEP (53% of the total change in rPTT) and in transit time from aorta to distal brachial artery (33%). In contrast, minimal change in transit time from wrist to finger tip occurred with exercise. Simultaneous ear-finger PPG signals were used to measure conduit artery PWV during exercise. Ear-finger PWV (PWVef) overestimated carotid-radial PWV throughout exertion (overall bias 0.81±1.05ms-1, p<0.001), but the degree of difference remained constant. The increase in PWVef with exercise, was greater (1.18±0.54ms-1, p=0.035) in healthy subjects with a positive cardiovascular family history compared to those without. PPG enables analysis of the pulse contour during exercise, but estimation of the radial pressure wave from finger PPG by use of a GTF derived at rest, resulted in inaccuracy following exertion. These effects were variable and relatively short-lived. Furthermore, a resting GTF used to determine central pressure from the peripheral wave, resulted in underestimation of SBP (-5.9±2.1mmHg) and central pressure augmentation index (-8.3±2.9%), which persisted for 10 minutes post-exercise. rPTT had a negative linear association with SBP (R2=0.94) during strenuous exercise, slightly stronger than during recovery (R2=0.85). Differences existed in area-undercurve of the rPTT/SBP relationship between exercise and recovery, due to discrepancies in rate and degree of recovery of SBP and PEP. The linear relationship between the rPTT/SBP during exercise was affected by aerobic capacity, and the regression slope was less in the anaerobic compared to aerobic phase of exercise due to minimal change in PEP during anaerobic exertion. The correlation between rPTT/SBP did not change with prolonged aerobic exercise. Finally, measures of baroreflex sensitivity during exercise, were not significantly different between actual beat-to-beat SBP and SBP estimated using rPTT. In conclusion, absolute BP cannot be reliably estimated by measurement of rPTT following administration of drugs and during exercise. However, rPTT may have a role in measuring BP variability and in the assessing exercise capacity. PPG may also be useful in determining the effects of exercise on arterial stiffness, and for estimating the pressure wave contour, although its use during exercise for the latter purpose must be treated with caution.

The largest percentage of mortality from tobacco smoking is cardiovascular-related. It is not known whether regular participation in exercise mitigates the adverse influence of smoking on vasculature. The purpose of this study is to determine if regular aerobic exercise is associated with reduced arterial stiffness in young men who are cigarette smokers. Using a cross-sectional observational study design, the sample included 78 young men (22±5 years) with the following classification: sedentary smokers (n=12); physically active smokers (n=25); sedentary non-smokers (n=20); and physically active non-smokers (n=21). Arterial stiffness was assessed by brachial-ankle pulse wave velocity (baPWV). There were no group differences in height, body fatness, systolic and diastolic blood pressure. As expected, both physically active groups demonstrated greater VO2max and lower heart rate at rest than their sedentary peers. The sedentary smokers demonstrated greater baPWV than the sedentary non-smokers (1,183±33.5 vs. 1,055±25 cm/sec). baPWV was not different between the physically-active smokers and the physically-active non-smokers (1,084±26 vs. 1,070±28.6 cm/sec). Chronic smoking is associated with arterial stiffening in sedentary men but a significant smoking-induced increase in arterial stiffness was not observed in physically active adults. These results are consistent with the idea that regular participation in physical activity may mitigate the adverse effect of smoking on the vasculature. / text

Age is the major risk factor for cardiovascular diseases (CVD) and this is attributable in part to stiffening of large elastic arteries and development of vascular endothelial dysfunction. In contrast, regular aerobic exercise is associated with reduced risk of CVD. Swimming is an attractive form of aerobic exercise and always recommended for health promotion as well as prevention and treatment of risk factors for CVD. However, there is little scientific evidence to date indicating that swimming is equally efficacious to land-based exercise modes in reducing cardiovascular risks. Accordingly, the aim of the research was to determine the role of regular swimming exercise on both CVD traditional risk factors and vascular functions. To comprehensively address this aim, 2 different approaches were used: Study 1 (cross-sectional study) was designed to determine the potential benefit of regular swimming exercise in the primary prevention of age-related decreases in vascular function. Key measurements of vascular function were performed in middle-aged and older swimmers, runners, and sedentary controls. Central arterial compliance was higher in swimmers and runners than in sedentary controls. Study 2 (intervention study) was designed to determine whether regular swimming exercise could reverse the age-associated decline in vascular function. Middle-aged and older subjects completed either a 12-week swim training program or relaxation/ stretching exercise (attention control) program. Short-term swim training improved arterial blood pressure and vascular functions. In summary, regular swimming exercise can attenuate reductions in and partially restore the loss of vascular function including central arterial compliance and endothelial function in middle-aged and older adults. Swimming exercise exhibited typical central arterial compliance and endothelial function phenotypes that are often displayed in land-based exercise. / text

Made available in DSpace on 2014-06-11T19:32:59Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-07-30Bitstream added on 2014-06-13T19:43:54Z : No. of bitstreams: 1 macedo_mls_dr_botfm_prot.pdf: 3586847 bytes, checksum: 528671d32509cb0d8b738be7fcab29b3 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / A hipertensão gestacional está presente em cerca de 10% das gravidezes e ainda é a primeira causa de mortalidade materna no Brasil. O diabetes gestacional complica 7,6% das gestações no Brasil e está associado a esultados perinatais insatisfatórios. Estas complicações cursam com disfunção endotelial e alteração da elasticidade da parede -.vascular. A onometria de aplanação é um método não invasivo, portátil e de fácil aprendizagem que avalia a função endotelial através do estudo da rigidez arterial (perda da elasticidade arterial). Além de avaliar a função endotelial este método oferece estudo indireto de vários parâmentros cardiovasculares centrais. O grande número de informações que este método obtém de maneira não invasiva, faz deste, um instrumento valoroso em pesquisa. Apresenta grande potencial, especialmente, na compreensão dos mecanismos fisiopatológicos que cursam com comprometimento vascular na gravidez. / Gestational hypertension affects 10% of pregnancies and is still the first :ause of maternal mortality in Brazil. Gestational diabetes affects 7,6% of gnancies in Brazil and is associated with an unsatisfactory peri-natal come. These complications are associated to endothelial dysfunction and abnormal elasticity of the arterial wall. Applanation tonometry is a nonvasive, portable and easy learning method that evaluates endothelial nction by the study of arterial stiffness (Iost of arterial elasticity). Beyond e endothelial function evaluation, this method gives, indirectly, several central cardiovascular parameters. The great number of information btained non invasively by this method, makes of this, a valuable instrument in research. It has special potential to help in the comprehension of the mechanisms of those diseases that presents with vascular commitment in pregnancy.