Disruption of the normal rheological properties of blood is considered an independent risk factor for cardiovascular disease and plays a significant role in the aetiology of atherothrombogenesis. The acute increase in whole blood viscosity may unfavourably affect the microcirculatory blood flow and oxygen delivery to the tissues. It is universally accepted that exercise and physical activity performed on a regular basis has health benefits. However, the effects of exercise on the rheological properties of blood have not received much research attention. Recent, limited evidence indicates that the viscosities of whole blood and plasma increase in response to a variety of exercise protocols. The increase in whole blood viscosity is mainly attributed to an increase in haematocrit and plasma viscosity, whereas the deformability and aggregability of red blood cells remain unaltered. The increases in plasma viscosity and haematocrit have been ascribed to exercise-induced haemoconcentration as a result of fluid transfer from the blood to the interstitial spaces. The haemorheological changes associated with strenuous exercise appear to be linked with enhanced oxidative stress and depletion of antioxidant capacity, and that may affect oxygen delivery and availability to the tissues. Although significant advances have been made in many areas of exercise haematology, the long-term effects of endurance training on blood rheology have been very briefly examined and the exact effect of training has not as yet been determined. Available cross-sectional and longitudinal studies indicate that the blood of endurance athletes is more dilute and this has been attributed to an expansion of blood volume, particularly plasma volume as a result of training. The low haematocrit values in trained athletes represent a hydration condition rather than iron stores deficiency. It has been suggested that this hypervolaemia and blood dilutional effect of endurance training may be advantageous for heat dissipation and greater cardiac stroke volume and lower heart rates during exercise. Enhanced blood fluidity also facilitates oxygen delivery to the exercising muscles because of a reduced resistance to blood flow within the microcirculation. Furthermore, the increase in plasma volume may contribute to the body water pool and help offset dehydration. The influence of strength and power training on blood rheology is not known. The physiological mechanisms responsible for and the functional consequences of the haemorheological changes associated with exercise to a large extent remain speculative. The paradox of haematocrit and blood rheology in exercise and training warrants additional studies. Likewise, further investigations are necessary to determine the possible link between overtraining and blood rheological profiles.
Higher education is moving with deliberate speed to an electronic classroom. Much has been published on faculty experiences with World Wide Web (WWW) course delivery. However, little research exists on the evaluation of these methods. The purpose of this study was to evaluate students' perceptions of two approaches to teaching: classroom and WWW modules. Classroom methods were rated significantly higher in relation to content, interaction, participation, faculty preparation, and communication. Technical skills were rated higher for WWW modules. Critical thinking and time allotted for assignments were not significantly different between classroom and WWW instruction. Open-ended comments were rich and supported both positive and negative aspects of classroom and WWW-based modules. Implications call for creativity in course development, course redesign and orientation, active communication with students, support for technical problems, faculty development, and university-wide planning through partnerships.
Coronary heart disease (CHD) risk increases with age, and this increase is more dramatic in women than men. The incidence of CHD is lower in premenopausal women compared with men. After menopause, the risk of mortality from CHD increases in women. The purpose of this study was to test predictors of CHD preventive behaviors using an adapted form of the Health Belief Model (HBM) in a sample of 178 women. The predictor variables were perceptions of susceptibility to CHD, perceptions of seriousness of CHD, general health motivation, social support, and knowledge of risk factors of CHD. Regression results revealed that susceptibility to CHD, seriousness of CHD, knowledge of risk factors of CHD, and general health motivation together explained 76% of the variance of CHD behaviors. Implications for future research and for improving education about consistent adoption of CHD preventive behaviors are discussed.
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