Die verband tussen morfologiese indekse en risiko-indikasies vir deelname aan fisieke aktiwiteit

Abstract

The Relationship between some MorPholo!!ical Indices and Indications of Risk for Participation in PhYsical Activity The Problem and Purpose of this Research - Excess body fat, or obesity affects the state of health in several ways through associated physiological abnormalities. Research has proved that obesity is associated with abnormalities such as hypertension, diabetes mellitus, disturbances in the concentration and composition of cholesterol, as well as the prevalence of coronary heart disease. The research done by Vague between 1940 to 1950 cleared the way for the belief that the site or location of fat deposits in the body was of more importance than the mere existence of fat. It has since been determined that the android type of obesity was to a greater extent associated with the prevalence of diabetes, gout and arteriosclerosis than the genoid type of obesity. The precise mechanism through which the domination of fat in the abdominal region triggers off all of these derangements is mainly due to the differences in metabolic activity between fat in different parts of the body. Both subcutaneous and visceral fat situated in the abdominal area is to a larger extent involved in the metabolic processes which result in an elevated concentration of triglycerides in the plasma. This by-product leads through a process of multiple physiological interactions to adverse levels of lipids, lipoproteins and insulin, which are predicative of coronary heart disease.

Since both the ratio of waist-to-hip circumferences and the body-mass index (Quetelet v index) correlates with some risk factors as well as diseases such as diabetes, arteriosclerosis and coronary heart disease, the question arises if it would be possible to determine the latter threats to good health by determining a few anthropometrical variables. This study will evaluate the relationship between these anthropometrical variables as independent variables, with the concentration and composition of cholesterol, and some physical variables as dependent variables in a South African community. Methods - The stratified random sample of participants between the ages of 16 and 64 years were drawn from the white male and female population of the two industrialized communities, Vanderbijlpark and Witbank. The participants were contacted by telephone and were given the choice to refuse participation. Before taking part in the physical part of the project, a comprehensive medical and physical history questionnaire was completed in order to point out any underlying risk factors to physical activity. All the participants had to sign an informed consent to ascertain that the participant is aware of the small, but real risk of exercise testing, and to obtain evidence that their participation in the event was with permission. The following variables were determined: * Age was notated to the nearest year. * The stature and body mass from which the Quetelet index was calculated. * The waist circumference and hip circumference from which the ratio of the waist-to-hip circumferences was determined.

* Blood samples were taken, and the HDL-C, and LDL were precipitated from the serum, and after centrifugation the cholesterol content of the supernatant was determined. * The physical working capacity per kg body weight was determined using a cycle ergometer. * The index of physical activity which is based on the intensity, duration and frequency of physical activity, was calculated from data concerning the state of activity within the career/school and after hours. Statistical analysis was conducted by using the Statistical Analysis System (SAS) computer programme. The significance of correlations between the independent and dependent variables, as well as the percentages resulting from the calculation of the r2 index was used as an indication of the extent to which risk factors for coronary heart disease could be predicted from a simple set of anthropometrical measurements. Results - The results with regard to the men indicated that: * A significant correlation exists between both the waist-to-hip circumference ratio and the Quetelet index with the total cholesterol, and the TC/HDL-C ratio. None of the other correlations were significant, and therefore have no direct application in practice. * The Quetelet index in general gives the most successful indication of the risk factors that were evaluated. The results with regard to the women indicated: * No significant correlation could be indicated between both the waist-to-hip circumference ratio and the Quetelet index with any of the risk factors for coronary heart disease that were determined in this study.

* In all, but one of the cases the Quetelet index had a better correlation with the risk factors than the waist-to-hip circumference ratio. * The magnitude of all the correlations leads to the assumption that neither of the "/ two morphological indices could be used to determine the presence of the determined risk factors for coronary heart disease.