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Dissertation submitted in compliance with the requirements for Masters Degree in Technology in the Department of Electrical Engineering, Technikon Natal, 2000. / The purpose of this study is the development of an affordable computer-based electrocardiogram, heart rate and temperature monitoring system, that would complement those that are available on the market and contribute to the reduction of the shortage of these medical instruments in South African hospitals and clinics. Electrocardiogram (ECG) refers to the graph that results from time versus voltage in a patient's chest. It reflects the rhythmic activity of the heart. For this reason the electrocardiogram has a diagnostic value that can be used by medical personnel to examine the biological (hence, clinical) behavior of the heart. The electrocardiogram can also be used to get the heart rate. This thesis explained how to acquire ECG signals from the patient and also how to achieve a cheaper way of providing galvanic isolation, which is required for sensors that are attached to the human body. It also explains computer interfacing using the parallel port and computer-based processing of these ECG signals to determine the instantaneous value of the heart rate and also to reduce the interference that contaminates these signals. In reducing interference, the performance of traditional IIR notch and adaptive filters, as noise cancelers, has been analyzed and compared. Least Mean Squares (LMS) and Normalized Least Mean Squares (NLMS) algorithms are the two algorithms that were considered in this study for adaptive noise canceling and their performance is evaluated and is compared based on their convergence rate, complexity and noise reduction. / M

There is growing concern that many children in Britain do not take sufficient exercise to benefit cardiovascular health. This is supported by extensive evidence advocating the importance of regular physical activity for lifelong health and well-being, and is of particular relevance in Scotland given it's notorious record of adult coronary heart disease death. This study examined aspects of fitness and physical activity in groups of Edinburgh school children, aged between 13 and 14 years. A three stage investigation was adopted: Phase One: A repeated measures, same subject design was used to examine the reliability and validity of selected measures (20m shuttle run test, peak oxygen uptake (V02 Peak), and anthropometric measures). Thirty three children (15 boys, 18 girls) performed each test on 3 separate days. Anthropometric measures showed strong reliability (r > 0.94, n=33) whilst reliability for the treadmill test ofV02 peak and shuttle run performance was lower (r=0.89 and r=0.79 respectively). Multiple regression analysis yielded a new equation for predicting V02 peak for children. This age specific prediction equation incorporated shuttle run performance in conjunction with skinfold thickness measures (Boys, R2=0.64 SEE=3.46; Girls, R2=0.79, SEE=2.81). Repeat testing was also recommended. Phase Two: An evaluation of methods of heart rate data analysis to assess physical activity in children. Twenty eight children (14 boys, 14 girls) wore continuous heart rate monitors (polar Electro PE4000, Finland) over a period of 7 days (Monday to Sunday), mean duration 737 (+/-55) mins/day. A detailed 7 day self report activity diary was also completed. Variability of heart rate measures was high (R=0.10-0.30), and it was noted that using data for just 4 days or less resulted in considerable underestimation of total weekly activity levels (44-100% error). If activity levels are to be compared against current recommendations, researchers must endeavour to achieve weekly rather than daily estimates of activity. Evaluation of methods of heart rate data analysis showed good correlation between heart rate activity indices and reported seven day activity. For boys strongest correlation was achieved using the number of 5 minute periods with HR > 139 b.min"l and the number of 5 minute periods with HR > 50% heart rate reserve (r=0.80, n=14). Total activity time was similar for both males and females but girls engaged in fewer sustained bouts of activity (>5 minutes) and a better correlate with activity in females was achieved using the total number of elevated heart rates (total HR > 50% heart rate reserve, r=0.64, n=14). Phase Three: A cross sectional survey was conducted to investigate standards of aerobic fitness and patterns of physical activity in groups of Edinburgh school children. Height, weight, skinfold thickness, shuttle run performance and physical activity (assessed by heart rate monitoring and activity diary) were recorded in a sample of 91 children (44 Boys, 47 Girls). Overall, males performed significantly better on the shuttle run test (t=5.4, df=88, p < 0.05), had higher predicted peak oxygen uptake (t=5.6, df=87, p < 0.05), and engaged in more bouts of moderate to vigorous activity than females. Seventy percent of boys and 50% of girls fulfilled current physical activity guidelines. Most activities were school based (131 mins per week as compared to 85 mins per week of out of school activities). Activity tended to be sporadic with active days interspersed with inactive days (mean 3.2 +/·1.6 days per week). After school activities specifically targeting young girls should be promoted.

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