Body Fat Lab Report Essay

Introduction Hydrostatic weighing is an indirect measurement used to predict body fat percentage. It is typically the most accurate means of determining body fact percentage, and is based on measuring an individual’s body density. Archimedes' principle explains that the upward buoyant force exerted on a body immersed in a fluid is equal to the weight of the fluid that the body displaces. Due to the fact that body fat is less dense than water, it increases one's buoyancy, while the fat-free mass is denser than water, and which makes one sink. This allows percent fat to be calculated after correcting for residual volume, which increases buoyancy and decreases the underwater weight. Measuring fat mass is important with the understanding of essential
The predetermined value for gastrointestinal air was calculated at 100ml. The female subject was 22 years old and measured a weight of 56.6kg and a height of 165.1cm. Using a predetermined vital capacity of 4000ml, the subjects’ residual volume was calculated by multiplying 4000 by 0.28 for a gender specific estimation of 1120ml. The steps used to conduct the lab are as
This value was found by subtracting 0.7kg, due to the weight of the harness, from the measured 1.2kg during full immersion underwater. The values for body mass in air and water were converted to grams by multiplying by 1000. This gave an end body mass in air of 56,600 g and body mass in water of 500g. These values were used along with residual volume, GI air, and water density to determine the subjects’ body density. Using the equation [56,600g Body Mass Air] / [((56,600g Body Mass air – 500g Body Mass Water) / 0.9957g/ml Water Density) – (1120ml RV + 100ml GI air)] the body density was found to be 1.03g/ml. This value was then used in the Siri and Brozek equation to determine fat percentage. The Siri equation (495 / 1.03g/ml Body Density) – 450 depicted a fat percentage of 32.08%. Additionally, the Brozek equation (457 / 1.03g/ml Body Density) -414 resulted in a fat percentage of 29.69%. The following tables depict how the water density was determined and the body mass records of the test