UNDERWATER WEIGHING
UNDERWATER WEIGHINGGROUP MEMBERS:AMIR IKRAM BIN RAHIMNORAZAH BT ABU BAKARNOOR FAIZAH BT NASRUDINNUR HAZSHILA BT ABD HADI
UNDERWATER WEIGHINGAlso called hydrostatic weighingA method of determining body composite (body fat to lean mass) that make up a persons total body density using Archimedes Principles of displacement.According to Archimedes principle, when a body (person) is submerged under water, the weight a body loses underwater equals the weight of the water it displaces.
Hydrostatic Weighing
Hydrostatic weighing, also known as Hydrodensitometry or underwater weighing, is a classic measure of body composition.
Purposethe aim of underwater weighing is to measure the density of the body, and from that figure calculatepercentage body fat
Equipment requiredHydrostatic stainless steel weighing tankUnderwater mounted chair
3) Weighing Scale
4) weighted belt5) nose clip
6) Thermometer7) Water density chart
ProcedureThe subject wears the test attire (minimal clothing)The dryweightof the subject is first determined
3. The subject should totally wet their whole body before sitting on the specialized chair.
4. The subject then sits on a specialized seat, expels all the air from their lungs, and is lowered into the tank until all body parts are emerged.
5. The person must remain motionless underwater while the underwater weight is recorded. 6. This procedure is repeated three times to get a dependable underwater weight measure. See videos aboutHydrostatic Weighing.
Density of bodyDensity of waterWeight of immersed bodyWeight of body in air=Weight of body in air____________-xBODY DENSITY CALCULATION
AdvantagesUnderwater weighing is the most widely used test of body density and in the past was the criterion measure for other indirect measures
DisadvantagesThe equipment required to do underwater weighing is expensive. The tanks are mostly located at university or other research institutions, and there is generally not easy access for the general population.
ValidityThis method may underestimate body fat percentage of athletes as they tend to have denser bones and muscles than non-athletes, and may overestimate body fat percentage of elderly patients suffering from osteoporosis.
**comments:The water temperature is often elevated to provide a comfortable experience for the subject, however the density of water is dependent on the temperature and should be factored into the equation.
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