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When coming to Bodyology for a BOD POD Analysis it is important, in order to ensure the accuracy of results, that you undertake the following measures:
- Do not eat for 2 hours before the test (You may drink small amounts of water to ensure normal hydration)
- Do not exercise for 2 hours before your appointment
- Wear appropriate clothing for the test (tight form fitting)
- Spandex, Lycra or other Speedo type swimsuit
- Spandex, Lycra or Skins type compression shorts and light weight sports bra (no padding or wires)
- It is recommended you wear this underneath comfortable loose clothing
- You will be required to wear a swim cap – Please bring your own if you have one. If not, one will be provided for you
- Use the restroom if necessary prior to testing
- It is recommended for women who carry excess water during different parts of their menstrual cycle, that testing during these times be avoided, and that retests occur at similar times to original tests.
Test Process
A BOD POD Gold Standard body composition assessment is extremely simple, comfortable, and takes only about 5 minutes.
The test sequence is as follows:
- Basic subject information is entered into the computer.
- The BOD POD is calibrated.
- The subject’s mass is measured using the integrated digital scale.
- The subject’s body volume is measured while sitting inside the BOD POD.
- The subject’s Thoracic Lung Volume (TGV) is either measured or a prediction equation is used.
- Test results are displayed, which can then be printed, saved, and/or exported.
View Test Demo
The information measured and produced in a BOD POD printout includes:
- Body Fat percentage
- Fat Free Mass percentage
- Absolute measurement Fat Mass (FM)
- Absolute measurement Fat Free Mass (FFM)
- Body Volume (L)
- Body Density (kg/L)
- Thoracic Gas Volume (L)
- Resting Metabolic Rate (RMR) Estimate based on FFM
- Total Energy Expenditure (TEE) Estimate based on Activity level and RMR
BODPOD Printouts
Pre-appointment preparation
Pre-appointment preparation
Extensive independent research has been published on the BOD POD. To view some of this and see the depth of research that the BOD POD has been involved in and the array of population groups it has been validated with visit Life Measurement Inc. at www.bodpod.com/research and follow the links.
Video footage and media coverage of the use of the BOD POD in different disciplines including medical research and elite sports programs (NFL in the U.S.A.) please visit www.bodpod.com/news/media.
The following information has been adapted from information provided by Life Measurement Incorporated, the developers of the BOD POD and Air Displacement Plethysmography.
How It Works
The BOD POD Gold Standard Body Composition Tracking System uses patented Air Displacement Technology for determining percent fat and fat-free mass in adults and children. The simple, 5-minute test consists of measuring the subject's mass (weight) using a very accurate electronic scale, and volume, which is determined by sitting inside the BOD POD chamber. Both mass and volume measurement devices are re-calibrated before every test to ensure accuracy, and strict Quality Control measures are performed every day before testing begins. From these two measurements, the subject's body composition is calculated.
The BOD POD consists of two chambers. The front, or Test Chamber, is where the subject sits and is comprised of a seat that forms a common wall separating it from the rear, or Reference Chamber. During the brief data collection period of the volume measurement, the chamber door is secured by a series of electromagnets and a gasket. A Diaphragm is mounted on the common wall, which oscillates during testing. This causes small changes in volume inside the chamber, of which the pressure response to these small volume changes is measured. This is done by measuring the interior volume of the empty BOD POD chamber, then measuring it again when the subject is seated inside. By subtraction, the subject's body volume is obtained. For example, if the interior air volume of the empty chamber is 400 litres, and the volume of the chamber is reduced to 350 litres with the subject inside, the body volume of the subject would be 50 litres.
Once the subject's mass and volume are determined, body density is calculated and the relative proportions of fat and fat-free mass are determined.
The most advanced technique for assessing body composition available today
The patented air displacement technology used by the BOD POD is similar in principle to hydrostatic ("underwater") weighing, previously referred to as the preferred Body Composition testing method. Hydrostatic weighing is predominantly only available through Universities and Research facilities in Australia. The obvious difference between the BOD POD and hydrostatic weighing is that air is more convenient and comfortable than water, so that Air Displacement Technology provides a much easier and safer testing environment, better reliability, and significantly improved repeatability and accuracy.
The basic operating principles of air displacement technology include Densitometry, Mass Measurement, Volume Measurement, Thoracic Gas Volume, and Surface Area Artefact.
Densitometry
With Air Displacement Technology, body composition is derived from body density, or Densitometry. In densitometry, the denser a body is, the lower the percentage of body fat. Therefore, the less dense a body is, the higher the percentage of body fat.
Densitometry is based on the division of the body into two compartments: a fat mass compartment and a fat-free mass compartment. The fat-free mass compartment consists of protein, water, mineral, and glycogen.
From the subject's body density, relative proportions of body fat and lean body mass are calculated based on the density of fat and lean tissue. Because lean tissue is denser than fat tissue, a higher density reflects a higher proportion of lean tissue.
A commonly used equation which translates whole body density to percent body fat is the Siri equation:
Percent Fat = [495/Density] - 450 |
Once the percent body fat is calculated, the percent lean body mass can also be determined as follows:
Percent Lean Body Mass = 100 - Percent Fat |
Mass Measurement
Mass (weight) is measured using a very precise, integrated electronic scale.
Volume Measurement
Volume is determined by Air Displacement Plethysmography (ADP), which occurs when the subject is inside the BOD POD chamber. ADP relies on the relationship between pressure and volume, and allows for the derivation of an unknown volume by directly measuring pressure.
During the volume measurement, small changes in volume occur inside the chamber, and the pressure response to these small volume changes is measured. This is done by measuring the interior volume of the empty chamber, then measuring it again when the subject is inside. By subtraction, the subject's body volume is obtained. For example, the interior air volume of the empty chamber is 400 litres; so if the volume of the chamber is reduced to 350 litres with the subject inside, the body volume of the subject would be 50 litres.
Thoracic Gas Volume
Because any air trapped in the subject's thoracic cavity, either free or trapped, is not part of their body volume, the air in the lungs must be accounted for. Using the BOD POD Gold Standard, Thoracic Gas Volume may be directly measured, retrieved from a previous test, predicted (using a standard prediction equation), or entered manually.
Surface Area Artefact
Due to isothermal behaviour, the volume of air in close proximity of the subject's surface is overestimated by 40%. This small Surface Area Artefact (an apparent reduction in the subject’s body volume) is automatically calculated by the BOD POD and used to correct subject body volume.
The surface area of clothing and hair can also have a significant impact on Volume measurements. It is extremely important that subjects tested using Air Displacement Technology wear minimal, form-fitting clothing and a cap to compress the hair on the head.
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