HOW DOES THE BOD POD WORK?
By Jamie Wilkins | Fitness General Manager | INenergy | MEDICAL
Considered the gold standard in body composition technology, the BOD POD is fundamentally the same as underwater (hydrostatic) weighing, but uses air instead of water. It measures the volume of air a person’s body displaces while sitting inside the chamber, rather than measuring how much water his or her body displaces when dunked in a tank.
A BOD POD test is included free of charge with the purchase of 10 personal training sessions, as part of our INLIV advanced fitness assessment. BOD POD testing may also be purchased on its own and is available to the public. No membership is required.
Since it is based on the same whole-body measurement principle as hydrostatic weighing, the BOD POD first measures the subject’s mass and volume. From these measurements, whole-body density is determined. Using this data, body fat and lean mass can then be calculated.
The BOD POD is a dual-chambered, plethysmograph that determines body volume by measuring changes in pressure within a closed chamber. The front, or test chamber, has a seat that forms a common wall separating it from the rear, or reference chamber. The door to the front chamber is secured by a series of magnets during the brief data collection period.
The system measures body composition by determining body volume and body weight. Once those two variables are determined, body density can be computed and inserted into an equation to provide percent fat measurements. Body weight is determined by the use of an accurate scale. Body volume is determined by applying the gas law (p1V1=p2V2), an expansion of Boyle´s Law, pV=c. The BOD POD measures volume by monitoring changes in pressure within the closed chamber. These pressure changes are achieved by oscillating a diaphragm, which is mounted between the front testing chamber and the rear reference chamber, causing complementary pressure changes in each chamber.
The volume of the subject chamber while empty is the first measurement taken by the BOD POD. The second measurement is the volume of the subject chamber with the subject inside. By subtraction, the volume of the subject is determined. Combined with the measurement of mass, the subject´s density is determined, and subsequently, their body composition is established.
WHY IS IT IMPORTANT TO WEAR PROPER CLOTHING WHILE IN THE BOD POD?
The BOD POD takes very accurate measurements of your weight and volume (the size of your body). Anything that isn’t “you”, including clothing, jewelry, or eyeglasses, can produce inaccurate results. This is why it’s important you wear minimal, form-fitting clothing such as a lycra or Spandex® swimsuit. Single-layer compression shorts and/or lightweight jog bras (without padding or wires), are also acceptable clothing. A swim cap must also be worn to compress any air pockets within the hair.
At INLIV, BOD POD body composition testing is available as part of our advanced fitness assessment, and may also be purchased separately. To track your progress, a series of three BOD POD tests are available at a special rate, or choose a BOD POD plus V02 Max combination assessment. Click here for more information on the body assessment and training packages available.