How It Works
The BOD POD Express Body Composition Tracking System uses patented Air Displacement Plethysmography 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. 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 liters, and the volume of the chamber is reduced to 350 liters with the subject inside, the body volume of the subject would be 50 liters.
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.
