What does air displacement plethysmography primarily measure?

Air displacement plethysmography primarily measures body volume by calculating the volume of air displaced by a person's body when they are seated in a closed chamber. This technique is based on the principle of buoyancy and directly assesses the volume of the individual, which can then be used to derive estimates of body density and composition.

By accurately determining body volume, air displacement plethysmography allows for further calculations related to body fat and lean mass using additional data, such as body mass. While it is possible to derive information about body density and potentially draw implications about body composition, the fundamental measurement taken by this method is body volume itself.