By Kirk Brumels and Maureen Dunn, Professors of Kinesiology
No…the folks in the Kinesiology Department are not experimenting with time travel or paying homage to Jules Vern by attempting to reach 20,000 leagues, but what they are doing is still pretty cool. Meet our newest addition…the BodPod!
The Kinesiology Department recently took ownership of a new air-displacement plethysmography machine, otherwise known as the BodPod. This futuristic looking piece of equipment estimates body composition (i.e. body fat percentage) by measuring body volume. The BodPod will be used extensively within the Exercise Science program curriculum, as well as in student-faculty collaborative research. Dr. Maureen Dunn, Professor of Kinesiology and Program Director for Exercise Science believes that having this type of technology at Hope and in the Exercise Science program gives our students “an advantage when it comes to understanding body composition testing and accuracy.”
…having this type of technology at Hope and in the Exercise Science program gives our students “an advantage when it comes to understanding body composition testing and accuracy.”
Common techniques in body composition assessment include skin fold and girth measurements, body density assessment, body mass index, bioelectrical impedance and determination of body volume. Options for volume measurements include hydrostatic/underwater weighing, which measures water displacement (Archimedes Principle), and as the BodPod’s technical name suggests, by using technology that measures air displacement. According to Dr. Brian Rider, assistant professor of kinesiology, “Hydrostatic (or underwater) weighing has been considered the gold standard for many years but it comes with some testing difficulties related to equipment and subject responsibilities. Having space for a large tank to allow for whole body submersion and dealing with individual subject’s fear of water or inability to completely exhale while submerged, make use of this measurement technique challenging.” The BodPod, however, has been proven to be an accurate way to determine body volume without some of the hassles associated with underwater weighing.
The BodPod, however, has been proven to be an accurate way to determine body volume without some of the hassles associated with underwater weighing.
While plethysmography, the third word of the BodPod’s scientific name, is something you might hear at the next Scripps National Spelling Bee, the first two help us understand how the device measures body volume. Air displacement and subsequently body volume is determined by having the subject sit comfortably inside the BodPod which consists of two chambers (test and reference) that share a common wall. The test chamber (where the subject sits), and the reference chamber of the BodPod, both contain a known volume of air when empty. During testing, the subject is asked to breath normally so that the lung volume can be accounted for and thus an accurate body volume determined. By sitting still and breathing in the test chamber, the subject displaces air that is measured via a diaphragm mounted in the common wall. This diaphragm oscillates during testing, leading to subtle changes in air volume within each chamber allowing strategically placed pressure sensors to precisely determine the actual volume of the person sitting in the test chamber. Using this information, body density is calculated and body composition can be determined.
So, next time you happen by the Exercise Science Laboratory and see students and faculty in and around the BodPod, don’t be alarmed… they’re not going to a galaxy far, far away. They are just taking advantage of the latest technology as part of their education and research. Just routine stuff here at Hope.