The Bod Pod

– MAY 9, 2014

Joint Base San Antonio-Randolph’s Health and Wellness Center offers a variety of classes to help Department of Defense beneficiaries meet their fitness goals.

The HAWC also houses a special piece of equipment that allows its users to measure the progress they’re making toward achieving those goals – especially if they’re trying to lose weight.

Karl Leonard, exercise physiologist, Health & Wellness Center measures the lean body mass percentage of Master Sgt. Bartholomew Vasquez on the Bod Pod April 15, 2014 at Joint Base San Antonio-Randolph. (U.S. Air Force photo by Joel Martinez)

An egg-shaped chamber that measures the body mass, or weight, and volume of the person sitting inside it, the Bod Pod is similar in principle to underwater weighing, Shae Peters, HAWC Health Promotions Program coordinator, said.

“Body density can then be calculated using the formula ‘density equals mass over volume,'” she said. “Once the overall density of the body is determined, the relative proportions of body fat and lean body mass are calculated.”

Peters said the body mass index is a measure of body fat based on height and weight that applies to adult men and women.

The Bod Pod differs from underwater weighing “in that it uses air instead of water to measure body volume, based on the physical relationship between pressure and volume,” she said.

“During a measurement, the Bod Pod produces very small volume changes inside the chamber and measures the pressure response to these small volume changes,” Peters said. “To accomplish this, the interior volume of the empty Bod Pod is first determined, then the volume when the subject is seated inside the Bod Pod is also determined. By subtraction, the subject’s volume is obtained.”

Bod Pod assessments are done by appointment on Mondays from 8:15-11:15 a.m. at the HAWC, she said. Any DOD beneficiary age 18 and older can come in for testing.

There are several rules Bod Pod users must follow, Peters said. Clothing requirements are especially important “as deviations will most likely invalidate test results.”

Men and women should wear a form-fitting spandex-type swimsuit or single-layer compression shorts without padding; in addition, women should wear a jog bra without ruffles, bows or décolletage. A swim cap is used to compress the hair on the head.

Bod Pod users should also refrain from food, water, and exercise for at least two hours prior to testing and should be dry, relaxed and at a normal body temperature.

The Bod Pod is an important fitness tool because it provides “an important baseline measurement to help you gauge individual improvement,” Peters said.

“Weight management depends on the energy balance equation – the amount of energy you put into your body, which is your caloric intake, versus the amount of energy you expend, which is called total energy expenditure,” she said.

“The way to lose body fat is to maintain a negative energy balance. This is done by reducing caloric intake, increasing TEE or a combination of both.”

Resting metabolic rate is also an important measurement, Peters said.

“Your resting metabolic rate is primarily dependent on the fat-free part of your body and accounts for the vast majority of your total energy expenditure,” she said.

By Robert Goetz, www.jbsa.af.mil
Joint Base San Antonio-Randolph Public Affairs