As calipers only directly assess subcutaneous fat at a few sites, the location and magnitude about other regions’ subcutaneous fat volume and visceral fat volume (fat around the organs) are based on educated conjecture. This may be in part due to assumptions made about the nature and distribution of fat. In fact, even when performed perfectly, calipers can have error rates at the individual level as high as 10-15%. Thus, an equation derived using an error-prone method as a ‘ground truth’ will further compound that error. If you recall from the volumetric methods segment, dunk tanks can have individual error rates exceeding 5%. The most common equation, the Jackson-Pollock Equation (no relation to the painter!), was developed using hydrostatic weighing (dunk tank) as the ground truth. There are a number of different equations that have been derived to transform caliper measurements to body density. A skilled tester makes a world of difference! Even amongst the most practiced professionals, however, other factors such as sweat or body lotion may skew results.Īnother major source of error with this technique comes from the equations used to predict body density from the skinfold measurements. Tester error is, in fact, the largest source of variability in skinfold measurements.
#Caliper body fat skin#
Although the concept itself is rather simple, it takes a fair amount of experience and skill to separate skin and subcutaneous fat from the underlying muscle. More so than the other techniques we’ve discussed, this technique’s accuracy is highly dependent on the skill of the administrator. While the logic behind calipers seems relatively simple, and the equations are derived based on sound logic, like all the methods we’ve discussed, there are a number of possible sources of error. Then, in similar fashion to the volumetric methods, the formula-derived density is plugged into yet another formula along with total body mass (like the Siri Equation) to estimate body fat.
The thickness of the skinfolds at those pre-determined locations (usually 3-7 sites across the body) are combined and plugged into a formula along with age to determine body density. Body fat measurement by way of skinfolds involves using a device, called a caliper, to pinch the skin and underlying fat tissue at a number of pre-determined body points and separate that skin and fat tissue from the muscle underneath.
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