Corpulence Index (CI)
- The Corpulence Index (CI) equation consists of three experimental terms.
- Given all but one of the experimental terms, this tool solves for the missing one.
- To use the tool, one of its form fields must be left empty.
- To empty a field, just double click it.
- If no field is left empty, the tool will randomly empty one and recompute its value based on the values of the other fields.
- This tool cross-maps all three experimental terms that define the Corpulence Index (CI), also known as the Ponderal Index (PI) and Rohrer's Ponderal Index.
CI is similar to the Body Mass Index (BMI), but is defined as the body mass divided by the third power of the body height. The index is frequently expressed in SI units of kg/m3, resulting from mass in kilograms and height in meters. So if when using this tool a user input the mass in pounds (lb) and height in inches (in), these will be converted to SI units.
BMI and CI are special cases of a large class of ratios based on scaling of weight for height where the ratio of these two variables is
where x = 2 for BMI and x = 3 for CI.
Notice that dividing a BMI range by height gives a CI range.
- Interpretation of results
CI is an estimate of leanness (corpulence) of a person. This index yields valid results even for very short and very tall persons. Thus, it is most commonly used in pediatrics (Nili, Makipour, & Mobini, 2003).
The normal values for infants are about twice as high as for adults, which is the result of their relatively short legs. The index does not need to be adjusted for age after adolescence, and has a lower false positive rate in athletes than the Body Mass Index (BMI). Because of this, CI is used as an alternative index in sport medicine.
CI has been used in newborns as an indicator of fetal growth status, especially to assess asymmetrical intrauterine growth retardation (Khoury, Berg, & Calle, 1990).
CI is not an absolute measurement of health. The index does not show a difference between people with lots of muscle and lots of fat. It does not differentiates between body types that may hide muscle or fat mass in different parts of their bodies.
- Lab techs as well as physiology or allied health teachers and their students.
- What is the CI and BMI of a 120-pound, 5'3"-tall person?
- Compute a CI range for a 5'10"-tall person with a normal healthy weight.
- Using the healthy ranges of BMI indices, construct a table of equivalent healthy ranges of CIs for adults 1.4 to 2.1 meter tall. Construct the table in 0.1 meter increments.
- Khoury, M., Berg, C. J., & Calle, E. E. (1990) The Ponderal Index in Term of Newborn Siblings. Am J Epidemiol, 132 (3): 576-583.
- Nili, F., Makipour, M., & Mobini, J. (2003). The Value of Ponderal Index as a Prognostic Factor in Predicting Complications in Term Neonates. MJIRI (17) 3, 197-201.
- Wikipedia (2017). Corpulence Index.
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