Corpulence index

The Corpulence measure (not to be confused with corpulence index, which is measured by actual weight/desired weight) or Ponderal Index (PI) is a measure of leanness (corpulence) of a person^[1] calculated as a relationship between mass and height.^[2] It was first proposed in 1921 as the "Corpulence measure" by Rohrer and hence also known as Rohrer's Index.^[3] It is similar to the body mass index, but the mass is normalized with the third power of body height rather than the second power.^[4]

$\mathrm{CI} = \frac{mass}{height^3}$

For a baby, it is calculated as

$\mathrm{CI} = \frac{birth weight}{Crown-heel-length^3}$^[5]

with $mass$ in kg (kilograms) and $height$ in m (meters), giving a measure with the same dimensions as density. The corpulence index yields valid results even for very short and very tall persons.^[6] Because of this property, it is most commonly used in pediatrics.^[7][8] The normal values for infants are about twice as high as for adults, which is the result of their relatively short legs. It does not need to be adjusted for age after adolescence.^[4] It has also been shown to have a lower false positive rate in athletes.^[9]

The corpulence index is variously defined (the first definition should be preferred due to the use of SI-units kg and m) as follows:

Formula	Units for mass (body weight)	Units for height (or length)	Values corresponding to "normal" BMI in a 180 cm tall person
$\text{CI}=\frac{mass}{height^3}$[8]	kilograms	metres	10.3 to 13.9, 24 for 12-month-old infant[7] ~12 for those 12-year-old or older.[4]
${\displaystyle {\text{CI}}=1000{\frac {mass}{height^{3}}}}$[7]	grams	centimetres	2.4 for 12-month-old infant
$\text{CI}=1000\times\frac{\sqrt[3]{mass}}{height}$[2]	kilograms	centimetres	21.75 to 24.0[10]
$\text{CI}=100\times\frac{\sqrt[3]{mass}}{height}$[11]	kilograms	centimetres	2.175 to 2.4
$\text{CI}=\frac{height}{\sqrt[3]{mass}}$[1]	pounds	inches	12.49 to 13.92

Significance

• It plays a role in assessing whether the intrauterine growth restriction of a child is symmetrical or asymmetrical.^[12]
• CI has been shown to have higher sensitivity, specificity, positive predictive value, and negative predictive value than BMI.^[4]
• Body adiposity index

See also

• Body mass index
• Waist-to-height ratio

References

1. Foods and Nutrition Encyclopedia, Audrey H. Ensminger, Marion Eugene Ensminger. p. 1645
2. EXSS 323: LAB 1 - BIOMECHANICS TOOLS: Computers, Algebra and Trig Oregon State University
3. http://www.wisegeek.com/what-is-the-ponderal-index.htm
4. Babar, Sultan (March 2015). "Evaluating the Performance of 4 Indices in Determining Adiposity". Clinical Journal of Sports Medicine. Lippincott Williams & Wilkins). 25 (2): 183. Retrieved August 2015. Check date values in: |access-date= (help)
5. Fayyaz, Jabeen (June 2005). "Ponderal Index". Journal of Pakistan Medical Association.
6. Lawrence F. Ditmier: New Developments in Obesity Research. Nova Science Publishers, Hauppauge, New York 2006, ISBN 1-60021-296-4
7. Davies, D. P. (1980). "Size at birth and growth in the first year of life of babies who are overweight and underweight at birth". Proceedings of the Nutrition Society. 39 (1): 25–33. doi:10.1079/PNS19800005. PMID 6988835.
8. ACC/SCN NUTRITION POLICY PAPER No. 19 - Glossary by Lindsay H. Allen and Stuart R. Gillespie
9. Babar, Sultan (March 2016). "The Use of Adiposity Indices for Wide Receivers From 2015 NFL Combine". Clinical Journal of Sports Medicine. Lippincott Williams & Wilkins) 2. 26 (2): e23. Retrieved April 2016. Check date values in: |access-date= (help)
10. The source quoted (Oregon State University) states that typical healthy PI values range between 20 and 25.
11. Medical Dictionary University of Newcastle upon Tyne
12. Khoury, MJ; Berg, CJ; Calle, EE (September 1990). "The ponderal index in term newborn siblings.". American Journal of Epidemiology. 132 (3): 576–83. PMID 2389761.

External links

• Online Ponderal Index Calculator, which uses the first definition.
• Ponderal Index Calculator, which uses metric values. (German site)
• Android App for Corpulence Index
• Apple app for Corpulence Index