Corpulence index explained

The Corpulence Index (CI) (also Ponderal Index (PI) or Rohrer's Index) is a measure of corpulence, or of leanness in other variants, of a person^[1] calculated as a relationship between mass and height.^[2] It was first proposed in 1921 as the "Corpulence measure" by Swiss physician Fritz Rohrer^{[3] [4]} and hence is also known as Rohrer's Index.^[5] 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. In 2015, Sultan Babar showed that CI does not need to be adjusted for height after adolescence.^[4]

CI = (mass)/(height ^{3}) with mass in kilograms and height in metres, giving a measure with the same dimensions as density. The corpulence index yields valid results even for very short and very tall persons,^[6] which is a problem with BMI — for example, an ideal body weight for a person 152.4 cm tall (48 kg) will render BMI of 20.7 and CI of 13.6, while for a person 200 cm tall (99 kg), the BMI will be 24.8, very close to the "overweight" threshold of 25, while CI will be 12.4.^[7]

Because of this property, it is most commonly used in pediatrics.^{[8] [9]} (For a baby, one can take crown-heel length for the height.^[10]) 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.^[11] It has also been shown to have a lower false positive rate in athletes.^[12]

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	Values considered normal or typical
		for a 12-month-old infant	beyond infancy
CI = (mass)/(height ^{3})	kg/m^3	24	12
CI = (height)/(\sqrt[ 3 ]{ mass) }^[13]	inch * pound ^-1/3	While this formula appears in some literature, it is not a meaningful corpulence index and should not be used.

Significance

• It plays a role in assessing whether the intrauterine growth restriction of a child is symmetrical or asymmetrical.^[14]
• CI has been shown to have higher sensitivity, specificity, and positive and negative predictive values than body mass index for determining adiposity.
• It is used to calculate ectomorphy in the Heath–Carter formula.^{[15] [16]}

Categories

Adults^[17] !Category!PI (kg/m³)

Underweight	8-11
Normal range	11-15
Overweight	15-17
Obese	>17

For infants, units of grams and centimeters are used instead, then the value is multiplied by 100.PI _{child} = 0 . 1 x PI _{adult} = 100 x \dfrac{ mass _{g} }

Newborn infants and children^[18] !Category!PI (child)

Very low	≤1.12
Low	1.13-1.19
Middle	1.20-1.25
Upper middle	1.26-1.32
High	1.33-1.39
Very high	≥1.40
Healthy range	1.2-1.6

See also

• Body adiposity index
• Body mass index
• Waist-to-height ratio

External links

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

Notes and References

1. Foods and Nutrition Encyclopedia, Audrey H. Ensminger, Marion Eugene Ensminger. p. 1645
2. http://oregonstate.edu/instruct/exss323/Intro_Lab/PI.HTM EXSS 323: LAB 1 - BIOMECHANICS TOOLS: Computers, Algebra and Trig
3. Der Index der Körperfülle als Maß des Ernährungszustandes. F. Rohrer. Münchner Med. WSCHR. 68. 1921. 580–582.
4. Web site: Multidirectional regression analysis. Moortel. Koen Van de.
5. Web site: What is the Ponderal Index? (With pictures). 3 March 2024 .
6. Lawrence F. Ditmier: New Developments in Obesity Research. Nova Science Publishers, Hauppauge, New York 2006,
7. Taller people should have Higher BMI's and Blood Pressure Measurements as their Normal. Biomed J Sci & Tech Res. 2018. 10.26717/BJSTR.2018.06.001381. free. v Roth. Jonathan. 6. 4.
8. 10.1079/PNS19800005 . Size at birth and growth in the first year of life of babies who are overweight and underweight at birth . 1980 . Davies . D. P. . Proceedings of the Nutrition Society . 39 . 25–33 . 6988835 . 1. free .
9. http://www.unsystem.org/scn/archives/npp19/ch06.htm ACC/SCN NUTRITION POLICY PAPER No. 19 - Glossary
10. Fayyaz. Jabeen. Ponderal Index. Journal of Pakistan Medical Association. June 2005. 55. 6. 228–9. 16045088.
11. Evaluating the Performance of 4 Indices in Determining Adiposity. Babar. Sultan. March 2015. Clinical Journal of Sport Medicine. August 31, 2015. Lippincott Williams & Wilkins) . 25. 2. 183.
12. The Use of Adiposity Indices for Wide Receivers From 2015 NFL Combine. Babar. Sultan. March 2016. Clinical Journal of Sport Medicine. April 30, 2016. 26. 2. Lippincott Williams & Wilkins) 2. e23.
13. Web site: Ponderal Index (Corpulence Index) Calculator.
14. Khoury. MJ. Berg. CJ. Calle. EE. The ponderal index in term newborn siblings.. American Journal of Epidemiology. September 1990. 132. 3. 576–83. 2389761. 10.1093/oxfordjournals.aje.a115694.
15. Book: Anthropometrica: A Textbook of Body Measurement for Sports and Health Courses. Kevin . Norton. Tim . Olds. Australian Sports Commission; UNSW Press. 1996. 978-0868402239.
16. Book: Rempel, R. A Modified Somatotype Assessment Methodology. 1994. Simon Fraser University. 978-0-612-06785-1.
17. Mohajan . Devajit . Mohajan . Haradhan Kumar . 2023-06-06 . Ponderal Index: An Important Anthropometric Indicator for Physical Growth . Journal of Innovations in Medical Research . en . 2 . 6 . 15–19 . 10.56397/JIMR/2023.06.03 . 2788-7022.
18. Bannik . Sudip Datta . January 2011 . Evaluation of Health Status of Pre-Menarcheal and Post-Menarcheal Girls by Rohrer Index in Purulia, West Bengal . Journal of Public Health and Epidemiology . 3 . 1 . 13–16 . 2141-2316 . Academic Journals.