Corpulence index

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.^[6] In 2015, Sultan Babar showed that CI does not need to be adjusted for height after adolescence.^[4][6]

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

with ${\displaystyle \mathrm {mass} }$ in kilograms and ${\displaystyle \mathrm {height} }$ 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,^[7] 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.^[8]

Because of this property, it is most commonly used in pediatrics.^[9][10] (For a baby, one can take crown-heel length for the height.^[11]) The normal values for infants are about twice as high as for adults, which is the result of their relatively short legs.^{[citation needed]} It does not need to be adjusted for age after adolescence.^[6] 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
${\displaystyle {\text{CI}}={\frac {\mathrm {mass} }{\mathrm {height} ^{3}}}}$[9][10]	kg/m3	24[9]	12[6]
${\displaystyle {\text{CI}}={\frac {\mathrm {height} }{\sqrt[{3}]{\mathrm {mass} }}}}$[1][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.^[6]
• It is used to calculate ectomorphy in the Heath–Carter formula.^[15][16]

Categories

Adults^[17]

Category	PI (kg/m3[a])
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.^[17]

${\displaystyle {\text{PI}}_{\text{child}}=0.1\times {\text{PI}}_{\text{adult}}=100\times {\dfrac {{\text{mass}}_{\text{g}}}{{\text{height}}_{\text{cm}}^{3}}}}$

Newborn infants and children^[17][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
• Body roundness index
• Waist-to-height ratio

Notes

1. Original source writes kg/m² but this is an error.

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. F. Rohrer (1921). "Der Index der Körperfülle als Maß des Ernährungszustandes". Münchner Med. WSCHR. 68: 580–582.
4. Moortel, Koen Van de. "Multidirectional regression analysis".
5. "What is the Ponderal Index? (With pictures)". 3 March 2024.
6. Babar, Sultan (March 2015). "Evaluating the Performance of 4 Indices in Determining Adiposity". Clinical Journal of Sport Medicine. 25 (2). Lippincott Williams & Wilkins): 183. Retrieved August 31, 2015.
7. Lawrence F. Ditmier: New Developments in Obesity Research. Nova Science Publishers, Hauppauge, New York 2006, ISBN 1-60021-296-4^{[page needed]}
8. v Roth, Jonathan (2018). "Taller people should have Higher BMI's and Blood Pressure Measurements as their Normal" (PDF). Biomed J Sci & Tech Res. 6 (4). doi:10.26717/BJSTR.2018.06.001381.
9. 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.
10. ACC/SCN NUTRITION POLICY PAPER No. 19 - Glossary Archived 2007-08-20 at the Wayback Machine by Lindsay H. Allen and Stuart R. Gillespie
11. Fayyaz, Jabeen (June 2005). "Ponderal Index". Journal of Pakistan Medical Association. 55 (6): 228–9. PMID 16045088.
12. Babar, Sultan (March 2016). "The Use of Adiposity Indices for Wide Receivers From 2015 NFL Combine". Clinical Journal of Sport Medicine. 26 (2). Lippincott Williams & Wilkins) 2: e23. Retrieved April 30, 2016.
13. "Ponderal Index (Corpulence Index) Calculator".
14. Khoury, MJ; Berg, CJ; Calle, EE (September 1990). "The ponderal index in term newborn siblings". American Journal of Epidemiology. 132 (3): 576–83. doi:10.1093/oxfordjournals.aje.a115694. PMID 2389761.
15. Norton, Kevin; Olds, Tim (1996). Anthropometrica: A Textbook of Body Measurement for Sports and Health Courses. Australian Sports Commission; UNSW Press. ISBN 978-0868402239.
16. Rempel, R (1994). A Modified Somatotype Assessment Methodology. Simon Fraser University. ISBN 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. 2 (6): 15–19. doi:10.56397/JIMR/2023.06.03. ISSN 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. ISSN 2141-2316 – via Academic Journals.

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