The interest in categorizing body type in athletes has a long history that goes back to the ancient Greeks. This interest has led to the development of various systems of describing or classifying the athlete physique. One of these classification systems is somatotyping, which was originally proposed by W.H. Sheldon in his 1940 book, “The Varieties of Human Physique”. Sheldon believed that an individual’s somatotype was fixed due to their genes and even went so far as to suggest that an individual's mental characteristics could be determined by somatotyping. Today, the ability to determine an individual’s mental characteristics using somatotyping has largely been debunked and is no longer utilized. In addition, somatotyping is now considered to be phenotypic rather than just genetic and is therefore amenable to change by factors such as aging, nutrition, exercise, etc. (Carter & Heath 1990). There has been a recent resurgence in the use of somatotyping in not only characterizing the physique of athletes but also in non-athletic individuals. This has led some individuals to try to use somatotyping to determine body composition as well. In this blog post, we will explain further somatotyping as well as discuss what it can and cannot do.

What Is a Somatotype Score?
First, what is somatotyping?  Basically, somatotyping is a system that rates an individual’s physique in three areas: endomorphy, mesomorphy, and ectomorphy. Endomorphy is the relative fatness, mesomorphy is the relative musculoskeletal robustness and ectomorphy is the relative linearity or slenderness of a physique (Norton & Olds, 1996). Each area can be scored, and the three scores are then used to describe an individual’s physique.  For example, someone with a score of 4-6-3 would have a score of four for endomorphy, 6 for mesomorphy and 3 for ectomorphy. The numbers give the magnitude for each of the three categories. A score of 2 to 2½ are considered low, 3 to 5 are moderate, 5½ to 7 are high and scores above 7½ are considered to be very high (Carter & Heath 1990). There is no upper limit for score, but a score above 12 is extremely rare (Norton & Olds, 1996). A pure endomorph would have a score of 7–1–1, a pure mesomorph would have a score 1–7–1 and a pure ectomorph would have a score of 1–1–7. Few individuals are a pure endomorph, mesomorph or ectomorph; most individuals are a composite of all three.

Determining Somatotype Score
There are three ways of obtaining the somatotype score: 1) the photoscopic method in which ratings are made from a photograph; 2) anthropometric method, in which anthropometric measurements are used to estimate the somatotype; and 3) the anthropometric plus photoscopic method, which combines anthropometry and ratings from a photograph. Because of the difficulty with rating photographs, the anthropometric method is the most popular of these three methods. The anthropometric method utilizes 10 anthropometric measurements: individual's weight (kg), height (cm), upper arm circumference (cm), maximal calf circumference (cm), femur breadth (cm), humerus breadth (cm), triceps skinfold (mm), subscapular skinfold (mm), supraspinal skinfold (mm), and medial calf skinfold (mm)(Carter & Heath 1990). After taking these anthropometric measurements somatotype values for endomorph, mesomorph and ectomorph can then be calculated using a rating form (see figure) or a series of mathematical equations.  Either method you use to determine the score will give you the three scores that ultimately make up the somatotype score.

Take Home Message
It is important to recognize that the somatotype score is only a general description of the human physique based upon the three areas: endomorphy, mesomorphy, and ectomorphy. It does not answer important questions regarding composition.  The amount of lean mass and fat mass cannot be determined.  For many sports, it is the amount of lean mass and fat mass and the ratios of these masses in the human body that ultimately affect performance.  Although somatotyping is an interesting way to critique the human physique, athletes still need to look at body composition. Finally, even though the somatotype score can be affected by training it does not really inform an individual on how well their training program is altering their lean and fat masses.

References
Sheldon, WH. (1942). The Varieties of Temperament. New York; London: Harper & Brothers.
Sheldon, WH. (1954). Atlas of Men: A Guide for Somatotyping the Adult Male at All Ages. New York: Harper. 
Carter, JEL, Heath, BH. (1990). Somatotyping-development and Applications. Cambridge University Press.
Norton, K. Olds, T. (1996). Anthropometrica: A Textbook of Body Measurement for Sports and Health Courses. Australian Sports Commission; UNSW Press. 

About the Author
Donald Dengel, Ph.D., is a Professor in the School of Kinesiology at the University of Minnesota and is a co-founder of Dexalytics. He serves as the Director of the Laboratory of Integrative Human Physiology, which provides clinical vascular, metabolic, exercise and body composition testing for researchers across the University of Minnesota.