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Somatotypes: What Are They?

Avatar for Hadyn Luke Hadyn Luke posted this on Tuesday 3rd of September 2013 Hadyn Luke 03/09/2013

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Somatotypes: What Are They?

Our blog this week investigates the different kinds of body types and the relevance of each somatotype to the individual.


Every personal trainer will have clients with a range of different body shapes, known as somatotypes. The theory was originally developed in the 1940s by a psychologist called William Sheldon. He began by photographing 4,000 college students from the front, back and side and found that three body types stood out, which he named:

  1. Ectomorph
  2. Mesomorph
  3. Endomorph

The names are based on the outer, middle and inner layers of body tissue (ectoderm, mesoderm and endoderm).

To further categorise body type, Sheldon devised a scale of one to seven to represent how far each individual fitted into each classification. With seven as “very high” and one as “very low”, people are then classed with three numbers, each representing how close they are to each of the body types.

The first number represents endomorphy, the second number mesomorphy and the third number ectomorphy. So, as examples, an extreme endomorph would be represented by 7-1-1 and someone balanced between all three types would be classed as 4-4-4.


Ectomorphs are said to have long, thin muscles and limbs with low body fat and muscle size.

Mesomorphs are more solid and muscular, with a larger frame than ectomorphs, wide shoulders and a narrow waist. They are likely to find it easier to build muscle and are considered more athletic.

Endomorphs have a large bone structure and are more likely to have a larger weight measurement than the other two somatotypes; they are generally predisposed to store fat.

Sheldon also believed that these somatotypes caused people in each group to develop certain characteristics. Although many have discredited this view, there have been some later studies supporting it. What’s more certain is that people often perceive certain body shapes as representing personality types: the jolly fat person, the introverted thin person or the adventurous athletic person.


Each somatotype can alter their muscle mass and adipose tissue using diet and exercise, but their basic bone structure will remain fixed.

A personal trainer should be aware of these different physiques and not adhere to cultural stereotypes. For example, if a new client is an endomorph, it shouldn’t be presumed that they have a bad diet or eat too much and never exercise; they may have good cardio-vascular fitness and blood pressure but their body type prevents them from appearing slender.

Mesomorphs may naturally look fit with good muscle tone even if they rarely train and don’t follow a healthy diet. Equally, ectomorphs may work hard at resistance training, but they will always remain a naturally slim build.


Fitness professionals should set realistic goals for their clients based on their body type and manage their expectations accordingly.

If a client is feeling unmotivated because they are struggling to lose or gain weight or change their body shape, a personal trainer should accentuate the positives: for example, they may look overweight but have good general all-round health, good muscle tone and low blood pressure and resting heart rate.

Different somatotypes will suit different types of exercise. For tall, slim ectomorphs it tends to be activities such as long-distance cardio-vascular training: running and cycling. Endomorphs suit power lifting and exercises that focus on strength training, while mesomorphs are more general all-rounders. The instructor should therefore bear this in mind when setting an exercise programme for different clients.

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