International Sports Sciences Association (ISSA) Trainer Practice Exam 2026 - Free Trainer Practice Questions and Study Guide

The somatotype system classifies the human body into three primary categories: endomorph, mesomorph, and ectomorph. This classification system, developed by William Sheldon in the 1940s, is used to describe an individual's body composition, physique, and overall body shape based on various characteristics such as fat distribution, muscle mass, and skeletal structure.

Endomorphs typically have a higher percentage of body fat, a wider waist, and a softer body structure. Mesomorphs are characterized by a muscular physique with broad shoulders and a narrower waist, often considered the ideal body type for athletic performance. Ectomorphs are usually lean and tall, with lower body fat and less muscle mass.

This three-category classification allows trainers and fitness professionals to tailor exercise and nutrition programs to an individual's specific body type, optimizing their potential for fitness and health. Recognizing and understanding these classifications can aid in the development of personalized fitness strategies based on how individuals naturally respond to training and diet.