Mesomorphy

Mesomorphy is a concept in the somatotype system describing a physique that is naturally muscular, with a robust bone structure and relatively low body fat. The term originates from the work of American psychologist William Herbert Sheldon in the 1940s. In Sheldon's framework, body types were grouped into endomorphy (soft and round), mesomorphy (muscular and well-built), and ectomorphy (lean and delicate).

Mesomorphs are typically characterized by broad shoulders, a narrow waist, a deep chest, and an athletic build. They tend to gain muscle mass easily and respond well to resistance training, while often maintaining lower levels of body fat than individuals with endomorphic traits.

Measurement and classification: In modern practice, the Heath-Carter somatotype method assigns a three-number rating for endomorphy, mesomorphy, and ectomorphy. Mesomorphy is estimated from bone breadths (such as humerus and femur) and limb girths, combined with other measurements.

Influences and limitations: The determinant of body type is largely genetic, but training, nutrition, hormones, and age can modify fat distribution and musculature. The somatotype framework is descriptive and not a precise predictor of performance or health.

Contemporary view: While influential in fitness and bodybuilding history, mesomorphy is considered a historical classification rather than a deterministic label. Modern approaches emphasize individual variation and focus on body composition and functional capacity rather than fixed typologies.