Ectomorphe mésomorphique

The mesomorphic ectomorph is the type most often associated with elite endurance running. Long, thin, light, with just enough musculoskeletal robustness to generate force, and very low subcutaneous fat. Skinfolds are minimal.

Nilote populations in East Africa — studied for decades as some of the most uniformly ectomorphic people on earth — fall into this type, as do most elite marathon runners, high jumpers, and male tennis players. The body is built for distance, reach, and economy of movement.

Where the balanced ectomorph is delicate and light, the mesomorphic ectomorph retains visible muscle on a linear frame. They are not bodybuilders, but they are not frail — they can sprint, jump, and absorb training load.

Most teenage boys early in maturation pass through this type before they fill out. For some, it is the adult body; for many, it is a few years before mesomorphy increases.