An ectomorph is also called as a hard gainer in gym parlance. You would have heard when people say that they are not able to gain size and strength. The typical ectomorph is a person who exhibits low levels of strength and size prior to physical training. They are usually tall and thin, with relatively low levels of body fat and small, narrow bones. The smaller bone structure is often a shortcoming in strength and power sports. However, they tend to excel in endurance activities, for they exhibit higher proportion of slow twitch muscle fibers. Their fast metabolism also makes it difficult to gain weight. Sheldon classified ectomorphs as being introverted, socially anxious individuals who tend to excel at mental tasks.
However, if a person is very lean he cannot be termed as an ectomorph. What if he is falling to eat enough calories to support muscle growth? Of course, ectomorphs have small bony structures, but their predominant muscle fiber type and hormonal factors also come into play. So we cannot blurt that someone is an ectomorph simply because he has long limbs. Moreover, those hard gainers won’t think that they are the same old ectomorphs about 10 years after graduation. They might typically look like an endomorph: the metamorphosis of a skinny guy to a fat slob.
Ectomorphs generally are over trainers and under eaters. When you are cursed with a Ferrari like metabolism you simply need to consume ample amount of calories. You also need to strength train with greater intensity, less frequency, and much more dedication than the average lifter. It is definitely possible to overcome your genetic idiosyncrasies.
PS: Slow twitch muscle fibers also called as type 1 are predominantly in endurance activities and don’t hypertrophy to a great extent. Fast twitch muscle fibers also termed as type 11 are suited for short burst activity as in sprinting and powerlifting and they hypertrophy to a great extent.