Body shape

Body Shape
One method used to assess body shape, called somatotyping, rates a person's body on three factors: endomorphy (fatness), mesomorphy (muscularity) and ectomorphy (slenderness).

Ectomorph

Thin
flat chest
delicate build
young appearance
tall
lightly muscled
stoop-shouldered
large brain
Has trouble gaining weight.
Muscle growth takes longer.

Ectomorphs have very high metabolic rates. This makes it very difficult for them to gain both muscle and strength. The ectomorph faces a much greater challenge than does the mesomorph in gaining muscle and therefore must be patient with muscle gains when resistance training. Those with this body type should stick to the basic hypertrophy phase of training (in the 8-12 rep max range). Fewer reps means going heavy - a high intensity workout. In turn, a longer rest period in between sets is necessary so you're thoroughly recuperated between sets.

Mesomorph

hard, muscular body
overly mature appearance
rectangular shaped
thick skin
upright posture
gains or loses weight easily
grows muscle quickly.

This is the guy or gal who comes in to the gym and doesn't really look as if he knows what he is doing, nor does he stay very long, yet grows like a weed? Some of these people make enormous progress despite their complete lack of training or nutritional knowledge - imagine what they could do if they did. Mesomorphs can basically get away with doing less and achieving more. However, mesomorphs are also more prone to over training because they see results so quickly. They also tend to do the same routine over and over, again because they see results. This could in fact lead to decreased gains. For this reason it is recommended that mesomorphs change up their routine often. Pyramid training is an ideal method for this body type.

Endomorph

soft body
underdeveloped muscles
round shaped
over-developed digestive system
trouble losing weight
generally gains muscle easily.

Endomorphs are generally those with a large bone structure. They can probably hoist some relatively heavy weights around the gym, but with a slower metabolism, fat loss is very difficult, which can hide their hard-earned muscle gains (or fat loss).
The problem with the three approaches is that most people are a combination of the three types. For example a person with a stocky build who is tall may be a Meso - ecto. So what does our body type mean for a training program? In a nutshell we have to recognize that any training program be tailored for our bodies, and the program that works for one person may not work for someone else.