Just as no two men are built alike, no two ideal training routines are alike. Different people benefit from different types of training. Using body type to narrow down the most beneficial movements is a good way to make the most of your particular body type, and make the most bodybuilding progress.
There are three kinds of body types. The first, mesomorph, is what you typically see on the professional bodybuilding stage. People with mesomorphic characteristics, or mesomorphs, have a solid muscle structure, are naturally strong, have thick muscle bellies, pleasing join tie-ins, and a long torso. Simple put, they look like bodybuilders. The second type is ectomorph. Ectomorphs often look like basketball players – they have long arms and legs, short torsos, narrow shoulders, and carry low body fat levels. The third type is endomorphic. Endomorphs are the stereotypical "fat kid" look – wide hips, short arms and legs, and tend to carry high levels of body fat. Intelligent bodybuilders realize that individuals with different body structures will benefit from differenting training routines.
Since adding piles of muscle tend to come easier to mesomorphs, they should concentrate upon movements which add quality or finish to their physiques. A base of compound movements is necessary, of course, but the rate at which they grow dictates the need to shape the muscles to maintain the best aesthetic look. For bodybuilding judges, an asymmetrical mesomorph is very hard on the eyes.
Since the primary goal of the skinny ectomorph is to gain weight, training should include mostly compound power movements. Squats, bench press, deadlifts, and rows stimulate overall growth in a way that isolation movements do not. Heavy weights and low reps should be used, and sets should be limited to 12 to 16 per workout. Ectomorphs tend to overtrain. Cardio should be kept to a minimum, as ecotmorphs already tend to be too active to gain muscle.
Typically, endomorphs are able to add muscle fairly easily. However, body fat is easily gained as well. High rep training – in the 12 to 20 range – is most effective for endomorphs. Cardio should be done routinely to keep body fat levels in check.
Ascertaining your own body type might be hard on the ego. After all, everyone wants to be a mesomorph. However, an honest analysis of the strengths and weaknesses of your physique will allow you to customize training based upon body type to make the best bodybuilding gains possible.