Few men and women are born with the capability to add massive amounts of lean muscle. Unfortunately, this potential is a genetic predisposition.

But before you get frustrated and give up, everyone has the ability to increase strength and size—it’s just that few of us can attain strongman size. Several genetic factors come into play in determining how much muscle you can add to your body.

Body Type

Your body type plays the largest role in determining your size and strength potential. It is primarily defined by your skeletal structure, the width of your hips and shoulders and your body composition (muscle to fat ratio). There are three main body types:

• Ectomorph: Thin and narrow; difficult to add muscle; extremely low body fat percentage (See Pack on the Pounds With the Skinny Guy Workout.)
• Mesomorph: Naturally muscular body with broad shoulders and narrow waist; greatest bodybuilding potential; low body fat percentage
• Endomorph: Physically rounder and more pear-shaped; easy to put on fat, a trait that can hide muscle gains.

Length of the Muscle Belly 

The muscle belly is the thickest part of a muscle, usually midway between the two ends. It’s the part of the muscle most responsible for contracting (think Bicep Curls). It does not include tendons or bones. The longer an individual’s muscle belly, the greater his or her growth potential, since muscle belly is the only part of the muscle that can grow larger.

Lever Length

The body is a system of levers and pulleys. The length of a bone can create a leverage advantage or disadvantage in the weight room, since it determines the amount of weight you can lift. Generally, a longer bone creates a distinct leverage disadvantage in the weight room compared to a shorter one. On the field, however, longer levers can confer a performance advantage. For this reason alone, we should not compare athletes’ strength in the weight room. Each athlete does a different amount of work on each rep, depending on the length of his or her limbs and where each tendon attaches to the bones.

The Insertion Points

This is the spot where muscle attaches to the moving bone. For example, all biceps attach in the same spot, near the shoulder. The difference is where the biceps inserts on the forearm. The farther away from the elbow the biceps inserts, the better leverage you have for performing a Biceps Curl. This same kind of structural advantage or disadvantage exists for the most muscle groups in the body.

Watch the video below for a sneak peek at what you can learn from a SMARTER Team Training clinic.