Most of us who have been involved in the bodybuilding game have heard certain exercises referred to as “shaping” or “mass building”. Sometimes the designations are even more specific, referring to exercises as being for “definition” or for “muscle separation.” All of these designations are misguided.
When a muscle contracts, it only contracts one way. It shortens, which then brings that muscle’s origin and insertion closer together, thereby causing the joint (articulation) in between to either bend or extend (or rotate, etc.). There is no such thing as a type of muscle contraction that changes the shape of a muscle – beyond simply growing. There is also no such thing as a type of muscle contraction that causes that muscle’s definition to become enhanced.
When muscles are clearly defined, it is a result of low body fat. The less body fat there is covering our muscles, the more muscle fibers are visible. The accumulation of body fat, and the reduction of body fat, are both systemic processes. That means that we either gain body fat, or lose body fat, systemically – throughout our entire body. Neither gaining nor losing fat, happens only in one area – the arms, for example. That is the myth of “spot reduction”. We cannot selectively lose body fat from our arms, by doing arm exercises.
When a muscle contracts, it either contracts forcefully, or more gently. Forceful muscle contractions, performed on a regular basis (when we workout, for example), will cause a muscle to grow. A gentle muscle contraction will not. Picking up a cup of coffee would be considered a gentle muscle contraction. If the Biceps muscle of your arm did not contract at all, the coffee cup would not get picked up. But if you used the same force of muscle contraction when picking up the coffee cup, as you do when you curl a 40 pound dumbbell, you would smash your face with the cup. So, you use a gentle contraction instead. You are successful in gently bringing the cup to your lips, but the Biceps is not taxed enough to cause growth.
High intensity is what causes a muscle to grow. There are several ways for us to achieve enough “intensity” to cause muscle growth. We can use heavy weight (i.e., “overload”, leading to myofibril growth) or we can use high reps (i.e., “time under tension”, leading to sarcoplasmic growth) – or we can use a combination of techniques that involve both of these. But that is all we can do. It’s like a dimmer switch – increase intensity or decrease intensity.
So, we can either cause a muscle to grow a little, or a lot, or not at all – by adjusting the intensity. But we cannot cause a muscle to improve its definition nor its “muscle separation” (the lines of distinction between individual muscles). Those things are determined by one’s level of body fat and genetics.
I was recently asked whether a Cable Squat (which I was demonstrating by way of video on my Facebook page), was a “mass building exercise” or a “shaping exercise.” Let’s analyze this. When we extend our knees – whether by doing a regular Barbell Squat, or a Leg Extension, or Leg Press – our Quadriceps contract. Quadriceps contraction causes an upward pull on the Patella tendon, which is attached to the front of the Tibia, thereby causing our legs to straighten from a bent knee position. How many ways do you suppose that upward pull on the Patella tendon can occur? One.
Let’s compare this to a “Tug-of-War”. If you’re pulling on a rope, which is being pulled in the opposite direction by another person, how many different ways can you pull on that rope? Of course, you can increase or decrease your intensity. But it’s impossible to pull on that rope in a way that could cause ANY other effect, aside from moving the rope toward you. The same is true with muscle contraction.
When our Quadriceps contract, thereby extending forward a Tibia that has been loaded with an opposing resistance (whether from a Leg Extension machine or a weighted Squat), the only thing the Quadriceps “knows” is that it must generate X amount of force in order to cause that knee extension to happen. If the force required is significant, or if the fatigue is sufficient, it will result in a certain amount of Quadriceps growth.
What kind of signal could the Quadriceps possibly receive from an exercise, that might cause its visible adaptation to be anything other than growth? It’s simply impossible, and illogical, for a muscle to “sense” anything other than LOAD (and fatigue), and for it to adapt in any other way other than hypertrophy (and endurance / power).
Hypertrophy allows a muscle to better handle the need to contract against resistance, in future episodes that are similar. A thicker, stronger muscle can better handle a load, and sustain fatigue. But what purpose or function could increased definition of a muscle have? None. There is no functional advantage, from the standpoint of adaptation, in a muscle being more defined. So there’s no way that an exercise can “cause” that to happen. Definition only happens when the body is forced to use its body fat stores (fuel reserves), because its been deprived of an alternative fuel supply (food / calories eaten).
So, the only possible visible change that can occur in a muscle, with ANY exercise, is growth. No exercise can cause a change of shape of a muscle, an improvement of definition, or an enhancement of muscle separation. Functionally speaking, certain types of intensity can also cause an increase in power and/or endurance. These adaptations can occur simultaneous to muscle growth, of course. But these are not visible.
We’ve been lead to believe – by predecessors who may have been sincere in their belief, but mistaken just the same – that exercises with which we can use heavy weight (i.e., “compound lifts”) are the “mass builders”, and exercises with which we cannot use a heavy weight, are the “shapers.” But this is not accurate. It’s a “belief” that has been passed down through the generations, but few have scrutinized.
There are a number of mechanical factors that determine how much weight can be moved in certain exercises. For example, when an arm is straight, it acts as a longer lever than when an arm is bent. Longer levers magnify resistance more, so less weight can be used. But a muscle does not “know” whether it’s moving 10 pounds with a long lever (straight arm), or 20 pounds with a lever that is half as long (a bent arm). Either way, it translates as “the same resistance” to the working muscle – and prompts the same adaptation.
When an exercise involves more than one muscle (as in a “compound” exercise), a heavier weight can be lifted. But that does not mean that each muscle contributing in that lift, is working harder than if it were working alone during an isolated exercise. A muscle ONLY “knows” how hard it’s working. It does not “know” (nor does it “care”) whether any other muscle is assisting. It only knows whether or not it’s working hard enough to grow, nor not.
If a muscle is loaded enough to prohibit a person from achieving more than ten repetitions (i.e., “heavy weight”), it is causing enough stimulation for myofibril growth. If a muscle is experiencing great fatigue from a set that is lasting longer than 45 seconds (up to about 90 seconds), it is causing enough stimulation for sarcoplasmic growth (and also some degree of myofibril growth). If not, then the muscle is growing very little, or not at all. Either way, no exercise will cause a change in a muscle’s genetically determined shape, and no exercise (by itself) will change a muscle’s definition or separation.
About the Author
Doug Brignole is a veteran competitive bodybuilder, currently in his 38th year of competition, still competing at age 55. Having started at the age of 16, and winning numerous teenage competitions in addition to the Overall Mr. California, and his weight division in Mr. America and Mr. Universe, Doug now has his sights set the World Championship of 2014. He has been an enthusiastic student of biomechanics for many years, writes for a number of websites and magazines, and is now working on his second book. He has been certified by the American College of Sports Medicine and the American Council on Exercise.