Every muscle is composed of fibers. The number of fibers varies according to the particular muscle as well as varying from one individual to another for a specific muscle. Muscle fibers of the upper arm of one man may be 40,000 while the calf of the same man may contain as many fibers as 1,120,000. Yet still another person may have only 946,000 fibers in the calf muscle.
Because heredity controls the number of muscle fibers an individual was born with, neither exercise nor anything else can alter it. The number of muscle fibers present in each muscle controls the size to which that muscle can grow. This fact was proven by scientists as far back as 1897. However, the muscle fibers themselves can grow in diameter width. This indicates that any muscle can be developed and/or be increased in size.
Although unlimited size cannot be expected, a far more interesting thing can be obtained and this is in the shaping of the muscle. This aspect of muscular development is almost unlimited, providing you know the proper positional exercise movement to bring out to prominence the particular aspect of the muscle you wish to enlarge or develop. SHAPING a muscle is just as important as working for size or more so.
Initially, to increase muscle size, you must increase the intensity of work done within a given time. This means it doesn't matter how much work you do but hos fast you do it. This is known as the OVERLOAD principle. The most significant experiment proving this involves rats which were trained to run at different speeds for varying lengths of time. The rats that ran at 6 meters per minute for 195 miles had smaller muscular development than those rats that ran 26 meters per minute but for only 58 miles.
This principle of overload explains why sprinters have larger muscle size all over their bodies than long distance runners. Although it is more work to run a mile than 100 yards, the sprinter is doing more work per second and as a result, his muscles will enlarge.
My contention has always been that overwork causes muscle loss due to over-tonis (tissue shrinking), nerve exhaustion and finally excessive male hormone depletion.
One school of thought insists that if you place enough stress on a given muscle (failure principle, Isometrics, Concemetrics), the muscle will develop maximum symmetry. This concept is erroneous as my findings have shown me. If it were true, we would need no diversified equipment such as the preacher bench for low bicep and brachialis antecus development, or bentover barbell curls for high (peak) bicep and coraco brachialis development for instance. Now would we need incline barbell and dumbbell work for high pecs (clavicular aspect of pectoral), or parallel dips and/or decline bench work with weights or pulleys for the low pec.
The long fibers of the lats are developed by overhead work, the belly of the lat by using a 45 degree pulley, and the teres major by pulling straight back to the chest with a pulley 16 inches off the floor from a sitting positionm, etc. Furthermore (failure principle), not enough repetitions and sets do not increase blood circulation enough to raise the pulse rate to where oxygen is demanded by the blood stream. As a result, accelerated growth is not obtained. The cardiovascular and circulatory systems must be activated.
The famous Easton Brothers Gym . . .
. . . which I attended 33 years ago [early 1940's], taught me to work out to total failure and my gains were very slow. Not until I opened my first gym did I begin to make the gains I was after and that was by employing a system of pumping with about 60-80 degrees [percent] of my maximum. I talked to weightlifters and observed that if they pushed themselves too hard in training, they lost their strength for weeks at a time.
Over the years, I constantly got into trouble by over-working due to over-enthusiasm. At that point, I'd become disgusted with my lack of gains and lay off. After about 3 days, I noticed I was growing and I'd become excited and start training again (over-training) and my gains would again come to a standstill. It wasn't until I decided to enter physique competition that I accidentally discovered the highly accelerated system which I found to be the real result producer which I teach now. I discovered it because I couldn't face the long, slow, tedious workouts I believed I had to face every day. Thus, I tried to get my workout over as fast as possible!
Now, for the first time, I began to show real muscularity and gains. The men who judged physique contests at this time were puzzled by so much muscularity. Quotes from physique magazines stated I didn't place higher in whatever contest because of too much muscularity! They thought this kind of cut up physique was slightly repugnant so I lost most muscular titles to smoother men who had the type of definition of that day -- the type the judges were accustomed to accepting. But the attitude of the times has changed.
To sum up what I am trying to explain . . .
choose an exercise that will develop the weakest portion of each of your body parts and do one exercise only, 6 sets of 6 reps to 8 sets of 8 reps and see how fast you can get it done! SPEED in a workout is your best form of progressive resistance for bodybuilding. Use the best isolation type form possible because cheating methods bring in other muscles to assist in performance of the movement and destroys the isolation principle you should be striving for here.
And finally, remember that when taking instruction from anyone, observe his physique and see if he has obtained results from what he's telling you to do. Find out who he takes credit for -- how many physique champions he's turned out.
Enjoy Your Lifting!