The right and only way to grow

Progressive loads on core exercises!

By Dr. Marco Martone

" first part

Notions of neuro-electrophysiology

Like all organs, muscles are also made up of cells that are specifically called muscle fibers. These cells, inside each muscle of the body, are collected in various groups formed by a very variable number of fibers. Each group, then, is under the control of a single motor neuron; the groups of fibers thus assembled are named of motor units.
The individual fibers of a motor unit are randomly distributed within a small cross section of the muscle. In a section, with a diameter ranging from 5 to 10 millimeters, fibers of different motor units are included (around 15-30).

There are, in the same muscle, motor units composed of fast fibers (FF), intermediate fibers (FR) and slow fibers (S).
The former get tired immediately but develop great strength and are those subject to greater hypertrophy, the latter are slow, develop little strength and have very low hypertrophic abilities, but have great resistance over time.
The intermediate FR fibers have, in fact, intermediate characteristics and can change in appearance now approaching the first hour to the third group, thus determining the biomechanical characteristics of the muscle.
The fast fibers correspond to the white (glycolytic) fibers and the slow fibers to the red (oxidative) fibers of the muscle anatomy.

Each muscular movement that the body makes is the final result of the combination of these elements, neuronal and muscular, in very different sequences, which vary according to the speed and intensity of the movement to be made.
The quantity and type of motor units of which the muscle is composed establishes its mechanical characteristics.

A muscle with a predominance of FF type units will be an extremely dynamic and powerful muscle, but with very rapid fatigue and absolutely unable to develop muscle work or tension for prolonged periods.
A muscle where S-fibers prevail, on the other hand, will have a good grip, but will develop little power.
The possibility of the FR fibers to be placed between the S and FF fibers allows the muscles to change characteristics, transforming into more resistant or more powerful muscles depending on the mechanical stress to which they are subjected.
Of course these transformations are slow and take place over the years, thanks to the continuous muscular exercise of a certain function.

Motor neurons differ according to the type of muscle fibers they innervate; the slow S fibers are innervated by smaller motor neurons, while the fast FF fibers are innervated by large motor neurons.
Smaller motor neurons have a lower arousal threshold, which implies that motor units made up of S fibers are recruited first.
This concept, attributed to Henneman, is called Principle of size in the motor unit recruitment process, which occurs, as a rule, with a progression of this type:

S → FR → FF

with the FF fibers activated, therefore, only in some cases, that is when certain levels of force are necessary to overcome the load in question.

Knowing from the muscular physiology that the FF fibers are the most responsible for hypertrophy, it becomes clear that our purpose in the gym is to train hard, trying to recruit and use them in the exercise.
This, however, will happen if and only if the load is such that both the S fibers and the FR are not sufficient to overcome it, thus requiring the help of the powerful and more hypertrophied FF fibers.
Understanding how the training load behaves in the fiber recruitment process and the relationship of the latter with hypertrophy, it becomes clear that your workouts, for the best results, from now on will have to be progressively more intense and , to make this happen, even much shorter as the FF fibers tire very quickly.

Practical application

Now I just have to tell you where to focus your efforts, or rather what exercises you need to perform to get results.
I hope to make it clear with an example why to progress in terms of strength and mass you must perform almost exclusively multi-joint exercises.
Let's look at two shoulder exercises: the slow barbell forward and the side raises.
Since the slow forward with the barbell is a multiarticular exercise, it involves many more muscles (in this case also the triceps) and also makes various accessory muscles work (for example the stabilizing and synergistic ones); the lateral raises, on the other hand, being an exercise in isolation, involve only the lateral head of the deltoid.
It seems clear that with the slow forward you can use much more load, even reaching 100 kilograms and more, while in the lateral lifts (both with the application of cheating and with the help of a training partner) you will hardly reach 16. -18 Kg.
The difference in stress on the delts brought about by these two exercises is therefore obvious. There can be no comparison, not to mention that the multi-joint exercises also have a marked effect on the whole organism, as they shake the hormonal system towards anabolism which does not happen with the use of specific exercises.
Ultimately the core exercises (squats, deadlifts, leg presses for those who have trouble squatting, bench presses, parallel pushups, pull-ups and overhead presses) are the ones that build the substance of the physique. . Isolation exercises, on the other hand, work on muscle details and should only be used after the desired muscle development to perhaps refine some details.
Another data to be taken into consideration to confirm that the use of multi-joint is the best choice is that carrying out a workout with many isolation exercises also means training more time than necessary. Such a card is made up of many more exercises, therefore time to complete it is really too much if you want to grow, as after about 60-70 minutes the anabolic hormones drop dramatically while the catabolic ones like cortisol soar.
I conclude with a reminder: