FACTORS IN FORCE DEVELOPMENT.
3 types of factors will condition the development of strength in a muscle:
nervous factors linked to the way it is brought into play
elastic factors related to its ability to stretch
structural factors related to its morphology
a / nervous factors
Initially, it is the bringing into play of an increasingly large number of muscle fibers that will make it possible to produce an increasing force and gradually increase the strength of the muscle. It is the phenomenon of recruitment .
The sequence of recruitment inside the muscle is always the same :
there is first recruitment of slow fibers, during sub-maximal contractions
then resistant fibers
finally, fast fibers, which are only stimulated during contractions close to the maximum.
Muscular performance is also conditioned by the simultaneity of contraction of motor units : it is the synchronization of responses. Only the training with heavy loads allows the synchronization of the fast MUs.
b / factors linked to stretching : use of the elastic qualities of the muscle.
A pre-stretched muscle has been shown to produce greater force when it contracts. On this principle, we developed a specific form of training : plyometrics. It is a succession, in a very short time, of an eccentric phase and a concentric phase. It makes the best use of the elastic components of the muscle and of the reflexes associated with stretching.
This method occupies an important place in bodybuilding in high level sport, because the explosiveness is the first characteristic of the sporting gesture.
c / factors linked to the morphology of the muscle : hypertrophy.
Muscle building causes the muscle to thicken without revealing new fibers. The increase in the mass of a muscle results only from the hypertrophy of the fibers, that is to say from an increase in their volume by the creation of additional myofibrils. Mechanical stresses on tendons and other muscle-related structures trigger protein synthesis.
The 3 main causes that explain the increase in muscle volume are:
increase in the size of myofibrils (actin and myosin)
thickening of connective tissue
increased vascularity (density of the vessels)
The hypothesis of an increase in the number of fibers (hyperplasia) is no longer retained as a factor of increase in volume.
To hypertrophy a muscle, the phenomenon of overcompensation must be brought into play. This is the basic principle of strength training. It increases the response potential of the organism, in 3 distinct steps:
In a 1 st time: one seeks the maximum or the physical qualities that we want to bring to deplete .
The 2 nd time is that of the resting phase, which will replenish the energy of the body stocks and a return to the original level .
Finally, in a 3 rd time it has been applied, the agency exceeded its initial level: the overcompensation phase.
The point, and the difficulty, of training lies in training at the top of the overcompensation phase.
In conclusion : There is no linear relationship between muscle size and strength developed. A beginner who does weight training increases his strength quickly and the muscle has undergone few changes. The gain in strength, at the beginning, does not come from an adaptation of the muscle fiber, but from an improvement in nerve coordination . There is no change in the intimate structure of the cell.
It is only in a second step, that training (under certain conditions) will allow the increase in mass. Training creates metabolic and structural alterations that contribute to the synthesis of new contractile protein structures within muscle fiber . It is at this stage that food plays a more important role, because this process of muscle reconstruction requires a supply of raw materials, amino acids, which will allow the synthesis of proteins.
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