Is there a 'ceiling' to natural bodybuilding?

Is there an unbreakable ceiling to muscle growth for natural bodybuilders? In other words, can we maintain an overall state of muscle protein synthesis exceeding breakdown for a long time.

To answer this question, we must first clarify what factors affect muscle protein balance.

Muscle protein balance refers to the equilibrium state between muscle protein synthesis and breakdown. If synthesis exceeds breakdown, we can consider muscle protein to be accumulating (i.e. muscle growth); On the contrary, if muscle breakdown exceeds synthesis, it is considered that muscle protein is being lost (i.e. muscle loss); Finally, the synthesis and decomposition levels are equal and cancel each other out, resulting in neither an increase nor a decrease in muscle protein, which is a relatively balanced state.

Many factors can have a positive impact on muscle protein synthesis, such as resistance training, a high protein diet (with energy surplus), and reasonable hormone levels. All of these factors ultimately need to be transformed into signals that cells can recognize and affect gene transcription and translation, and the level of transcription (proteins synthesized according to a certain template) is the key to measuring the final increase in protein.

To what extent can resistance training affect protein translation? In the early stages of resistance training, an increase in muscle protein synthesis rate may indicate adaptation of structural components (i.e., the muscle membrane system); Long term and repeated resistance training may lead to more translation directed towards the synthesis of contractile muscle proteins (i.e. myofibrils).

However, after the myofibrils have grown to a certain extent, they may experience the next plateau period. Before delving deeper into the discussion, we need to first introduce the hypothesis of "muscle nucleus domain", which suggests that although skeletal muscle is a type of multinucleated cell (different from other cells in the body), the number of muscle fibers that each muscle nucleus can support is limited (muscle fibers require genetic material provided by the nucleus as a template to synthesize new muscle proteins). Assuming that a muscle nucleus can only support a certain number of muscle fibers, muscle fibers beyond this range cannot be formed due to the lack of genetic material support. The hypothesis of the muscle nucleus domain is not a wild imagination. There is a lot of evidence that indirectly proves the rationality of the muscle nucleus domain hypothesis. For example, experiments have found that under a given number of muscle nuclei, muscle hypertrophy can only reach a specific range.

During certain stages of life, such as adolescence or periods of concentrated resistance training, the number of muscle nuclei can be supplemented by the fusion of satellite cells. In other words, during these special periods, the number of nuclei in muscles can increase to a certain extent. As age increases, the reserve of basal satellite cells will gradually be depleted or even exhausted. If we represent the number of muscle nuclei in a curve, it should be an inverted U-shaped curve that peaks around the age of 25 and then decreases with age. If a person stays in bed for a long time due to illness, injury, or other reasons, the muscle nuclei in the skeletal muscles will shrink and their numbers will decrease. Aging, neuropathy, metabolic disorders, etc. can also induce disuse atrophy of muscles (characterized by reduced muscle volume and decreased function). It can be seen that there is a close correlation between the number of muscle nuclei and the growth of muscle fibers.

Although there are significant individual differences in the number of muscle nuclei among different individuals, for a specific individual, the potential for Ta to obtain muscle nucleus numbers under natural conditions is also determined because its genetic makeup has been identified. Within this potential range, individuals can optimize muscle protein synthesis and minimize the impact of muscle breakdown through resistance training, proper nutrition, and the use of dietary supplements. However, in terms of the number of muscle nuclei, a potential indicator predetermined by genes, this is actually an unattainable ceiling.

Fortunately, the vast majority of trainers in the world will not touch this ceiling (even if they can get close), but potential is more easily stimulated at specific stages of life, and most people may miss it for various reasons. To realize one's full potential for growth, one not only needs to awaken oneself early on, but also has parents (or teachers, coaches, etc.) who can discover and guide this potential. Of course, training, nutrition, and other conditions are indispensable. This is not a game of words, but rather, a person who truly has potential and can fully unleash it requires many conditions to be met simultaneously, which is also a very difficult event to happen in terms of probability.