The human species is an extremely interesting species that can dominate not only its environment but also its own body, thanks to its high-level cognitive functions. Accordingly, people who have experienced (knowingly or unknowingly) the dynamics of muscle biology have realized that they can develop the 650 or so skeletal muscles in their bodies by forcing them in various ways. Thus, physical activities such as exercise and bodybuilding emerged.

When a person wants to move one of his voluntary muscles, that is, one of the muscles that he can control at his own will, a signal from his brain reaches those muscles almost instantaneously and causes the muscle to contract thanks to the chemicals it spreads to the muscles. You can learn the details of this process in our article here. In this article, we will examine how muscles develop as a result of this contraction and its evolutionary significance.

The Evolutionary Meaning of Building Muscle

The muscles that people develop as a result of exercise or muscle work correspond to a type of biological change known as a modification. That is, muscles develop under physical stress, but if this activity is stopped long enough, the muscles will also return to their natural state determined by genes (or converge to it over time). No point in this change is genetic; In other words, the child of someone who builds muscle is not born more muscular.

Therefore, modifications such as muscle building cannot directly contribute to the course of evolution; but of course, being fit in the wild can have indirect advantages. Similarly, if the opposite sex chooses mates based on the amount of muscle, being muscular can have a reproductive success-enhancing effect. This alone cannot produce evolutionary change; However, since the amount of muscle people can develop is determined by the genes they inherit from their parents, if there is a serious sexual selection pressure to be muscular, individuals with a genetic background are more susceptible to muscle growth will breed more easily, and accordingly more prone to muscle development will be born.


What happens here is not that people who build muscles transfer their muscles to the next generation, but that those with the genetic background to produce larger muscles compared to the average of the species gain an advantage in selection by producing these muscles. However, there is no evidence in human history to suggest that large muscles were sexually advantageous and selected over long periods of time. The use of muscles as a sexual signal is a human behavior that began relatively recently. Therefore, it is difficult to say that there is a significant selection pressure on our genes related to muscle production.

Still, every human being can build enough muscle to make it possible for him to survive, as long as he doesn’t have a genetic disease. The level of development that these muscles will reach without any additional exercise, just during the daily work, is well below the upper limit defined by the genes of that individual. This makes sense; for the limit regarding the upper limit of the muscles is rather vague: they will be eliminated by natural selection (due to death) if and only if they develop to such a degree that the individual’s movement is limited. However, if there is not enough environmental pressure for such abnormally large muscles to emerge (which was not even in the wild conditions of our ancestors), there would be no justification for the upper limit at which muscles can develop to be close to a normal amount of development. In other words, the maximum muscle development will be far beyond the muscles of a normal individual. If there were selection pressure, then normal muscle and maximum muscle development would follow each other more closely.

Therefore, by following the correct exercise and nutrition rules, people can go far beyond the level of muscle they would otherwise have. For this reason, an individual who will develop a body should first determine his own limits and choose what kind of body he will have. After that, plans are made according to this goal. You can get more information about this here.

How Do Our Muscles Develop? How Are New Muscles Formed?

This is a question that has puzzled scientists for a long time, and frankly, there is still no clear answer. However, the hypotheses we have to give us very strong possibilities, mainly thanks to the advances in imaging techniques. Therefore, we are able to provide clearer answers on how muscles are produced every day.

Temporary “Swelling” of Muscles After Training

First of all, how do our existing muscles develop? The answer to this question is not very difficult. Because, as you can learn the details from our article here, our muscles consist of muscle fibers and we can think of them as simple cellular structures.


Muscles have two basic types of contraction: isometric contraction and isotonic contraction. For example, let’s say you are trying to lift a mass of 40 kilograms. At the beginning of the lift, your muscles contract until you displace the mass; but no displacement. The contraction in this process is called an isometric contraction. Then, when we give it enough force, the mass starts to move and our muscles contract, applying the same force (or increasing force). We call this isotonic contraction.

The constant repetition of this process, that is, the constant stimulation of certain muscles, results in a constant accumulation of nutrients and protein in these muscles. For this reason, the cells here will develop more and increase in volume. This is how our existing muscles develop. That’s why when you go to a gym and work out for about 2 hours, your muscles feel “swelling”. This bloating is a feeling caused by the continuous stimulation of your muscle cells, resulting in an increase in volume and does not have meaningful persistence. In fact, it is thought that oedema-induced muscle swelling may be the main cause of muscle enlargement in the earliest period (in the first 1–3 weeks of the start of exercise) and therefore may not be a true muscle enlargement. This enlargement does not have a linear relationship with the muscle mass you will eventually acquire and cannot be used to predict the future.

Therefore, much more training will be required for this feeling to become permanent and translate into meaningful muscle growth. In the following article, we will examine the causes and mechanisms of this.

This article is an excerpt from by Karl Liebermann | Jun, 2022 | Medium