Muscle Mathematics

There are some very basic facts about the development of muscles, so simple that we can almost say “muscle mathematics”. We can collect them in 3 main items:

  • Muscle development depends on the balance between muscle breakdown and muscle building. For a muscle to develop, muscle building must be higher than muscle breakdown. This is possible because protein synthesis is higher than protein degradation. So, muscle building is built on protein math somewhere.
  • Both protein synthesis and protein degradation are controlled through the cellular mechanisms associated with these processes. Therefore, it is imperative to understand these cellular mechanisms in order to increase protein synthesis and decrease protein degradation.
  • Resistance exercises (underloading) significantly increase muscle growth. However, permanent muscle growth is a relatively slow and long process; therefore, it is inevitable to work steadily for at least a few months. In contrast, even a single muscle exercise boosts protein synthesis for 2–4 hours after that exercise, and may even take up to 24 hours, according to some studies.
  • The effect of muscle resistance exercises on protein synthesis is much higher than on protein breakdown; therefore, the main source of muscle work causing permanent muscle building is its effect on protein synthesis.


Muscle Biology

At the end of the article, we will summarize what we have learned in the light of muscle development theories, which we will see shortly, and you will find tidy information in terms of muscle biology; however, before we move on to the theories, we find it useful to give some basic information.

Almost all studies show that the muscles of men and women who are under load respond to this load in almost exactly the same way. The difference is due to general differences between the sexes: body size, body composition and hormone levels. As a result of these, men experience a higher muscle enlargement on average. Although the biological limits of muscle enlargement are not known precisely, it is thought that the muscle cross-sectional area can be enlarged by 30–70% naturally.


Changes occur in muscle cells due to ageing. One of them is sarcopenia (muscle wasting). Studies show that regular muscle exercises can largely stop sarcopenia. In addition, reinforcing the connective tissue makes it possible to reduce the effects of physical trauma, which is one of the main causes of death at later ages. Moreover, exercise increases the success of physical rehabilitation, if necessary.

Of course, genetics also play a role in muscle development. First of all, genetics determines the upper limit at which muscles can develop (although this limit is quite difficult to determine). But more importantly, type 1 muscles (“tonic muscles” or “slow-twitch muscles” or “slow oxidative fibers” and type 2 muscles (“phasic muscles” or “fast-twitch muscles” or “fast glycolytic muscles”) in an individual’s body Moreover, genes can affect the ratio of type 2a muscle (or “fast oxidative glycolytic muscles”) and type 2b muscle (“fast glycolytic muscles”) fibers, which are also known as subgroups of type 2 muscles. The soleus muscle, also known as the “nail muscle”, contains 25–40% more type 1 fibers, while the triceps muscles contain 10–30% more type 2 fibers than other arm muscles, one of the main reasons why this range varies from person to person. one is genetics and the other is environmental conditions such as nutrition and exercise.

How Does New Muscle Formation Experience?

First of all, we need to understand that new muscles cannot be formed in the human body through muscle work. Only existing muscles develop and become stronger. Interestingly, however, exactly how this muscle-building mechanism works has yet to be discovered. However, many different explanations have been developed to date. Understanding these can help you understand where we are in scientifically solving this mystery.


Lactic Acid Hypothesis

This hypothesis, developed in the 1960s, suggested that the molecule responsible for the development of muscles was lactic acid, and that as lactic acid accumulates in the muscles, the muscles get stronger and larger. This hypothesis has been completely falsified and refuted today.

An important detail we can learn from this hypothesis, however, is the role of lactic acid: During intense exercise, the energy expenditure in our muscles increases rapidly. In general, our metabolism tends to consume energy sources produced using oxygen (so sugars can be burned very quickly). These are called aerobic methods. However, if the exercise continues intensely, enough oxygen may not be sent to the muscles. In this case, it is possible to switch to anaerobic energy methods that do not consume oxygen.

Anaerobic energy is obtained by converting glucose (the main sugar molecule consumed in our body) to pyruvate through a process called glycolysis. While there is normally plenty of oxygen in the body, pyruvate can be broken down into further subunits and used to produce more energy. But when oxygen is limited, the body converts pyruvate to another chemical called lactate (or lactic acid), and lactate breaks down glucose, allowing us to continue producing energy. In this way, our muscles can continue to produce energy for 1–3 minutes even in oxygen deprivation. However, during this time, lactate accumulates in the muscles and this begins to damage the tissues.


As the amount of lactate in the body increases, so does the acidity of our muscles (the pH value decreases). Accordingly, the metabolites involved in the normal working processes of the body begin to fail to function properly in this highly acidic environment. Even the chemical pathways that cause lactate accumulation from the very beginning cannot continue to operate in this environment. As a result, the energy production of the muscles decreases rapidly and the work being done (for example, lifting weights) can no longer continue. That’s why you can’t lift a weight forever, and no matter how strong your muscles are, there will always be a limit.

This feedback loop results in muscle relaxation and it is possible to return to adequate oxygen levels as energy expenditure is reduced. Thus, the accumulated lactate is broken down and the muscles are restored. However, this does not happen immediately and can take several days after training. That’s why it’s so important to rest after workouts, as we’ll see later. In addition, the molecule that causes muscle pain is not lactate, but other metabolites produced together with lactate; however, it is not known exactly which of these metabolites causes muscle pain.

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