Structural proteins and muscle proteins, whey, casein and collagen

As bodybuilders know very well, protein is necessary for the synthesis of their own muscle proteins. For this purpose, a sports diet with an average amount of 1.5 to 2 grams of protein per kilogram of body weight is suitable for strength sports and bodybuilding in particular. This means that excessive values ​​are of no interest, but that you must eat meals sufficiently rich in protein during the day. Eating a very high amount of protein is not useful, as excess protein is converted into energy. However, nutritional needs for protein vary with age. The older you get, the more this minimum amount will increase. This is a rule that also applies to collagen, for example, one of the structural proteins present in the human body.

Aging of the body will lead to an increased demand for amino acids. After 60 years, taking 2.4 g of protein per kilo of body weight would not be extravagant, especially for sedentary people. As you know, sarcopenia leads to a radical decrease in protein assimilation. Thus, to supplement your protein intake, a shake before or after training is an interesting method because it contributes to the essential intake of amino acids without generating unnecessary caloric surpluses. As such, the market is abundantly supplied with proteins of dairy origin ( whey , casein), animal or vegans (peas, rice, etc.).

Proteins contain amino acids, the nitrogenous bases that make up muscle itself

If the proteins you assimilate contribute to the synthesis of your muscle fibers, it is thanks to the amino acids they contain; it is obvious. By definition, these are organic acids linked to an amine base (NH2 + COOH) plus a different radical for each of them. Each amino acid is assigned to different functions in the body, but they will also assemble to create peptides. Here too, thousands of different peptides have specific functions. Peptides greater than 50 amino acids (on average) then assemble to form functional proteins.

These proteins make up the tissues of your organs, muscles, and the supporting organic structures of the entire body, including connective tissues. These are structural proteins, as opposed to muscle proteins, which are necessarily found in muscle. The latter are necessarily composed of essential amino acids, including the famous BCAA For example, muscle and structural proteins fall into a very specific category: fibrous proteins. Thus, fibers need these amino acids, much like building blocks of thousands of long filaments that combine to form muscle or collagen fibers.

Amino acids from food will help synthesize your organic proteins, like a Lego set.

In terms of food, amino acids come from all sources of protein that can be assimilated by humans, whether of animal origin (meat, fish, eggs, milk, cheese, dairy products, etc.) or plant origin (soy, peas, legumes, cereals, etc.). Naturally, an amino acid of animal origin will have strictly the same value as the same amino acid of plant origin. Only the aminogram will testify to the relative quality of a protein , that is, the balance between the different amino acids present in this same protein. But once assimilated by the intestines, your body will synthesize its own peptides and proteins from these molecular bases, a bit like a puzzle or a Lego set.

Obviously, the synthesis of muscle or structural proteins depends on the same dietary amino acids. Some of these amino-functional molecules will be more present in one type of protein or the other. For example, glycine, lysine, and proline will be the majority for collagen, while BCAAs, alanine, and methionine will be the majority in muscle proteins.

Dietary amino acids contribute to the synthesis of human structural and muscle proteins

Your muscles will then use these basic molecules to maintain or increase their own mass and volume. This is the principle of hypertrophy, allowing a muscle mass gain rapid in order to compensate for a partial tearing of muscle fibers, as occurs after intense weight training exercises. Hypertrophy then makes it possible to compensate for a relative lack of muscle strength by adapting by strengthening the existing fibers, which results in a gain in muscle mass and volume. More rarely, new fibers will be synthesized to allow this adaptation relative to resistance exercise.

Structural proteins in the human body make up the majority of proteins in our body

Structural proteins are more abundant than muscle proteins. They are found throughout the body. They are mainly collagen, elastin, keratin, and fibrinogen. Collagen is the most abundant fibrous protein in vertebrates, and therefore in humans as well. It is found abundantly in the skin , tendons, in joints, cartilage and muscles. Collagen present in muscle mass is the main constituent of the sheaths that surround muscle fibers.

Without collagen, muscle contraction would be impossible since it would not function. This protein has a certain rigidity. In contrast, elastin is more flexible. As for collagen, It comes in the form of long peptides composed of a sequence of three amino acids. Glycine is found every 3 amino acids in the polypeptide chain.

Keratin, a structural protein little known to the general public

Keratin is often presented as the protein of hair, but not only that. It is also present in the epidermis and nails. It is a protein that protects the body against the external environment. The peptides that compose it have numerous disulfide bonds (with two sulfur atoms) that strengthen its structure. It is one of the most resistant proteins in the human body. Finally, fibrinogen is a protein found in blood plasma. It allows blood to clot. With thrombin, fibrinogen combines to form fibrin. It clumps together to form a clot. Note that the formation of a clot is necessary under certain conditions, both pathological and serious in other situations.

Naturally, the fibrous proteins best known to athletes are muscle fibers themselves. They are composed of actin and myosin, as well as titin, which plays an important role in force release. Myosin is linked to actin to form a functional protein called actomyosin.

What are the main characteristics of food proteins?

Currently, a plethora of protein powders are available on the sports nutrition market. Whey is at the top of the list. The evolution of industrial processes allowing its marketing on a global scale has led to the growth of this protein. Completely soluble in water, the famous "whey" is especially rich in amino acids and peptides of all kinds. The balance of its aminogram is exceptional due to its high concentration of Leucine, BCAA, Glutamine and Arginine, amino acids essential for muscle anabolism.

Casein is almost as nutritionally interesting as whey. Because its protein is tightly bound by groups (micelles), casein is absorbed much more slowly than whey. As part of post-exercise muscle growth, which takes place over several days, casein should not be overlooked. Indeed, it provides the body with amino acids for several hours, which corresponds very well to the mechanisms of hypertrophy in trained muscles.

How important are muscle proteins versus structural proteins?

Let's just say that the topic has come up more frequently since the arrival of collagen powder on the sports nutrition market. Several factors need to be taken into consideration here. On the one hand, chronic collagen deficiency Glycine in our diet has been noted by scientific research. This deficiency is linked to a genetic defect that is quite common in mammals. It is said to be around 6 to 8 grams per day in humans. On the other hand, the absence of gelatinous meat in our diet does nothing to resolve this nutritional problem, which has repercussions on many areas, with longevity at the forefront.

In addition, the aging is a factor that plays a role here. As you age, your need for glycine and collagen increases. Again, science has proven that beyond a certain age, collagen becomes just as necessary for muscle growth as muscle protein. Clearly, if you want to maintain muscle after age 60, taking a collagen powder will be just as essential as a high-protein diet to maintain your body integrity as you age.