What should we know about proteins?

After analyzing the calorie balance of the diet, the next key factor is the macronutrients, i.e. the nutrients that we need in large quantities, such as proteins, carbohydrates and lipids. We have already seen the importance of planning a varied diet to ensure adequate intake of these macronutrients.

In this presentation we will explore what proteins are, what functions they serve in our body, and which foods provide the most and best quality protein.

Why are proteins essential for physical fitness?

Proteins are macromolecules made up of chains of amino acids, and are part of all living tissues. The sequence of these amino acids determines the structure and function of each protein.

They are vital for life due to their numerous functions. The following are the most relevant to improve physical condition:

• Plastic or structural function: they are the fundamental component of cells and tissues, indispensable for the growth, repair and renewal of body tissues. They provide solidity and elasticity to muscles, tendons and organs.
• Contractile function: They facilitate muscle contraction. For example, myosin and actin, proteins present in muscles, enable their contraction.
• Transport function: Proteins transport substances throughout the body. An example is hemoglobin, which transports oxygen from the lungs to the tissues and carbon dioxide back to the lungs.

• Defensive function: They protect the body from external agents. For example, glycoproteins produce immunoglobulins, which defend the body, and keratin protects the skin.
• Enzymatic function: They facilitate the chemical reactions of metabolism. An example is sucrase, which transforms common sugar into glucose and lactose for digestion.
• Energy function: Although not ideal, proteins can also be used as a source of energy if not enough fats or carbohydrates are available in the diet.

After reviewing these functions, it is clear that protein is crucial in diets aimed at improving physical fitness, as it promotes muscle growth and repair, vital for increasing physical strength and endurance.

Which proteins are of higher quality?

The quality of a protein is measured by the proportion that can be absorbed and utilized by the body. According to this criterion, proteins are classified into:

• Proteins of high biological value: they contain all the essential amino acids in the right proportions. These proteins, generally of animal origin, are similar in composition to body proteins. Examples include breast milk, eggs, fish and meat.

• Proteins of lower biological value: They do not contain all the essential amino acids in adequate amounts. These proteins, of vegetable origin, do not provide all the necessary amino acids. Examples include soybeans, corn, peanuts, oats and brown rice.

How to obtain quality proteins without consuming foods of animal origin?

By correctly combining protein-rich plant foods, it is possible to obtain high-quality protein. For example, cereals such as rice and wheat are deficient in lysine but rich in methionine, while legumes, such as chickpeas, are rich in lysine and deficient in methionine. By combining the two, as in a dish of rice with chickpeas, this deficiency is compensated and a protein of high biological value is obtained.

In this way, it is not necessary for athletes to include animal proteins in every meal, since by consuming a variety of vegetable proteins they can obtain a protein quality comparable to that of animal origin.

In our next presentation, we will see how to calculate the right amounts of protein to consume.