What is the effect of protein foods on physiologic function in athletes?

With the increasingly competitive sports, in order to achieve excellent results, athletes in the usual training needs to constantly challenge the physical limit to withstand the super-load movement, the body is in a long-term water loss, protein decomposition, electrolyte loss faster state, so a reasonable dietary nutrition is to maintain the health of the athlete and the normal training of the basic material security.
Muscle strength is the fundamental guarantee of human movement, protein is the main substance of the body’s muscle composition, and is the raw material for athletes’ muscle repair. And from the dietary absorption of protein efficiency is low, will also bring in too much lipid, so protein nutrition research for athletes to achieve good results to provide favorable material protection.
Categories of protein nutritional food
Protein nutrition food is mainly divided into protein powder, amino acid, peptide nutrition food, the main function is to provide the human body with high-quality protein to maintain protein metabolism in a relatively balanced state and promote muscle repair and synthesis. From the source of protein can be divided into plant proteins, animal proteins, from the processed form can be divided into solid powder and liquid drinks.

1.1 Plant-based protein soy protein is a high-quality protein, containing high lysine, sulfur-containing amino acids such as methionine and tryptophan content is low, has a high nutritional value, the protein content of tofu can be up to 16.2%, and lipids content is appropriate.
Soy peptide is a soy-based sports supplement developed by using soybean purified protein powder or fermented soybean dregs as raw materials, and by using the compound enzyme digestion method to enzymatically dissolve large protein molecules into peptides. Soy peptide after enzymatic processing can effectively remove the soy protein soy flavor, greatly improve the taste of the consumer, and improve the instability and non-absorbability of soy protein.
Walnut protein contains high phospholipids, is a kind of high-quality plant protein, the digestive utilization rate of the human body can reach 85%, has a very high value of development and utilization, after the compound enzyme digestion of walnut peptide hydroxyl radical scavenging rate reached 84.07%, DPPH radical scavenging rate reached 92.63%.
In order to enrich the nutritional type of protein and improve the taste of beverages, a variety of plant proteins can be mixed to prepare composite beverages, such as black beans and walnuts composite plant protein drinks.
The seed kernel of ginkgo is rich in nutrients and specific chemicals, and its polypeptide has a strong scavenging function of free radicals, which can delay aging to a certain extent. In recent years, the development of ginkgo protein composite drinks is also becoming more mature.
1.2 Animal protein milk is a well-known health food, whey protein is present in the whey of cow’s milk in a class of high nutritional value of proteins, rich in essential amino acids and a complete range, the proportion is moderate.
Whey protein contains a variety of nutritious proteins, and its utilization efficiency is higher than that of free amino acids due to its characteristic of not coagulating under acidic conditions and its high concentration of the branched-chain amino acids leucine, isoleucine and valine, which are essential for the growth and repair of muscle tissues.
Protein bars are mainly made of high quality whey protein, which is a solid high protein product with dietary fiber and probiotics in proportion.
Silkworm pupa is rich in protein, of which the protein content in dried pupa can reach half, and its molecular weight is 75-375 thousand. Generally through the compound enzyme digestion of large molecules of silkworm pupa protein enzymatically dissolved into easily absorbed peptides, which contains more than half of the essential amino acids, but also rich in riboflavin and trace elements and other nutrients, in addition to supplementing the body nutrients, but also has the ability to promote growth and development, anti-fatigue, and so on [32,33].
Insect proteins have a very high content of essential amino acids and can be easily digested and absorbed, and they have many active functions such as regulating immunity, so it is possible to prepare protein functional drinks by mixing various insect proteins such as cicada proteins, silkworm chrysalis proteins, ant proteins, and so on. The efficacy of different protein nutritional foods for athletes is shown in Table 1.

Protein Foods for Athletes
Protein nutritious food has various effects on athletes, which are summarized in the following aspects.
2.1 Muscle building effect: Since protein is the source of life and the basic component of muscle, protein nutritious food has better muscle building effect.
You Lirong experimental research found that 20 fitness enthusiasts and 20 bodybuilders after half a year of soy peptide sports supplements to drink, the muscle content are effective in improving and can reduce the body fat of those who eat.
Liu Na found that soy peptides can effectively increase muscle mass and muscle strength.
Sun Hui conducted a 3-month tracking study with a level 1 athlete, and found that the insect protein functional drink had a positive effect on the muscle condition.
It was found that the protein powder from rats and cows could significantly increase the muscle mass of the athletes and improve the strength of the leg muscles.
Nutritional supplements have the function of easy absorption and promoting muscle fiber synthesis, thus achieving the effect of muscle building and repairing muscle micro-damage.
2.2 Relieve exercise fatigue protein nutrition food generally has the function of scavenging free radicals and lowering serum urea nitrogen, so as to relieve exercise fatigue.
Dong Ya will be 40 Beijing Sports University swimming students aged 22 to 23 years old between the students for a period of three months to take by the whey protein as the raw material for the development of the protein bar found that the protein bar on the athletes undergoing prolonged training has the effect of relieving fatigue.
It was found that whey protein can provide raw materials for the synthesis of glutathione (GSH), which has the function of scavenging free radicals, so whey protein can reduce the fatigue of athletes.
Xu Jiayu et al. through the metabolites of blood lactate, serum urea nitrogen and liver glycogen as an indicator of the athletes who take silkworm pupa protein testing found that silkworm pupa protein to accelerate the removal of blood lactic acid after strenuous exercise and increase the body’s glycogen reserves, thereby alleviating fatigue, because of the silkworm protein is rich in free amino acids and biologically active peptides.
Exercise fatigue is related to the content of branched-chain amino acids in human blood, the presence of branched-chain amino acids can reduce the production of free radicals, weaken the central fatigue Nerve sensitivity, so as to achieve the effect of fatigue relief.
2.3 Enhance immune function Protein food can provide rich immunoglobulin for the human body, so as to enhance the function of athletes’ immunity.
Wang Yimin et al. conducted a 3-month research on 26 athletes and found that taking whey protein can significantly increase the immunoglobulin content of the human body, thus strengthening the body’s immunity.
Because whey protein contains lactoferrin, immunoglobulin, tissue growth factor and so on, these macromolecules have certain immunomodulatory function.
Whey protein can provide sufficient cysteine for athletes, increase the number of monocytes, and improve the immune function of the body.
Guo Jian et al. found that mung bean polypeptide can improve the immunity of mice by increasing the value-added capacity of lymphocytes and the ability to produce antibodies. Since humans and mice are closely related, the efficacy of mung bean peptides on humans needs to be further investigated.
Summary
Due to the large molecular weight of protein, it is not easy to be absorbed and utilized by the human body in a short period of time. It has been found that the active peptides produced by enzymatic digestion of large molecular proteins are more functional, and have the functions of anti-exercise fatigue and immunity enhancement.
For example, it is found that seaweed peptide can increase the content of cortisol and immune factor in athletes’ body so as to improve athletes’ endurance, banana peptide has the effect of repairing athletes’ skeletal muscle, antioxidant and eliminating fatigue, and peanut peptide can relieve fatigue by clearing the content of SOD in the body.
Based on the characteristics of high absorption efficiency and strong functional effect, peptides and branched-chain amino acids, which are the decomposition products of protein, will be the hot spots in the research of protein nutritional food.
Athletes are in the state of high-intensity sports preparation and competition for a long time, and their bodies are facing the loss of water, electrolytes, protein and other nutrients for a long period of time, so they need to supplement their bodies with nutrients from various aspects.
Functional beverages on the market are sports nutritional food made of water, inorganic ions, vitamins, amino acids, and related functional active substances according to certain ratios and formulas. Protein can preserve water, electrolytes, protein and other nutrients, from various aspects for the body to supplement nutrition, such as muscle building, sports fatigue relief, promote immune function enhancement, etc., for athletes is extremely important and necessary, the application of currently known nutritional efficacy of the ingredients, the design of sports nutrition with a specific role in the combination of food formulas, but also the current R & D hotspots.

At present, the development of sports nutrition food at home and abroad is rapid, the research and development from focusing on athletes to popularize to the public, from a single nutritional supplement to a variety of balanced nutritional supplement, from simple processing and purification to pay attention to product quality, safety and taste.
Protein nutrition food can effectively improve the rate of muscle synthesis of athletes, repair the micro-damage of muscle and skeletal muscle, relieve fatigue, enhance immunity, which is the focus and hotspot of sports nutrition food research and development.