# Protective Effect of Amino Acids on the Muscle Injury of Aerobics Athletes after Endurance Exercise Based on CT Images

Authors: Xianghai He; Yingjun Zhang
Journal: Journal of Healthcare Engineering
 (2022)

---

## Abstract

During the training process, the aerobics athletes gradually increase their technical movements, the appreciation of the movements has been gradually improved, and the injuries of the athletes themselves have also gradually become serious. Based on CT image analysis, we study the protective effect of amino acids on aerobics athletes’ muscle injury after endurance exercise. There are three major substance metabolism disorders in patients with muscle sclerosis, which are mainly manifested as decreased glucose tolerance and insulin resistance. Some patients develop muscle-derived diabetes. At the same time, the synthesis of lipids such as cholesterol and apolipoproteins decreases, the production of ketone bodies increases and the body uses more ketones for energy. The BCAA/AAA factor refers to the branched-chain amino acid/aromatic amino acid (BCAA/AAA) value. In amino acid metabolism, plasma albumin decreased significantly, the ratio of amino acids was unbalanced, and BCAA/AAA decreased, which was more likely to induce muscular encephalopathy. Using computer tomography (CT) to study the protective effect of amino acids on muscle injury, 32 aerobics athletes were randomly divided into an intervention group (Ig) and a control group (CG), each with 16 people. After 64-slice spiral CT scanning of muscles and three-dimensional reconstruction, the intervention group and the control group participated in aerobic endurance training 3 weeks in advance to establish a muscle microinjury model. The intervention group took the preprepared BCAA, while the control group did not take it. After three weeks of training, there will be one hour and three hours of aerobics competition. We need to detect changes in blood glucose (BS), creatine kinase (SCK), lactate dehydrogenase (LD), alanine (ALA), and alanine aminotransferase (AA) before and after exercise and 1 hour after exercise and record AVS athletes' pain analysis table. We successfully established the muscle injury model, letting all athletes’ VAS score in 6–8 points; after 1 hour of exercise, the measurement results were the same as those of 2 hours. Therefore, after endurance training, the blood glucose content of the intervention group gradually decreased and returned to the original level after 2 hours of exercise, while the control group was lower than the level of exercise after 2 hours of exercise; the content of alanine in the two groups decreased more after 2 hours of exercise; the results of serum creatine kinase in the intervention group were higher than those in the control group after exercise. In the intervention group, lactate dehydrogenase increased rapidly at 2 hours after exercise; the alanine aminotransferase in the intervention group increased after exercise, but there was no significant change in the control group. It is also concluded that the longer the exercise time and the more energy consumption, the more effective the branched-chain amino acids supplement will be. The obtained imaging data can provide a more intuitive and accurate basis for the scientific selection of athletes, and amino acids can promote the synthesis of hormones, accelerate the synthesis of proteins and other products, reduce the content of creatine kinase in the blood, and protect the rapid recovery of muscle damage.


---

## Body

## 1. Introduction

Competitive aerobics [1] is evolved from fitness aerobics, with many similar characteristics. For example, music is an indispensable element of both. Athletes arrange their own movements according to the music rhythm and theme background and use their flexibility and strength to complete a set of difficult and natural movements. Aerobic exercise [2] has seven basic steps. Designers can arrange and combine them at will to get better display effect and improve performance difficulty. Therefore, competitive aerobics is not only a simple sport but also a combination of wisdom. At the same time, in order to make the athletes perform the choreographer’s designed movements perfectly, we must improve their own physical quality. Perfect body shape, soft toughness, and strong body strength are essential. Although competitive aerobics is not included in the current Olympic Games, with its separation from fitness aerobics, more and more countries begin to attach importance to it. This is possible in the future Olympic Games. Although our country has made some progress in the field of aerobics, after all, China has not been exposed to this project for a long time. Therefore, it is necessary and urgent to study the protective effect of BCAA on muscle injury after endurance exercise.In the study of muscle injury, classifying CT images of muscle injury based on historical data can provide early prevention and treatment of some lesions, improve the cure rate, and assist doctors in the diagnosis of muscle injury. In machine learning, image labels are used to label the attributes of the entire image, which are used to train a classifier based on the entire CT image. One might think that hospitals would store labels on CT images.Although the treatment of muscle strain has made substantial progress, muscle strain is still a very destructive disease, the incidence of muscle injury is still very high, and different from other diseases, skeletal muscle is the most abundant human tissue, and bone and iliac muscle injury is one of the most common sports injuries, so muscle strain urgently needs new and effective treatment methods. Mesenchymal stem cells (MSCs) have become important target cells for tissue engineering research and other diseases treatment because of their unique characteristics such as abundant sources, simple preparation, multidirectional differentiation ability, and low tumorigenicity. It is exciting that MSC [3] has achieved initial success in the treatment of muscle injury. The study of muscle injury found that when muscle injury occurs, an inflammatory response occurs in the first stage, and inflammatory cells can freely invade, due to vascular tear or vascular permeability increased significantly, leading to the accumulation of inflammatory factors in the injured site. After several hours of damage, white blood cells and monocytes eventually become macrophages. Macrophages have two functions. First, they remove necrotic muscle fibers by phagocytosis. Secondly, together with fibroblasts, they produce chemotactic signals, such as growth factors, cytokines, and chemokines. The extracellular matrix also contains growth factors, which become active when tissue is damaged. The next stage is the repair phase. The first is muscle fiber regeneration, also known as mycoplasma or basal layer muscle fiber regeneration under satellite cells. Muscle satellite cells proliferate and eventually differentiate into myoblasts. Muscle injuries have always plagued athletes, and along with athletes’ training and competition, muscle injuries will have a greater negative impact on training effects and competition results to a certain extent. In severe cases, they may even cause muscle damage, causing athletes to stop training and withdraw from competitions. Therefore, it is very necessary to grasp the changes of muscle injury. Because these new myoblasts fuse with the injured muscle fiber, both ends of the injured muscle fiber are refilled. The second repair stage is the process of connective tissue forming cancer scar tissue. Scar tissue provides a location for fibroblasts to invade granulation tissue. However, if these fibroblasts proliferate excessively, the injured muscle will form scar tissue, which not only interferes with the repair process but also blocks the process of muscle regeneration. In addition, due to the injury, the nerve tissue in the muscle is damaged, which makes the muscle fiber lose the nerve innervation and the nutritional function of nerve cells, which is not conducive to the healing process of the injured muscle. HGF, IL-1, and IL-6 are secretory factors that stimulate satellite activity. In a word, it is an indisputable fact that there is a protective function of muscle after injury.Abnormal amino acid metabolism is mainly manifested in the decrease of serum albumin, the increase of blood ammonia, and the imbalance of amino acid ratio. The liver is the main place for protein synthesis. It can synthesize almost all plasma proteins except immune proteins. In liver cirrhosis, liver function declines due to the damage and number of liver cells, as well as unreasonable diet restrictions, resulting in a significant decrease in plasma albumin and hypoproteinemia. However, hypoalbuminemia easily induces brain edema, makes brain cell dysfunction, and promotes the occurrence of hepatic encephalopathy. Branched-chain amino acids [4] are essential amino acids for the human body, including leucine, isoleucine, and valine. They are called “branched-chain amino acids” because they have typical side chains. BCAAs [5] have a variety of physiological functions. BCAAs are not only the basic unit of the peptide chain but also involved in the synthesis of sterols, ketones, and glucose. The final products of BCAAs metabolism are acetyl coenzyme A and succinyl coenzyme A, which enter the mitochondria and generate energy through the tricarboxylic acid cycle. In addition, BCAAs, especially leucine, can activate the mTOR signaling pathway and promote protein synthesis, cell metabolism, and cell growth. However, excessive BCAA is harmful. High BCAAs were positively correlated with dyslipidemia, insulin resistance, obesity, and type 2 diabetes. Although most amino acids are synthesized and decomposed in the liver, the metabolism of BCAAs is mainly concentrated in nonliver tissues, such as the myocardium, neurons, and kidney. Therefore, the changes of BCAAs metabolism may be involved in the occurrence and development of CHF metabolic remodeling. However, so far, there is no data to prove whether there is a correlation between plasma BCAAs level and CHF. In addition, in the normal body, the metabolic waste ammonia enters the ornithine cycle to synthesize urea through the liver, while liver cell metabolism is impaired in liver cirrhosis, the ornithine cycle is blocked, and a large amount of ammonia accumulates in the body, so blood ammonia rises. In patients with liver cirrhosis, the body environment is disordered, especially the metabolism of amino acids. Due to insufficient intake of plasma amino acids and increased consumption of peripheral muscle tissue in patients with liver cirrhosis, BCAA is lower than normal.If the protective effect of muscle injury is not in place, it will do great harm to the muscle, and the athletes can neither play the real state nor participate in high-intensity sports in time, which will have a great impact on the collective and individual. In the process of generating muscle CT images, due to machine performance or scanning technology and other reasons, there will be large differences in the quality of the generated images. Therefore, the preprocessing of images has become an indispensable stage before data analysis. Moreover, as the amount of data continues to increase, the preprocessing operations involving manual participation have been unable to meet the needs. In this paper, the research on the protective effect of branched-chain amino acids on muscle injury of aerobics athletes after endurance training has solved this problem. The main structure of this paper is as follows: firstly, the development status of branched-chain amino acids is elaborated, and the muscle injury is briefly introduced; secondly, the model of muscle injury after endurance exercise of aerobics athletes is established, in which the mechanism of endurance exercise, the repair method of muscle injury, the training scheme of aerobic endurance exercise, and the successful target of muscle injury in endurance exercise are established. Then, it introduces the protective effect of BCAA on muscle injury after endurance training, including the composition and function of BCAA, the mechanism of BCAA catabolism, the physiological function of BCAA, the biosynthesis pathway of BCAA, and the protection mechanism of BCAA on muscle injury. Surface electromyography is one of the methods to assess muscle fatigue. It is a noninvasive technology that records, measures, and evaluates skeletal muscle function through the skin surface above the muscle. The real-time monitoring of fatigue and the fatigue status of specific muscles can be measured, and the mutual changes of biomechanics and physiology in the process of muscle fatigue can be obtained. Finally, through the formulation of an endurance exercise program, the experimental results of sports injury show that proper supplement of branched-chain amino acids can reduce the contents of creatine kinase and lactate dehydrogenase in blood, protect muscle tissue structure, and alleviate muscle injury caused by endurance training.


## 2. Establishment of the Muscle Injury Model of Aerobics Athletes after Endurance Exercise

### 2.1. Overview of Endurance Sports

Combining the popular deep learning or machine learning with tomography helps not only in image analysis but also in image reconstruction. The most widespread application of machine learning in CT image reconstruction is depth imaging [6]. Endurance exercise [7] usually refers to the ability to perform certain high-intensity behaviors for a long time. Functional ability refers to the ability to use functional potential effectively and the psychological strength of athletes which are important factors to determine the endurance level of aerobics athletes. The invention provides a CT image prediction method based on deep learning. Because the aerobics competition time is generally 1 minute 20 seconds ± 5 seconds, aerobics athletes have been carrying out high-intensity, high difficulty movement, which will make the heartbeat faster than the general action. Therefore, the vast majority of aerobics coaches do not think they are engaged in aerobic exercise. For homogeneous materials, the incident intensity and output intensity of single-energy X-rays conform to Lambert–Beer’s law.(1)I=I0e−uax.For nonuniform objects, that is, different attenuation coefficients everywhere, the object can be divided into small units to calculate the attenuation characteristics. That is, when the outgoing beam of the previous unit is the incident beam of the next unit, it can be expressed as follows in the form of cascade in mathematics:(2)I=I0e−u2axe−u1axe−u3ax⋯e−utax=I0e∑n=1Nunax.The incident X-ray intensityI0 does not change, so(3)II0=e−u2axe−u1axe−u3ax⋯e−utax=e∑n=1Nun∇x.Most of the sports injuries of outstanding competitive aerobics athletes in China are concentrated.Born during the training period, the high difficulty of training, high intensity, and long time are the main reasons for the high probability of injury to athletes during this period, mostly in the wrists, ankles, and knees. Through some physiological knowledge, we can know that when a person is engaged in anaerobic exercise for more than 8 seconds, the energy of the body mainly comes from the conversion of glycogen and glucose, which will produce lactic acid. In the process of conversion, lactic acid accumulation will definitely cause muscle soreness, and some will become powerless from heart exercise; this is also an important reason why many aerobics athletes often make mistakes after the competition. Take the logarithm of both sides of the equal sign of the above equation to get the following:(4)P=−lnII0=lnI0I=∑n=1Nμn∇x.When the unit size is infinitely small, we can get(5)p=py=∑n=1Nμx,y⋅∇X.Aerobic capacity refers to the work done by the body to provide energy from the oxidative decomposition of energy substances under the condition of sufficient oxygen supply. It is based on the characteristics of skeletal muscle, neuromodulation ability, energy supply characteristics, etc. It is one of the important indicators of human health.Therefore, in order to achieve good results, aerobics athletes must carry out endurance training in daily training. When your body adapts to a certain intensity of exercise, even if you will still feel tired in the future, your resistance will be greatly improved, and your endurance will also be improved, as shown in Figure1:Figure 1
Contraction force-speed curve and contraction force-length curve.At the same time, competitive aerobics is a kind of anaerobic exercise, which is obviously different from other anaerobic sports such as 100 meters dash. Because it does not have a single exercise composition, it contains a variety of sports, so in anaerobic training, we should also pay attention to aerobic training. Aerobic exercise and anaerobic exercise are not antagonistic, but interrelated.(6)Wij=N11N00−N01N10N11N00+N01N10,(7)Wsv=2LL−1∑i=1L−1∑k=i+1LWi,j.In order to get rid of the long-term physical training, the athletes must combine the two kinds of sports to improve their endurance. No sport has only one mode of energy supply, just the proportion of which mode. Therefore, although aerobic exercise is a kind of anaerobic exercise, we should pay attention to the training of aerobic exercise, so that the oxygen uptake of muscles can be improved [8].(8)Lij=N11N10−N01N10N11+N10N01+N00N11+N01N10+N00.


### 2.2. Establishment Mechanism of Muscle Injury

The common symptom of exercise-induced muscle injury is muscle soreness, which is transmitted by myelinated type III afferent nerve fibers and unmyelinated type IV afferent nerve fibers. The measure of inconsistency is(9)Wisij=N01+N10N11+N01+N10+N00.There are 6 types of unpaired difference measures:(1)
Entropy measurement method:(10)Q=1N∑j=1N1L−L/2minlZjL−lZj.(2)
Kohavi–Wolpert measurement method:In 1996, Kohavi and Wolpert proposed the KW measurement method as follows:(11)KW=1NL2∑j=1NlzjL−lzj.From this, the relationship between KW and it can be drawn:(12)KW=L−12LDissv.(3)
Interrater agreementℜ measurement:(13)p¯=1NJ∑j=1N∑i=1Lyi.j.Then, the calculation formula ofκ is(14)κ=1−1/L∑j=1NlzjL−lzjNL−1P¯1−P¯.(4)
Difficultyθ metric:(15)θ=VarX.(5)
Generalized diversity measurement:(16)P1=∑i=1LiLpi,p2=∑i=1Lii−1LL−1pi.(6)
CFD measurement:(17)CFD=0,11−P0,∑i=1LL−iL−1Pi.It is generally believed that myelinated type III fibers transmit tingling sensation, while unmyelinated type IV fibers transmit dull pain. The latter is more common in delayed onset muscle soreness. In addition, pain is caused by chemicals released during muscle injury and repair, including prostaglandins, vasodilators, serotonin, histamine, and potassium ions.The development process of the muscle injury model is divided into four stages. The characteristics of muscle injury caused by endurance exercise are delay, different exercise intensity, time, and muscle contraction mode, and the duration is from several minutes to two weeks or more. The four stages are as follows:(1)
Initial stage: it is generally believed that the primary injury is caused by mechanical stretch or metabolic factors. Mechanical stretching can damage the membrane of muscle cells (causing calcium ions to enter muscle cells), sarcoplasmic reticulum (resulting in decreased calcium regulation), and muscle contractile components. Metabolic factors include high body temperature, low pH, insufficient mitochondrial oxidation, and increased free radicals. At this stage, the main cause of muscle injury that more research shows is calcium overload and free radical accumulation. However, many of the features of this phase are not clear. This process is mainly related to the causes of the change, and further research is needed. This paper uses Euclidean distance as the similarity measure of the K-means algorithm. Euclidean distance is the distance between points in n-dimensional space.(18)d=∑k=1nx1k−x2k2,(19)d=a−ba−bT.(2)
Spontaneous phase: this stage refers to the destruction of the cellular structure by the intrinsic proteolytic system and lipid peroxidation system of muscle fibers, usually occurring hours before phagocytes invade the injured site. In this stage, the damage of proteolytic enzyme, lysosomal enzyme, lysophosphatidylcholine, and prostaglandin on local tissues is the main reason.(20)djX=maxi=1lci,jX,j=1,2,…,m.(3)
Phagocytosis: it usually occurs 4–6 hours after exercise, lasting for 2–4 days. At this stage, phagocytes invade the injured site, and the protein degradation part of the injured muscle fiber is engulfed. At this stage, it is generally believed that white blood cells (mainly neutrophils, monocytes, and macrophages) play a broad role in the inflammatory response to muscle injury. They have three main functions in the process of muscle injury and repair: attack and decompose debris (neutrophils and macrophages), scavenge cell debris (macrophages), and cell regeneration (macrophages). It is difficult to separate the spontaneous phase from the phagocytic phase.(4)
Regeneration: after degradation, some macrophages participate in muscle repair. In the phagocytosis stage of muscle injury, the surviving satellite cells differentiate into myoblasts and fuse to form new muscle tubules. In this process, macrophages will still invade, and the invasion of macrophages is a necessary prerequisite for regeneration, which may stimulate satellite cell division in some way. However, up to now, there is not enough evidence to prove that the ultrastructural changes of EIMI have cumulative damage.Studies have shown that strenuous exercise and stretching can activate satellite cells to produce mitosis and proliferation, so as to make muscle fibers proliferate or repair damaged muscle fibers. The activation of satellite cells is related to the nature and intensity of stimulation and the response ability of muscle fibers. This stage usually occurs 4–6 days after exercise. Contractile proteins in damaged muscle fibers begin to regenerate. After 10 days, the muscle structure gradually returned to normal.


### 2.3. Repair Methods of Muscle Injury

There are different treatments for muscle injury [9]. According to the severity of the injury, surgical or nonsurgical methods can be adopted. There are many alternatives to nonsurgical treatment (conservative treatment). Drug therapy is one of them. Drugs are divided into traditional Chinese medicine and Western medicine. According to the different ways of use, it can be divided into oral and external use. China is the birthplace of traditional Chinese medicine, which has rich drug resources, long history experience, and systematic theoretical guidance. “See, smell, ask, cut,” “pill, powder, ointment, Dan” is the essence of Chinese medicine. Maximum oxygen uptake and ventilatory threshold are important indicators for assessing aerobic capacity, as well as key indicators for formulating exercise intensity. Therefore, assessing the aerobic capacity of athletes is of great significance for mastering the training effects of athletes and understanding the gap between athletes of different levels. The human body uses a large number of muscles for long-term intense exercise, and when the cardiopulmonary function and the ability of the muscles to use oxygen reach their limit level, the amount of oxygen that can be taken in a unit of time is called the maximum oxygen uptake. The CT value reflects the degree of absorption of X-rays by the human body, thereby showing the density of different tissues. Generally speaking, the CT value of the bone cortex with the highest density of the human body is +1000 Hu, while the air is −1000 Hu. The larger the attenuation coefficient of human tissue to X-ray, the higher the CT value. A medical diagnosis can be made by comparing the calculated CT value with the standard CT value of the corresponding part. Common CT values of human tissues are shown in Table 1.Table 1
CT values of human tissues.
OrganizeCT valueOrganizeCT valueOrganizeCT valueBone tissue>500Blood clotting74∼94Fat−10∼100Calcium90∼400Blood23∼45Water0The CT value of bone tissue is greater than 500, the CT value of coagulation is between 74 and 94, and the CT value of fat is between -10 and 100.For thousands of years, traditional Chinese medicine (TCM) has played an irreplaceable role in treating diseases and saving people. The invention and application of traditional Chinese medicine in China has a long history, and more than 10000 kinds of traditional Chinese medicine have been used so far. Traditional Chinese medicine compound is the characteristic and advantage of traditional Chinese medicine. The so-called medicine is limited, the prescription is infinite, the medicine has the individuality specialty, the prescription has the group clever use, the disease manifests by the card, and the medicine uses the card to form the prescription. “Monarch, minister, assistant, and envoy” is the principle of prescription, while “mutual order, mutual food, and mutual diarrhea” is the law of action. It is based on the holistic view of traditional Chinese medicine and the concentrated embodiment of syndrome differentiation and treatment. In recent years, the research of traditional Chinese medicine compounds used to eliminate sports fatigue and injury has gradually become a hot spot in sports medicine research. The traditional Chinese medicine compound system is the basic characteristic of traditional Chinese medicine. It has incomparable advantages in eliminating, preventing, and repairing sports diseases. We need to understand its medicinal value and clinical application and provide a reliable basis and data for the development of new drugs.


### 2.4. Endurance Exercise Program of Aerobics Athletes

During exercise, oxygen is transported to skeletal muscles, and aerobic metabolism produces energy to contract skeletal muscles. These muscle contractions allow the body to keep moving and meet the intensity of exercise. As the exercise load increases, the energy required to meet this exercise intensity also increases. Therefore, the increase in oxygen uptake will meet the energy demand. Through in-depth interviews with experts, combined with the essence of this study, an elite competitive aerobics athlete endurance training program was constructed. A routine training program was constructed for testing, as shown in Table2.Table 2
Routine training program of aerobic athletes’ sports endurance.
Exercise contentPractice times/groupPractice formPractice requirementsPush-up35 × 5 groupsDo push-ups continuously with no time limitShoulder and elbow levelFrom both ends35 × 5 groupsKeep practicingWhen folding, the fingers touch the toes and the open shoulders must touch the ground400 m turn backTime recording × 3 groupsIn the standard 400 m runway, the time is recorded. 10 m distance, calculate the round-trip markReach your limit speed. Touch the mark with your fingers2′ × 5 groupsSplit (left, right, horizontal)1′ × 5 groupPlace 30 cm pads on the front legs and back to keep the split positionKeep the upper body upright with both hands on the front kneeSupporting swivel (right angle, split leg)20 laps × 5 groupsOn the ground, a complete 360° is used to calculate the number of turnsDuring practice, except for supporting hands, other parts should not touch the groundRaise your hips45 × 3 groupsContinuous contact information, jump back from the push-up state to push-up state, calculate the number of timesPush-up, shoulder parallel to elbow, body folding angle less than 80 degrees, hand touching ankle jointStraddle jump40 × 5 groupsContinuous without time limitBoth feet across the horizontal line at the same time, count the numberVertical split leg (left and right)40 × 3 groupsWith both hands on the ground, one leg to do a continuous vertical splitThe opening is 360 degreesObstacle endurance training (long jump, high platform, climbing handstand, high leg lift, standing, and lying support)(5 times + 3times + 8 meters + 50 times + 30 times) × 5 groupsForm: 20 people in the range of five exercises on average, practice clockwise, in turn, a circle into a groupThe practice process is compact and needs to realize direct and seamless connection between groups


### 2.5. Marks of Successful Model Establishment

Muscle injury caused by high-intensity and unaccustomed exercise can change the function, metabolism, and morphological structure of muscle. Its function is mainly manifested in the decrease of muscle contraction strength and speed. Like muscle fatigue, it is the external manifestation of muscle injury and should not be used as evidence and mark to judge muscle injury. In terms of morphology, both optical microscope and electron microscope can be used as the most direct evidence of muscle injury. At the same time, the increase of muscle enzyme activity, myoglobin, and muscle protein degradation products detected by biochemical method [10] can also be used as indirect evidence and markers of muscle injury. In sports practice, the content of muscle cells leaking into serum is a common index to reflect the degree of muscle cell injury. Of course, with the development of magnetic resonance imaging (EMG), some noninvasive markers of muscle injury, such as MRI, have been used to evaluate muscle condition.Brain CT manifestations of congenital amino acid metabolism disease are as follows. Congenital amino acid metabolism disease mainly affects the nervous system and is one of the important causes of mental retardation in children. In addition, the ultrastructural changes of skeletal muscle only account for a small part of muscle fiber. In addition, for human experiments, due to the limitations of experimental methods, many deep injured muscles are not easy to biopsy. Therefore, some ultrastructural changes of muscle are often ignored in this field, which leads to different experimental results. In order to find the exact evidence and mark of Amy's morphology, it is necessary to conduct in-depth research in this field.In recent ten years, more and more attention has been paid to the biochemical changes during exercise muscle load and recovery period, which is sensitive and accurate indirect evidence. The biochemical indicators of muscle injury mainly include the increase of serum enzyme activity, especially the activity of creatine kinase; the increase of serum myoglobin (MB), and the increase of muscle protein conversion and urinary 3-methylhistidine excretion.


## 2.1. Overview of Endurance Sports

Combining the popular deep learning or machine learning with tomography helps not only in image analysis but also in image reconstruction. The most widespread application of machine learning in CT image reconstruction is depth imaging [6]. Endurance exercise [7] usually refers to the ability to perform certain high-intensity behaviors for a long time. Functional ability refers to the ability to use functional potential effectively and the psychological strength of athletes which are important factors to determine the endurance level of aerobics athletes. The invention provides a CT image prediction method based on deep learning. Because the aerobics competition time is generally 1 minute 20 seconds ± 5 seconds, aerobics athletes have been carrying out high-intensity, high difficulty movement, which will make the heartbeat faster than the general action. Therefore, the vast majority of aerobics coaches do not think they are engaged in aerobic exercise. For homogeneous materials, the incident intensity and output intensity of single-energy X-rays conform to Lambert–Beer’s law.(1)I=I0e−uax.For nonuniform objects, that is, different attenuation coefficients everywhere, the object can be divided into small units to calculate the attenuation characteristics. That is, when the outgoing beam of the previous unit is the incident beam of the next unit, it can be expressed as follows in the form of cascade in mathematics:(2)I=I0e−u2axe−u1axe−u3ax⋯e−utax=I0e∑n=1Nunax.The incident X-ray intensityI0 does not change, so(3)II0=e−u2axe−u1axe−u3ax⋯e−utax=e∑n=1Nun∇x.Most of the sports injuries of outstanding competitive aerobics athletes in China are concentrated.Born during the training period, the high difficulty of training, high intensity, and long time are the main reasons for the high probability of injury to athletes during this period, mostly in the wrists, ankles, and knees. Through some physiological knowledge, we can know that when a person is engaged in anaerobic exercise for more than 8 seconds, the energy of the body mainly comes from the conversion of glycogen and glucose, which will produce lactic acid. In the process of conversion, lactic acid accumulation will definitely cause muscle soreness, and some will become powerless from heart exercise; this is also an important reason why many aerobics athletes often make mistakes after the competition. Take the logarithm of both sides of the equal sign of the above equation to get the following:(4)P=−lnII0=lnI0I=∑n=1Nμn∇x.When the unit size is infinitely small, we can get(5)p=py=∑n=1Nμx,y⋅∇X.Aerobic capacity refers to the work done by the body to provide energy from the oxidative decomposition of energy substances under the condition of sufficient oxygen supply. It is based on the characteristics of skeletal muscle, neuromodulation ability, energy supply characteristics, etc. It is one of the important indicators of human health.Therefore, in order to achieve good results, aerobics athletes must carry out endurance training in daily training. When your body adapts to a certain intensity of exercise, even if you will still feel tired in the future, your resistance will be greatly improved, and your endurance will also be improved, as shown in Figure1:Figure 1
Contraction force-speed curve and contraction force-length curve.At the same time, competitive aerobics is a kind of anaerobic exercise, which is obviously different from other anaerobic sports such as 100 meters dash. Because it does not have a single exercise composition, it contains a variety of sports, so in anaerobic training, we should also pay attention to aerobic training. Aerobic exercise and anaerobic exercise are not antagonistic, but interrelated.(6)Wij=N11N00−N01N10N11N00+N01N10,(7)Wsv=2LL−1∑i=1L−1∑k=i+1LWi,j.In order to get rid of the long-term physical training, the athletes must combine the two kinds of sports to improve their endurance. No sport has only one mode of energy supply, just the proportion of which mode. Therefore, although aerobic exercise is a kind of anaerobic exercise, we should pay attention to the training of aerobic exercise, so that the oxygen uptake of muscles can be improved [8].(8)Lij=N11N10−N01N10N11+N10N01+N00N11+N01N10+N00.


## 2.2. Establishment Mechanism of Muscle Injury

The common symptom of exercise-induced muscle injury is muscle soreness, which is transmitted by myelinated type III afferent nerve fibers and unmyelinated type IV afferent nerve fibers. The measure of inconsistency is(9)Wisij=N01+N10N11+N01+N10+N00.There are 6 types of unpaired difference measures:(1)
Entropy measurement method:(10)Q=1N∑j=1N1L−L/2minlZjL−lZj.(2)
Kohavi–Wolpert measurement method:In 1996, Kohavi and Wolpert proposed the KW measurement method as follows:(11)KW=1NL2∑j=1NlzjL−lzj.From this, the relationship between KW and it can be drawn:(12)KW=L−12LDissv.(3)
Interrater agreementℜ measurement:(13)p¯=1NJ∑j=1N∑i=1Lyi.j.Then, the calculation formula ofκ is(14)κ=1−1/L∑j=1NlzjL−lzjNL−1P¯1−P¯.(4)
Difficultyθ metric:(15)θ=VarX.(5)
Generalized diversity measurement:(16)P1=∑i=1LiLpi,p2=∑i=1Lii−1LL−1pi.(6)
CFD measurement:(17)CFD=0,11−P0,∑i=1LL−iL−1Pi.It is generally believed that myelinated type III fibers transmit tingling sensation, while unmyelinated type IV fibers transmit dull pain. The latter is more common in delayed onset muscle soreness. In addition, pain is caused by chemicals released during muscle injury and repair, including prostaglandins, vasodilators, serotonin, histamine, and potassium ions.The development process of the muscle injury model is divided into four stages. The characteristics of muscle injury caused by endurance exercise are delay, different exercise intensity, time, and muscle contraction mode, and the duration is from several minutes to two weeks or more. The four stages are as follows:(1)
Initial stage: it is generally believed that the primary injury is caused by mechanical stretch or metabolic factors. Mechanical stretching can damage the membrane of muscle cells (causing calcium ions to enter muscle cells), sarcoplasmic reticulum (resulting in decreased calcium regulation), and muscle contractile components. Metabolic factors include high body temperature, low pH, insufficient mitochondrial oxidation, and increased free radicals. At this stage, the main cause of muscle injury that more research shows is calcium overload and free radical accumulation. However, many of the features of this phase are not clear. This process is mainly related to the causes of the change, and further research is needed. This paper uses Euclidean distance as the similarity measure of the K-means algorithm. Euclidean distance is the distance between points in n-dimensional space.(18)d=∑k=1nx1k−x2k2,(19)d=a−ba−bT.(2)
Spontaneous phase: this stage refers to the destruction of the cellular structure by the intrinsic proteolytic system and lipid peroxidation system of muscle fibers, usually occurring hours before phagocytes invade the injured site. In this stage, the damage of proteolytic enzyme, lysosomal enzyme, lysophosphatidylcholine, and prostaglandin on local tissues is the main reason.(20)djX=maxi=1lci,jX,j=1,2,…,m.(3)
Phagocytosis: it usually occurs 4–6 hours after exercise, lasting for 2–4 days. At this stage, phagocytes invade the injured site, and the protein degradation part of the injured muscle fiber is engulfed. At this stage, it is generally believed that white blood cells (mainly neutrophils, monocytes, and macrophages) play a broad role in the inflammatory response to muscle injury. They have three main functions in the process of muscle injury and repair: attack and decompose debris (neutrophils and macrophages), scavenge cell debris (macrophages), and cell regeneration (macrophages). It is difficult to separate the spontaneous phase from the phagocytic phase.(4)
Regeneration: after degradation, some macrophages participate in muscle repair. In the phagocytosis stage of muscle injury, the surviving satellite cells differentiate into myoblasts and fuse to form new muscle tubules. In this process, macrophages will still invade, and the invasion of macrophages is a necessary prerequisite for regeneration, which may stimulate satellite cell division in some way. However, up to now, there is not enough evidence to prove that the ultrastructural changes of EIMI have cumulative damage.Studies have shown that strenuous exercise and stretching can activate satellite cells to produce mitosis and proliferation, so as to make muscle fibers proliferate or repair damaged muscle fibers. The activation of satellite cells is related to the nature and intensity of stimulation and the response ability of muscle fibers. This stage usually occurs 4–6 days after exercise. Contractile proteins in damaged muscle fibers begin to regenerate. After 10 days, the muscle structure gradually returned to normal.


## 2.3. Repair Methods of Muscle Injury

There are different treatments for muscle injury [9]. According to the severity of the injury, surgical or nonsurgical methods can be adopted. There are many alternatives to nonsurgical treatment (conservative treatment). Drug therapy is one of them. Drugs are divided into traditional Chinese medicine and Western medicine. According to the different ways of use, it can be divided into oral and external use. China is the birthplace of traditional Chinese medicine, which has rich drug resources, long history experience, and systematic theoretical guidance. “See, smell, ask, cut,” “pill, powder, ointment, Dan” is the essence of Chinese medicine. Maximum oxygen uptake and ventilatory threshold are important indicators for assessing aerobic capacity, as well as key indicators for formulating exercise intensity. Therefore, assessing the aerobic capacity of athletes is of great significance for mastering the training effects of athletes and understanding the gap between athletes of different levels. The human body uses a large number of muscles for long-term intense exercise, and when the cardiopulmonary function and the ability of the muscles to use oxygen reach their limit level, the amount of oxygen that can be taken in a unit of time is called the maximum oxygen uptake. The CT value reflects the degree of absorption of X-rays by the human body, thereby showing the density of different tissues. Generally speaking, the CT value of the bone cortex with the highest density of the human body is +1000 Hu, while the air is −1000 Hu. The larger the attenuation coefficient of human tissue to X-ray, the higher the CT value. A medical diagnosis can be made by comparing the calculated CT value with the standard CT value of the corresponding part. Common CT values of human tissues are shown in Table 1.Table 1
CT values of human tissues.
OrganizeCT valueOrganizeCT valueOrganizeCT valueBone tissue>500Blood clotting74∼94Fat−10∼100Calcium90∼400Blood23∼45Water0The CT value of bone tissue is greater than 500, the CT value of coagulation is between 74 and 94, and the CT value of fat is between -10 and 100.For thousands of years, traditional Chinese medicine (TCM) has played an irreplaceable role in treating diseases and saving people. The invention and application of traditional Chinese medicine in China has a long history, and more than 10000 kinds of traditional Chinese medicine have been used so far. Traditional Chinese medicine compound is the characteristic and advantage of traditional Chinese medicine. The so-called medicine is limited, the prescription is infinite, the medicine has the individuality specialty, the prescription has the group clever use, the disease manifests by the card, and the medicine uses the card to form the prescription. “Monarch, minister, assistant, and envoy” is the principle of prescription, while “mutual order, mutual food, and mutual diarrhea” is the law of action. It is based on the holistic view of traditional Chinese medicine and the concentrated embodiment of syndrome differentiation and treatment. In recent years, the research of traditional Chinese medicine compounds used to eliminate sports fatigue and injury has gradually become a hot spot in sports medicine research. The traditional Chinese medicine compound system is the basic characteristic of traditional Chinese medicine. It has incomparable advantages in eliminating, preventing, and repairing sports diseases. We need to understand its medicinal value and clinical application and provide a reliable basis and data for the development of new drugs.


## 2.4. Endurance Exercise Program of Aerobics Athletes

During exercise, oxygen is transported to skeletal muscles, and aerobic metabolism produces energy to contract skeletal muscles. These muscle contractions allow the body to keep moving and meet the intensity of exercise. As the exercise load increases, the energy required to meet this exercise intensity also increases. Therefore, the increase in oxygen uptake will meet the energy demand. Through in-depth interviews with experts, combined with the essence of this study, an elite competitive aerobics athlete endurance training program was constructed. A routine training program was constructed for testing, as shown in Table2.Table 2
Routine training program of aerobic athletes’ sports endurance.
Exercise contentPractice times/groupPractice formPractice requirementsPush-up35 × 5 groupsDo push-ups continuously with no time limitShoulder and elbow levelFrom both ends35 × 5 groupsKeep practicingWhen folding, the fingers touch the toes and the open shoulders must touch the ground400 m turn backTime recording × 3 groupsIn the standard 400 m runway, the time is recorded. 10 m distance, calculate the round-trip markReach your limit speed. Touch the mark with your fingers2′ × 5 groupsSplit (left, right, horizontal)1′ × 5 groupPlace 30 cm pads on the front legs and back to keep the split positionKeep the upper body upright with both hands on the front kneeSupporting swivel (right angle, split leg)20 laps × 5 groupsOn the ground, a complete 360° is used to calculate the number of turnsDuring practice, except for supporting hands, other parts should not touch the groundRaise your hips45 × 3 groupsContinuous contact information, jump back from the push-up state to push-up state, calculate the number of timesPush-up, shoulder parallel to elbow, body folding angle less than 80 degrees, hand touching ankle jointStraddle jump40 × 5 groupsContinuous without time limitBoth feet across the horizontal line at the same time, count the numberVertical split leg (left and right)40 × 3 groupsWith both hands on the ground, one leg to do a continuous vertical splitThe opening is 360 degreesObstacle endurance training (long jump, high platform, climbing handstand, high leg lift, standing, and lying support)(5 times + 3times + 8 meters + 50 times + 30 times) × 5 groupsForm: 20 people in the range of five exercises on average, practice clockwise, in turn, a circle into a groupThe practice process is compact and needs to realize direct and seamless connection between groups


## 2.5. Marks of Successful Model Establishment

Muscle injury caused by high-intensity and unaccustomed exercise can change the function, metabolism, and morphological structure of muscle. Its function is mainly manifested in the decrease of muscle contraction strength and speed. Like muscle fatigue, it is the external manifestation of muscle injury and should not be used as evidence and mark to judge muscle injury. In terms of morphology, both optical microscope and electron microscope can be used as the most direct evidence of muscle injury. At the same time, the increase of muscle enzyme activity, myoglobin, and muscle protein degradation products detected by biochemical method [10] can also be used as indirect evidence and markers of muscle injury. In sports practice, the content of muscle cells leaking into serum is a common index to reflect the degree of muscle cell injury. Of course, with the development of magnetic resonance imaging (EMG), some noninvasive markers of muscle injury, such as MRI, have been used to evaluate muscle condition.Brain CT manifestations of congenital amino acid metabolism disease are as follows. Congenital amino acid metabolism disease mainly affects the nervous system and is one of the important causes of mental retardation in children. In addition, the ultrastructural changes of skeletal muscle only account for a small part of muscle fiber. In addition, for human experiments, due to the limitations of experimental methods, many deep injured muscles are not easy to biopsy. Therefore, some ultrastructural changes of muscle are often ignored in this field, which leads to different experimental results. In order to find the exact evidence and mark of Amy's morphology, it is necessary to conduct in-depth research in this field.In recent ten years, more and more attention has been paid to the biochemical changes during exercise muscle load and recovery period, which is sensitive and accurate indirect evidence. The biochemical indicators of muscle injury mainly include the increase of serum enzyme activity, especially the activity of creatine kinase; the increase of serum myoglobin (MB), and the increase of muscle protein conversion and urinary 3-methylhistidine excretion.


## 3. Protective Effect of Branched-Chain Amino Acids on Muscle Injury after Endurance Training

### 3.1. Composition and Function of Branched-Chain Amino Acids

Branched-chain amino acid is an organic compound containing basic amino acids and the acid Clostridium. It is the basic material of protein molecules. Protein is the basis of all tissues of the body and plays a decisive role in life phenomena and life processes. Protein is composed of a variety of amino acids through skin bonds, which is a phthalic acid amide bond connecting amino acid units. Incomplete protein metabolism and dysfunction are often caused by the lack of essential amino acids [11]. The protein in food enters the human body through the intestines and stomach.The most commonly used method of measuring maximum oxygen uptake is to perform a limit test in a laboratory. In order to allow the subjects to reach the maximum oxygen uptake, the test program adopts an incremental load method in the laboratory. The test method of respiratory function during exercise is a breath-by-breath analysis method to reach its maximum effort and to reach the maximum oxygen uptake in a specific time. There are differences between male and female athletes in their physiological structures, as well as differences in mechanistic response, effect results, and injury frequency. According to gender, we further subdivided the distribution of injury positions of high-level competitive fitness athletes, identified the areas with higher self-injury rates of male and female athletes, analyzed their characteristics, and improved the athletes’ resistance to injury, as shown in Figure2.Figure 2
Our country’s high-level competitions, health, and beauty, male and female athletes, and the distribution of the main sports injury positions.Its absorption process is first decomposed into different amino acids by various enzymes and then transported to various organs of the body for protein synthesis. Therefore, amino acids are essential substances for the human body. Food containing more amino acids not only has high nutritional value but also is easy to digest and absorb and participates in human energy metabolism, as shown in Figure3.Figure 3
Examples of related head and neck models.With the emergence of lactic acid threshold, the reason for the corresponding changes in ventilation is as follows: with the increase of exercise intensity, when the energy produced by aerobic metabolism cannot meet the oxygen demand of human exercise, the proportion of glycolysis energy supply gradually increases, and its by-products lead to increased blood lactic acid concentration. At this time, the body uses the bicarbonate buffer system in order to buffer lactic acid and produces sodium lactate and carbonic acid, resulting in an increase in carbon dioxide production. Observation and statistical results of muscle histochemical staining and fluorescent labeling can indicate that a certain degree of damage and loss of muscles occurs after fast downhill running, which is more serious on the day after exercise, there is an obvious recovery on the 4th day after exercise, and some muscle fibers are overrecovered on the day after exercise. There is hyperplasia performance after slow downhill running and uphill running, the muscles have no obvious damage or loss, or the damage and loss are very slight, as shown in Figures3 and 4.Figure 4
Comparison of changes in muscle cytoskeleton proteins after the initial and repeated exercises in each group.Amino acid is one of the most important elements in life, and it is widely used in medicine, food, and health care. In recent years, great progress has been made in physiology, pharmacology, and medicine. It is of great significance to study the synthesis of amino acids and their derivatives. The protection of amino acids is very important. This step has laid a solid foundation for the synthesis of necessary intermediates and has a decisive significance for the study of skin synthesis.


### 3.2. Catabolism Mechanism of Branched-Chain Amino Acids

In kinesiology, the ventilation threshold refers to the inflection point at which the increase in ventilation volume during exercise is faster than the increase in oxygen uptake. A person’s ventilatory threshold reflects the level of endurance and lactic acid accumulation. As exercise intensity increases, breathing becomes faster, more stable, and faster. When the breathing volume exceeds the normal ventilation volume, then the ventilation threshold is reached.BCAAs, including leucine, isoleucine, and valine, are essential amino acids for the human body. Food is the only source of BCAAs. The body maintains the level of BCAAs mainly by regulating the catabolism of BCAAs. BCAAs are the main energy supply amino acid and the only amino acid metabolized outside the liver. Leucine is the only ketogenic amino acid, isoleucine is a glycogen and ketogenic amino acid, vand aline is a glycogen amino acid. Although the molecular basis and regulatory mechanism of BCAAs uptake are still unclear, its downstream activation pathway is mainly through L-amino acid transporter and bidirectional transport of L-glutamine and L-leucine. Leucine, isoleucine, and valine are decomposed to produce corresponding ortho keto-iso-acetic acid, ortho keto-1-methylvaleric acid, and ortho keto-isovaleric acid, referred to as branched keto acids. Under the catalysis of mitochondrial branched-chain keto dehydrogenase complex, branched-chain keto acid can irreversibly oxidize decarboxylate to acetyl coenzyme A and succinyl coenzyme A and enter the tricarboxylic acid cycle. Reduced nicotinamide adenine dinucleotides enter the respiratory chain from the tricarboxylic acid cycle to participate in electron transport and finally generate ATP, as shown in Figure5:(1)
Regulation of enzyme activity [12]: feedback inhibition and feedback inhibition play an important role in the regulation of amino acid synthesis. Corynebacterium glutamicum can precisely and precisely regulate the synthesis of branched-chain amino acids through the combined action of complex feedback inhibition and feedback inhibition, thus maintaining the balance of branched-chain amino acids. Threonine deaminase was only inhibited by L-Ile, but not by valine and leucine. When L-Ile was insufficient, threonine deaminase activity was higher. On the premise of high affinity for α - ketobutyric acid, the synthesis rate of L-Ile in cells is much higher than that of other branched-chain amino acids; when the content of L-Ile in cells increases, the activity of threonine deaminase decreases, and the intracellular ketones decrease. Due to feedback inhibition, when the content of branched-chain amino acids reaches the demand, the inhibited branched-chain amino acids will be fed back, and then the synthesis of branched-chain amino acids will be reduced. The advantages of using cross-linking technology to detect protein interactions are as follows: it can detect weak interactions; it can detect transient interactions with different proteins at different stages of a dynamic process, such as glycosylation; linking reagents and cross-linking can occur in vivo.(2)
Gene regulation [13]: there are many regulatory mechanisms of gene expression, including transcriptional regulation, attenuation, carbon metabolism inhibition, and global regulatory factor expression regulation.Figure 5
Network diagram of the interaction of sudden variants of different proteins.


### 3.3. Physiological Function of Branched-Chain Amino Acids

BCAAs play an important role in physiology. Firstly, BCAAs are not only important raw materials for protein synthesis in vivo but also involved in the synthesis of sterols, ketones, and grapes. Secondly, BCAAs are the most important energy supply amino acid in aircraft, and they are an important energy substance. They can provide energy to the body through a series of biochemical reactions. Thirdly, BCAAs, especially leucine, are important signal molecules. They can activate the mTOR signaling pathway and promote protein synthesis, cell metabolism, cell growth, autophagy, neurotransmitter synthesis, carbohydrate utilization, and lipid metabolism. Therefore, BCAAs are essential to maintain the normal growth and function of cells and organs. Finally, BCAAs play an important role in mRNA translation. BCAAs, especially leucine, can enhance signal transduction at the beginning of mRNA translation. BCAAs can activate mTOR by phosphorylating its downstream effectors S6K1 and 4E BP1 and then act on eukaryotic initiation factor eif4f to enhance the stability of mRNA; BCAAs can also act on eIF2 · GTP · met-tRNAiMet in an unknown way, promoting the formation of a complex with ribosomal protein S6, thus promoting the initiation of mRNA translation.


### 3.4. Biosynthesis Pathway of Branched-Chain Amino Acids

Branched-chain amino acids include Ile, Leu, and Val, and their biosynthesis pathway only exists in plants and microorganisms [14]. The synthesis of L-Ile begins with aspartic acid and is catalyzed by a series of enzymes. Using pyruvic acid as a precursor, l-leu and L-Val were synthesized by a series of enzymes. In the biosynthesis of branched-chain amino acids, aspartic acid and threonine are two intermediate amino acid products, while lysine and methionine are two by-products of the bypass pathway. Among the enzymes involved in the biosynthesis of branched-chain amino acids, acetyl hydroxyl synthase, acetyl lactate isomerase, dihydroxy acid dehydratase, and branched-chain amino acid transaminase are the common enzymes in the biosynthesis of branched-chain amino acids. At present, there are few reports about BCAA in Bacillus. The research on the regulation of BCAA synthesis and metabolism mainly focuses on Escherichia coli and Corynebacterium glutamicum.


### 3.5. Protective Mechanism of Branched-Chain Amino Acids on Muscle Injury

Aerobic capacity is the most basic ability for athletes and the general population. It reflects an individual’s health level and is an important indicator for evaluating athletic ability. Therefore, it is also a hot spot for scholars at home and abroad. Among the indicators for assessing aerobic capacity, the maximum oxygen uptake is an important indicator for evaluating cardiorespiratory endurance, and the maximum oxygen uptake and ventilation threshold are the basis for formulating exercise intensity and are the physiological indicators for athlete selection.It is proved that branched-chain amino acids play an important role in the regulation of myocardial ischemia, blood pressure, and myocardial ischemia. In order to protect the athletes from myocardial injury, it can reduce myocardial injury by taking calcium [15]. Supplement of branched-chain amino acids in endurance training can reduce serum creatine poisoning. The simulation result is compared with the experimental result curve of Kerrigan et al. The simulation curve is basically located in the experimental channel, and the limit load is in good agreement with the experimental result. The displacement of the femur when it reaches the ultimate load is different from the experimental results, which is caused by the different ages of the experimental samples, as shown in Figures 6 and 7.Figure 6
Femur dynamic three-point bending (collision force-displacement).Figure 7
Fibula dynamic three-point bending (collision force-displacement).Supplementation of branched-chain amino acids [16] can reduce muscle injury associated with endurance exercise. It is found that exercise can promote the oxidation of branched-chain amino acids and increase the demand for branched-chain amino acids. Supplement of the branched-chain [17] nitrogen acid before and after exercise can reduce muscle injury caused by exercise and improve protein synthesis.


## 3.1. Composition and Function of Branched-Chain Amino Acids

Branched-chain amino acid is an organic compound containing basic amino acids and the acid Clostridium. It is the basic material of protein molecules. Protein is the basis of all tissues of the body and plays a decisive role in life phenomena and life processes. Protein is composed of a variety of amino acids through skin bonds, which is a phthalic acid amide bond connecting amino acid units. Incomplete protein metabolism and dysfunction are often caused by the lack of essential amino acids [11]. The protein in food enters the human body through the intestines and stomach.The most commonly used method of measuring maximum oxygen uptake is to perform a limit test in a laboratory. In order to allow the subjects to reach the maximum oxygen uptake, the test program adopts an incremental load method in the laboratory. The test method of respiratory function during exercise is a breath-by-breath analysis method to reach its maximum effort and to reach the maximum oxygen uptake in a specific time. There are differences between male and female athletes in their physiological structures, as well as differences in mechanistic response, effect results, and injury frequency. According to gender, we further subdivided the distribution of injury positions of high-level competitive fitness athletes, identified the areas with higher self-injury rates of male and female athletes, analyzed their characteristics, and improved the athletes’ resistance to injury, as shown in Figure2.Figure 2
Our country’s high-level competitions, health, and beauty, male and female athletes, and the distribution of the main sports injury positions.Its absorption process is first decomposed into different amino acids by various enzymes and then transported to various organs of the body for protein synthesis. Therefore, amino acids are essential substances for the human body. Food containing more amino acids not only has high nutritional value but also is easy to digest and absorb and participates in human energy metabolism, as shown in Figure3.Figure 3
Examples of related head and neck models.With the emergence of lactic acid threshold, the reason for the corresponding changes in ventilation is as follows: with the increase of exercise intensity, when the energy produced by aerobic metabolism cannot meet the oxygen demand of human exercise, the proportion of glycolysis energy supply gradually increases, and its by-products lead to increased blood lactic acid concentration. At this time, the body uses the bicarbonate buffer system in order to buffer lactic acid and produces sodium lactate and carbonic acid, resulting in an increase in carbon dioxide production. Observation and statistical results of muscle histochemical staining and fluorescent labeling can indicate that a certain degree of damage and loss of muscles occurs after fast downhill running, which is more serious on the day after exercise, there is an obvious recovery on the 4th day after exercise, and some muscle fibers are overrecovered on the day after exercise. There is hyperplasia performance after slow downhill running and uphill running, the muscles have no obvious damage or loss, or the damage and loss are very slight, as shown in Figures3 and 4.Figure 4
Comparison of changes in muscle cytoskeleton proteins after the initial and repeated exercises in each group.Amino acid is one of the most important elements in life, and it is widely used in medicine, food, and health care. In recent years, great progress has been made in physiology, pharmacology, and medicine. It is of great significance to study the synthesis of amino acids and their derivatives. The protection of amino acids is very important. This step has laid a solid foundation for the synthesis of necessary intermediates and has a decisive significance for the study of skin synthesis.


## 3.2. Catabolism Mechanism of Branched-Chain Amino Acids

In kinesiology, the ventilation threshold refers to the inflection point at which the increase in ventilation volume during exercise is faster than the increase in oxygen uptake. A person’s ventilatory threshold reflects the level of endurance and lactic acid accumulation. As exercise intensity increases, breathing becomes faster, more stable, and faster. When the breathing volume exceeds the normal ventilation volume, then the ventilation threshold is reached.BCAAs, including leucine, isoleucine, and valine, are essential amino acids for the human body. Food is the only source of BCAAs. The body maintains the level of BCAAs mainly by regulating the catabolism of BCAAs. BCAAs are the main energy supply amino acid and the only amino acid metabolized outside the liver. Leucine is the only ketogenic amino acid, isoleucine is a glycogen and ketogenic amino acid, vand aline is a glycogen amino acid. Although the molecular basis and regulatory mechanism of BCAAs uptake are still unclear, its downstream activation pathway is mainly through L-amino acid transporter and bidirectional transport of L-glutamine and L-leucine. Leucine, isoleucine, and valine are decomposed to produce corresponding ortho keto-iso-acetic acid, ortho keto-1-methylvaleric acid, and ortho keto-isovaleric acid, referred to as branched keto acids. Under the catalysis of mitochondrial branched-chain keto dehydrogenase complex, branched-chain keto acid can irreversibly oxidize decarboxylate to acetyl coenzyme A and succinyl coenzyme A and enter the tricarboxylic acid cycle. Reduced nicotinamide adenine dinucleotides enter the respiratory chain from the tricarboxylic acid cycle to participate in electron transport and finally generate ATP, as shown in Figure5:(1)
Regulation of enzyme activity [12]: feedback inhibition and feedback inhibition play an important role in the regulation of amino acid synthesis. Corynebacterium glutamicum can precisely and precisely regulate the synthesis of branched-chain amino acids through the combined action of complex feedback inhibition and feedback inhibition, thus maintaining the balance of branched-chain amino acids. Threonine deaminase was only inhibited by L-Ile, but not by valine and leucine. When L-Ile was insufficient, threonine deaminase activity was higher. On the premise of high affinity for α - ketobutyric acid, the synthesis rate of L-Ile in cells is much higher than that of other branched-chain amino acids; when the content of L-Ile in cells increases, the activity of threonine deaminase decreases, and the intracellular ketones decrease. Due to feedback inhibition, when the content of branched-chain amino acids reaches the demand, the inhibited branched-chain amino acids will be fed back, and then the synthesis of branched-chain amino acids will be reduced. The advantages of using cross-linking technology to detect protein interactions are as follows: it can detect weak interactions; it can detect transient interactions with different proteins at different stages of a dynamic process, such as glycosylation; linking reagents and cross-linking can occur in vivo.(2)
Gene regulation [13]: there are many regulatory mechanisms of gene expression, including transcriptional regulation, attenuation, carbon metabolism inhibition, and global regulatory factor expression regulation.Figure 5
Network diagram of the interaction of sudden variants of different proteins.


## 3.3. Physiological Function of Branched-Chain Amino Acids

BCAAs play an important role in physiology. Firstly, BCAAs are not only important raw materials for protein synthesis in vivo but also involved in the synthesis of sterols, ketones, and grapes. Secondly, BCAAs are the most important energy supply amino acid in aircraft, and they are an important energy substance. They can provide energy to the body through a series of biochemical reactions. Thirdly, BCAAs, especially leucine, are important signal molecules. They can activate the mTOR signaling pathway and promote protein synthesis, cell metabolism, cell growth, autophagy, neurotransmitter synthesis, carbohydrate utilization, and lipid metabolism. Therefore, BCAAs are essential to maintain the normal growth and function of cells and organs. Finally, BCAAs play an important role in mRNA translation. BCAAs, especially leucine, can enhance signal transduction at the beginning of mRNA translation. BCAAs can activate mTOR by phosphorylating its downstream effectors S6K1 and 4E BP1 and then act on eukaryotic initiation factor eif4f to enhance the stability of mRNA; BCAAs can also act on eIF2 · GTP · met-tRNAiMet in an unknown way, promoting the formation of a complex with ribosomal protein S6, thus promoting the initiation of mRNA translation.


## 3.4. Biosynthesis Pathway of Branched-Chain Amino Acids

Branched-chain amino acids include Ile, Leu, and Val, and their biosynthesis pathway only exists in plants and microorganisms [14]. The synthesis of L-Ile begins with aspartic acid and is catalyzed by a series of enzymes. Using pyruvic acid as a precursor, l-leu and L-Val were synthesized by a series of enzymes. In the biosynthesis of branched-chain amino acids, aspartic acid and threonine are two intermediate amino acid products, while lysine and methionine are two by-products of the bypass pathway. Among the enzymes involved in the biosynthesis of branched-chain amino acids, acetyl hydroxyl synthase, acetyl lactate isomerase, dihydroxy acid dehydratase, and branched-chain amino acid transaminase are the common enzymes in the biosynthesis of branched-chain amino acids. At present, there are few reports about BCAA in Bacillus. The research on the regulation of BCAA synthesis and metabolism mainly focuses on Escherichia coli and Corynebacterium glutamicum.


## 3.5. Protective Mechanism of Branched-Chain Amino Acids on Muscle Injury

Aerobic capacity is the most basic ability for athletes and the general population. It reflects an individual’s health level and is an important indicator for evaluating athletic ability. Therefore, it is also a hot spot for scholars at home and abroad. Among the indicators for assessing aerobic capacity, the maximum oxygen uptake is an important indicator for evaluating cardiorespiratory endurance, and the maximum oxygen uptake and ventilation threshold are the basis for formulating exercise intensity and are the physiological indicators for athlete selection.It is proved that branched-chain amino acids play an important role in the regulation of myocardial ischemia, blood pressure, and myocardial ischemia. In order to protect the athletes from myocardial injury, it can reduce myocardial injury by taking calcium [15]. Supplement of branched-chain amino acids in endurance training can reduce serum creatine poisoning. The simulation result is compared with the experimental result curve of Kerrigan et al. The simulation curve is basically located in the experimental channel, and the limit load is in good agreement with the experimental result. The displacement of the femur when it reaches the ultimate load is different from the experimental results, which is caused by the different ages of the experimental samples, as shown in Figures 6 and 7.Figure 6
Femur dynamic three-point bending (collision force-displacement).Figure 7
Fibula dynamic three-point bending (collision force-displacement).Supplementation of branched-chain amino acids [16] can reduce muscle injury associated with endurance exercise. It is found that exercise can promote the oxidation of branched-chain amino acids and increase the demand for branched-chain amino acids. Supplement of the branched-chain [17] nitrogen acid before and after exercise can reduce muscle injury caused by exercise and improve protein synthesis.


## 4. Results and Discussion

### 4.1. VAS Score of Muscle Injury

According to the VAS pain [18] score table, the degree of muscle injury of each athlete is counted, as shown, as shown in Figure 8.Figure 8
Pain analysis after global muscle injury.The higher the score is, the more serious the muscle injury is. According to the score, we can see that they mainly focus on 6–8 points, accounting for 44% of the total number of people. The second was 4–6, accounting for 34% of the total. It can be seen that the establishment of the muscle injury model is very successful, most people have a relatively large degree of muscle soreness, only a few people have reached the maximum [19] pain, very few people have an insufficient muscle injury, but the overall impact can be ignored. Muscle fatigue (muscle fatigue) is a decrease in muscle ability to work with repeated work (referring to “local muscle fatigue”). Motor muscle fatigue (exercise-induced muscle fatigue) refers to the movement caused by muscle maximum contraction force or maximum output power temporary decline in the physiological phenomenon and is the muscles in the process of contraction due to local muscle metabolism changes, morphological structure change, and nervous system function changes caused by a continuous, dynamic complex process.


### 4.2. Changes of Blood Indexes in the Intervention Group and Control Group after Endurance Exercise

After endurance training, the changes of blood glucose [20] and alanine aminotransferase in the intervention group were not very obvious, as shown in Figure 9.Figure 9
Changes of serum creatine kinase, alanine, and alanine aminotransferase in two groups.The activity of serum creatine kinase changed after endurance training, increased by 4.72 but began to decline after 1 hour, but it was still higher than that before the competition. In the control group, there was no significant change in blood glucose. Serum creatine kinase and alanine aminotransferase increased significantly after the exercise. Serum creatine kinase began to decrease after 1 hour, which was higher than that before exercise, but glutamic pyruvic transaminase decreased at 1 hour until lower than that before exercise, as shown in Table3.Table 3
Changes of blood glucose and lactate dehydrogenase in two groups.
QuietImmediately after exercise1 hour after exerciseIntervention groupALA257.6325.4296.6LD237.15240.0285.9Control groupALA294.7199.4220.5LD341.6285.17290.8The changes of alanine in the intervention group first increased and then decreased, reaching the peak at the end of the exercise. However, the content of LDH has been in the rising stage, even if the content of LDH [21] after exercise is higher than that before and after exercise. The content of alanine in the control group decreased significantly immediately after exercise and recovered to a part after 1 hour, but it was still lower than that before exercise. Compared with the intervention group, LDH showed a downward trend; that is, the LDH of athletes taking branched-chain amino acids had a significant upward trend.


### 4.3. Changes of Three Substances before and after Exercise and 2 Hours after Exercise

After receiving the designed endurance training, there was no significant change in alanine aminotransferase in the control group 2 hours after exercise, as shown in Figure10.Figure 10
Changes of serum creatine kinase, lactate dehydrogenase, and alanine aminotransferase before and after endurance test in two groups.The contents of creatine kinase and lactate dehydrogenase in the control group were measured immediately after exercise and 2 hours after exercise. The results showed that the contents of creatine kinase [22] and lactate dehydrogenase increased significantly, as shown in Figure 11.Figure 11
Before and after tomographic images. (a) Raw tomographic image of the carpal bone. (b) Tomographic image after carpal threshold segmentation.
(a)(b)According to the nature of the CT image and the different CT values of the bones and soft tissues of the wrist, the segmentation is performed by setting the threshold range. First, select an appropriate threshold [23]. For example, if the CT value is too high, parts with thin bones or slightly lower density cannot be included, forming false holes or irregular fissures; too low will also include other structures at the edge of the bone in the imaging range and make the edges blurred, and some structural levels cannot be distinguished. But it should be adjusted appropriately according to the bone density, as shown in Figure 11.In the intervention group, the serum creatine kinase and lactate dehydrogenase were only measured immediately after exercise, which were significantly increased compared with those without exercise, but still lower than those in the control group. The level of creatine kinase in serum was also much lower than that in the control group at 2 hours after exercise.


### 4.4. Effect of Branched-Chain Amino Acids on Endurance of Aerobics Athletes

The endurance of the experimental group in the endurance test after taking BCAA is much higher than that of the control group and the people who receive any training. The longer the exercise time, the more energy consumption, the more effective the branched-chain amino acids supplement will be, as shown in Figure12.Figure 12
Effect of chain amino acids on the endurance of aerobics athletes.


## 4.1. VAS Score of Muscle Injury

According to the VAS pain [18] score table, the degree of muscle injury of each athlete is counted, as shown, as shown in Figure 8.Figure 8
Pain analysis after global muscle injury.The higher the score is, the more serious the muscle injury is. According to the score, we can see that they mainly focus on 6–8 points, accounting for 44% of the total number of people. The second was 4–6, accounting for 34% of the total. It can be seen that the establishment of the muscle injury model is very successful, most people have a relatively large degree of muscle soreness, only a few people have reached the maximum [19] pain, very few people have an insufficient muscle injury, but the overall impact can be ignored. Muscle fatigue (muscle fatigue) is a decrease in muscle ability to work with repeated work (referring to “local muscle fatigue”). Motor muscle fatigue (exercise-induced muscle fatigue) refers to the movement caused by muscle maximum contraction force or maximum output power temporary decline in the physiological phenomenon and is the muscles in the process of contraction due to local muscle metabolism changes, morphological structure change, and nervous system function changes caused by a continuous, dynamic complex process.


## 4.2. Changes of Blood Indexes in the Intervention Group and Control Group after Endurance Exercise

After endurance training, the changes of blood glucose [20] and alanine aminotransferase in the intervention group were not very obvious, as shown in Figure 9.Figure 9
Changes of serum creatine kinase, alanine, and alanine aminotransferase in two groups.The activity of serum creatine kinase changed after endurance training, increased by 4.72 but began to decline after 1 hour, but it was still higher than that before the competition. In the control group, there was no significant change in blood glucose. Serum creatine kinase and alanine aminotransferase increased significantly after the exercise. Serum creatine kinase began to decrease after 1 hour, which was higher than that before exercise, but glutamic pyruvic transaminase decreased at 1 hour until lower than that before exercise, as shown in Table3.Table 3
Changes of blood glucose and lactate dehydrogenase in two groups.
QuietImmediately after exercise1 hour after exerciseIntervention groupALA257.6325.4296.6LD237.15240.0285.9Control groupALA294.7199.4220.5LD341.6285.17290.8The changes of alanine in the intervention group first increased and then decreased, reaching the peak at the end of the exercise. However, the content of LDH has been in the rising stage, even if the content of LDH [21] after exercise is higher than that before and after exercise. The content of alanine in the control group decreased significantly immediately after exercise and recovered to a part after 1 hour, but it was still lower than that before exercise. Compared with the intervention group, LDH showed a downward trend; that is, the LDH of athletes taking branched-chain amino acids had a significant upward trend.


## 4.3. Changes of Three Substances before and after Exercise and 2 Hours after Exercise

After receiving the designed endurance training, there was no significant change in alanine aminotransferase in the control group 2 hours after exercise, as shown in Figure10.Figure 10
Changes of serum creatine kinase, lactate dehydrogenase, and alanine aminotransferase before and after endurance test in two groups.The contents of creatine kinase and lactate dehydrogenase in the control group were measured immediately after exercise and 2 hours after exercise. The results showed that the contents of creatine kinase [22] and lactate dehydrogenase increased significantly, as shown in Figure 11.Figure 11
Before and after tomographic images. (a) Raw tomographic image of the carpal bone. (b) Tomographic image after carpal threshold segmentation.
(a)(b)According to the nature of the CT image and the different CT values of the bones and soft tissues of the wrist, the segmentation is performed by setting the threshold range. First, select an appropriate threshold [23]. For example, if the CT value is too high, parts with thin bones or slightly lower density cannot be included, forming false holes or irregular fissures; too low will also include other structures at the edge of the bone in the imaging range and make the edges blurred, and some structural levels cannot be distinguished. But it should be adjusted appropriately according to the bone density, as shown in Figure 11.In the intervention group, the serum creatine kinase and lactate dehydrogenase were only measured immediately after exercise, which were significantly increased compared with those without exercise, but still lower than those in the control group. The level of creatine kinase in serum was also much lower than that in the control group at 2 hours after exercise.


## 4.4. Effect of Branched-Chain Amino Acids on Endurance of Aerobics Athletes

The endurance of the experimental group in the endurance test after taking BCAA is much higher than that of the control group and the people who receive any training. The longer the exercise time, the more energy consumption, the more effective the branched-chain amino acids supplement will be, as shown in Figure12.Figure 12
Effect of chain amino acids on the endurance of aerobics athletes.


## 5. Conclusion

For people with abundant fast-twitch fibers, such as sprinters, the ratio of fast-twitch fibers is higher than that of slow-twitch fibers, because sprinters need strong explosive power, and the fast-twitch fibers have a relatively large diameter and can provide great power output. Therefore, sprinters tend to have thicker lower limbs and a high proportion of fast-twitch fibers. Competitive aerobics athletes must have the quality of coordination, flexibility, and sports tolerance. Complex gymnastics is a challenge for athletes. A little inattention will cause muscles to pull up, which will lead to an instant collapse of the overall body coordination. In order to avoid the occurrence of this kind of event, this paper puts forward the protective effect of branched-chain amino acids on muscle injury of aerobics athletes after endurance exercise. According to the experimental results, the measurement results after 1 hour of exercise are the same as those of 2 hours. Therefore, after endurance training, the blood glucose content of the intervention group gradually decreased and returned to the original level after 2 hours of exercise, while the control group was lower than the level of exercise after exercise and 2 hours later; the content of alanine in both groups showed a downward trend after exercise, and the decrease was more after 2 hours; the blood creatine kinase in the intervention group was measured immediately after exercise In the intervention group, lactate dehydrogenase increased rapidly at 2 hours after exercise, while that in the control group increased immediately after exercise; the content of alanine aminotransferase in the intervention group increased after exercise, but there was no significant change in the control group. Finally, it is found that the longer the exercise time is, the more effective the BCAA plays in protecting muscle injury. From the above experimental results, we found that branched-chain amino acids can be used as a drug to promote protein synthesis to repair muscle injury, which can reduce the pain caused by muscle injury, which is worthy of application for athletes in all walks of life who are troubled by muscle injury. The advantage of this paper is to discuss that amino acids based on CT images can play a protective role in aerobics athletes’ muscle damage after endurance exercise, and CT can be well used to protect muscle damage, but the experiment in this paper is not so perfect, in the data collection. There are still many shortcomings.



---

*Source: 5961267-2022-03-19.xml*