# Modeling and Analysis of Football Players’ Specific Physical Ability Based on Training Evaluation Index

Authors: Yuanhua Li; Shishan Zeng
Journal: Security and Communication Networks
 (2021)

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## Abstract

In order to accurately and efficiently evaluate the effect of special physical training for football players, modeling and analysis of evaluation indexes of special physical training for football players were mainly carried out. This paper analyzes the construction principle of the evaluation index system of football players’ special physical training, determines the evaluation primary index system, and constructs the evaluation index system of football players’ special physical training through comparison and screening. On this basis, the analytic hierarchy process is used to calculate the weight of the evaluation index, according to the weight calculation results of the evaluation index modeling using multilevel fuzzy comprehensive evaluation so as to get the evaluation results of the special physical training of football players. The experimental results show that the evaluation results of football players’ special physical training are consistent with the expert evaluation results, and the evaluation time is short, which can realize the accurate and efficient evaluation of football players’ special physical training effect.


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## Body

## 1. Introduction

It can be seen from the competitions of various sports that the athletes or sports teams with superior skills cannot win the final victory, which is often due to the lack of physical ability, especially when the level is extremely close [1]. According to the classic event group training theory, football belongs to the same field antagonistic event dominated by skills, and the dominant factor determining its competitive level is skills [2]. With the continuous improvement and development of the level of football, the leading factors that constitute the competitive ability of football are also changing. Therefore, Mr. Tian Maijiu has made some adjustments and improvements to the classic event group theory. In the latest event group theory, he proposed that the winning factors of modern football events have gradually transited from the past single factor to the era of composite factors. Its leading factors include physical fitness, skills, and tactics [3]. The specificity and diversity of the competitive ability of football require that athletes must have the excellent special physical ability in order to give full play to their competitive ability, show a high competitive level, win over opponents, and achieve excellent results [4].Nowadays, the competition in high-level professional football matches is becoming more and more intense, and the antagonism is becoming stronger and stronger, which requires the football players to have a good special physical ability. Especially when the two teams have the same strength and the skills and tactics are indistinguishable, the physical ability of the players is often the decisive factor of whether the team can take the initiative in the competition and win the match [5]. Therefore, professional football teams attach great importance to the physical training of players [6]. Football players with excellent physical condition must be in accordance with the scientific theory of the special physical training, adopt reasonable and effective means of training, and combine with the project characteristics and physical energy laws to establish a scientific evaluation index system, and when making an assessment to the athletes’ physical condition and diagnosis, scientific monitoring should be done [7]. The increase in grid resources is planned in advance to ensure the reliability of the power supply. This is done by performing reliability studies at the planning stage to calculate reliability indicators to ensure that the required level of reliability is met. Reference [8] in the framework of the Monte Carlo simulation process proposed a state classification method of power system reliability indicators based on the combination of multilabel radial basis function (MLRBF) network and importance sampling (IS). In the process of physical training, scientific physical training is an important subject to adjust and control physical load intensity in real time, accurately and effectively according to the internal physiological load of the human body, so that it meets the scheduled target of the training plan. Reference [9] designed an intelligent physical fitness monitoring system based on the internet of things technology in view of the current popularity of smartphones and the demand for athlete training monitoring.In fact, mobile computing is how to provide high-quality information services (information storage, query, calculation, etc.) to mobile users distributed in different locations (including laptops, PDA, mobile phones, pagers, etc.). The designed database system can provide data service to all kinds of user terminal equipment safely, quickly, and effectively. It is very necessary to use sensors to carry out modeling and analysis of the evaluation index of special physical training for football players [10–13].Therefore, according to the above analysis, this paper mainly carries on the modeling analysis of the evaluation index of football players’ special physical training.The remainder of this paper is organized as follows. Section2 introduces the modeling of the evaluation index of special physical training for football players. Section 3 discusses experimental design and result analysis. Section 4 presents the conclusions of the study.


## 2. Modeling of Evaluation Index of Special Physical Training for Football Players

### 2.1. Principles of Evaluation Index System Construction

The main basis for the selection of test items in this research is that they are representative and able to reflect the characteristics of football based on the principle of measuring the three characteristics of effectiveness, reliability, and objectiveness. The method is simple and feasible. The result can be expressed by quantity, and the original signs on the site can be used as much as possible. In line with its own characteristics, the test indicators adopted may be slightly different from those commonly used at home and abroad, but they can effectively reflect the specific physical training level of football players [14]. For the complex system of physical fitness, the state and change of the system cannot be described simply by a few indexes at present, but a series of indexes should be used to form an organic whole, and the development of the system can be described by establishing a physical fitness index model. Therefore, the following principles should be followed when formulating the evaluation index system:


#### 2.1.1. Scientific Principle

The index system must be established on the basis of science; the concept of the index must be clear; and the use of a certain scientific connotation can measure and reflect the current situation and development trend of the structure and function of the physical energy complex system. The scientificity of the physical fitness index is first shown as accuracy and objectivity, that is, it can objectively reflect the actual situation of the physical fitness level of football players, and it can essentially reflect the basic characteristics of the physical fitness of football players. Second, it is manifested in the rationality of the evaluation index system, that is, the evaluation should be carried out under the conditions of fairness and reasonableness, and the conditions of nonequivalence of the evaluation objects with different physical conditions are transformed into equivalent conditions [15].


#### 2.1.2. Operability Principle

One of the basic characteristics of the index is to link statistical theory with the practical operation, so is the construction of the physical fitness index system. It should not only be based on theoretical analysis but also consider the statistical operability and the feasibility of practical data support. Indicators should be set using available information as much as possible. In the actual survey, the index data is easy to be collected through statistical data, sample survey, or typical survey or directly obtained from the relevant departments (such as scientific research institutes). Those unobservable indicators, or those that can be measured in theory but cannot be operated in practice, cannot be included in the evaluation index system [16]. At the same time, on the premise of ensuring the correct reflection of the physical level and assessment, we should strive to be simple, highlight the key points, have clear meaning, and be easy to access data.


#### 2.1.3. Principle of Relative Completeness

The concept of physical fitness has profound and rich connotations, which requires that the index system describing and carving the concept of physical fitness level has enough coverage to comprehensively and generically reflect all aspects of physical fitness level. That is, in the three links of subsystem division, theme setting of subsystem, and index selection under each theme, the basic elements of the physical level connotation should be reflected as comprehensively and generically as possible, and the main content should not be omitted. At the same time, completeness means that the information content of the comprehensive index system should be both necessary and sufficient, and it should be able to reflect the development status of physical fitness level in a more comprehensive way [17].


#### 2.1.4. Principle of Relative Independence

Indicators that describe the development status of complex systems often overlap among indicators. Although this is inevitable, relatively independent indicators should be selected as far as possible in the selection of indicators so as to increase the accuracy and scientificity of evaluation [18].


#### 2.1.5. The Principle of Objectivity

The index design should accord with the development law of physical fitness itself, focus on the main body of physical fitness, and can objectively reflect the contribution of physical fitness to the level of sports training. The meaning and statistical scope of each index in the physical fitness index system should be clarified to ensure the comparison of time and space. In order to ensure comparability, relative indexes should be used as much as possible, and absolute indexes should be used less.


#### 2.1.6. Functional Principles

According to the purpose of the study, the functions of the specific physical evaluation indexes of football players can be summarized as follows: description function, evaluation function, guidance function, monitoring function, and prediction function. When reflecting the state of physical fitness and its evaluation, emphasis should be placed on the selection of indicators with guiding function, monitoring function, and evaluation function. In particular, the evaluation index system has the function of “ruler” and “baton.” In particular, important overall indexes are involved, which directly affect the future direction of physical training and training input of football players [19].


#### 2.1.7. The Principle of Structural Hierarchy

The index system constructed at a certain level has a certain hierarchical structure. Under the overall index of physical fitness level, it is first divided into several subsystems; under each subsystem, there are several topics; and so on, until the basic statistical index at the bottom level. This multilevel structure is beneficial to reflect the correlation among indexes and the systematicness of the overall index system.


#### 2.1.8. The Principle of Simplicity

In the index system, typical indicators with strong representativeness should be selected for the theme to be expressed, and more information should be contained with fewer indicators as far as possible, avoiding the inclusion of indicators with similar meaning, repetition, strong correlation, or exportable and making the index system simple and easy to use [20].


### 2.2. Construction of Evaluation Index System

During the preliminary establishment of the evaluation index system of special physical training for football players, a large number of index systems related to physical evaluation were comprehensively collected, and the frontline coaches and experts were interviewed and then analyzed and studied. The indicators with little effect were preliminarily excluded, and several main objectives of evaluation, namely the first-level indicators, were determined. The first-level indexes should be determined according to the training objectives and requirements of the special physical training for football players and the main situation of the evaluation organization and implementation. All the conceivable indicators were listed as the secondary and tertiary indicators. After literature review and logical analysis of all the listed indicators, the preliminary evaluation index system of special physical training for football players was finally determined [21].In order to make the established index system more direct, the evaluation is easier to operate and avoid the time-consuming of too many test items, which will bring difficulties to the test and calculation, thus affecting its promotion and application [22]. Therefore, this research uses the Delphi method to study 440 domestic and foreign coaches, senior coaches, team coaches, experts, and scholars of professional levels including coaches and professors of national teams, professional sports teams, and Sanda professional sports teams. Through two rounds of expert questionnaires, the 85% concentration index was included in the standard for assessment. A statistical table on the candidates, number, and percentage composition of Delphi experts is shown in Table 1. The statistical table of the questionnaire recovery rate of Delphi method survey is shown in Table 2.Table 1
Delphi experts candidates, number, and composition of the percentage statistical table.
ExpertsExperts and scholarsA senior managerProfessional coachProfessional team coachThe number of percentage1261185913728.626.813.431.2Table 2
Statistical table of the questionnaire recovery rate of Delphi method survey.
RoundsSpecialistsReal answer numberFirst round440135Second round440438At the same time, considering the principles of economy, practicability, testability, and ease of measurement, the indicators that were more complex and difficult to test were replaced [23], and finally, the evaluation indicators for specific physical training of football players were obtained, as shown in Table 3.Table 3
Evaluation index system of special physical training for football players.
Level indicatorsSecondary indicatorsLevel 3 indicatorsBody form (A1)Weight index (B1)Body fat percentage (C1)Nutritional index (B2)Ketone index (C2)Physical function (A2)Physiological function (B3)Maximum oxygen uptake (C3)Restoration (B4)Serum testosterone/cortisol (C4)Athletic quality (A3)Speed quality (B5)30 m run (C5)Strength quality (B6)Longitudinal jump touch height (C6)Endurance (B7)Yo-yo test(C7)Flexibility (B8)Groin flexibility test (C8)Sensitive quality (B9)Illinois run (C9)Quality of coordination (B10)Double skipping rope (C10)Technology (B11)Ball sensation (20 min running with the ball bouncing;C11)Mental ability (A4)Competition state anxiety (B12)State confidence (C12)Team attention (B13)Team member’s attention (C13)


### 2.3. Determination of Index Weights Based on Analytic Hierarchy Process

In the evaluation system of special physical training for football players, the contribution and importance of each index in the evaluation system are different, so it is necessary to determine the weight of each index to distinguish the relative importance of each index and objectively reflect the whole evaluation process [24]. As for the method of determining the weight, the commonly used methods are mean method, analytic hierarchy process, matrix algorithm, principal component analysis, and so on. This study mainly adopted the analytic hierarchy process to compare each index on the same level with each other and listed the comparison matrix [25] according to the relative importance grade table of T.L star, as shown in Table 4.Table 4
T.L star relative importance rating table.
Relative importanceDefine1As important3Slightly more important5Basically important or highly important7Really important9Absolutely vital2, 4, 6, 8The median value of importance between two neighborsThe corresponding scale value can be found in the grade table by comparing each index. IfA1 is equally important compared with A1, you can use 1; if A1 is slightly important compared with A2, you can use 5; if A1 is compared with A3, A3 over A1 is indeed important, and you can use 1/7, as shown in Table 5.Table 5
T.L star comparative judgment matrix.
CA1A2A3…AnA1A11A12A13…A1nA2A21A22A23…A2nA3A31A32A33…A3n………………AnAn1An2An3…AnnAfter the judgment matrix is obtained, the root method can be used to calculate the maximum eigenroot of the matrix and its corresponding eigenvector. The steps are as follows:(1)
Calculate the productB of elements in each row of judgment matrix Mi [26], and the result is expressed as follows:(1)Mi=∏i=1nbij,i=1,2,3,…,n.(2)
Calculate the NTH root of rowMi as w¯i, and the result is expressed as follows:(2)w¯i=nMi,i=1,2,3,…,n,wheren represents the matrix order.(3)
Normalize vectorW1,W2,W3,…,WnT, and the result can be expressed as follows:(3)wi=w¯i∑j=1nw¯j.(4)
Calculate the maximum eigenvalue of judgment matrixB, and the result is expressed as follows:(4)λmax=1n∑i=1nAw⌢iwi,whereAw⌢i is the i element of vector Aw⌢.Compared with other methods to determine the index weight coefficient, the greatest advantage of the analytic hierarchy process is that it can maintain the logical consistency of experts’ thoughts through consistency test. The so-called consistency of judgment thinking means that when experts judge the importance of indicators and when there are more than three indicators compared with each other, the judgments are consistent with each other, and no internal contradictory results will appear.In the consistency test of the judgment matrix, the deviation from the consistency indexCI and the average random consistency index RI need to be compared with the following calculation formula:(5)CI=λmax−nn−1.The value ofRI is shown in Table 6.Table 6
Values of RI.
n1234567891011121314RI000.520.891.121.241.361.411.461.491.521.541.561.58The calculation formula of random consistency indexCR is as follows:(6)CR=CIRI.WhenCR<0.1 is defined, the judgment matrix passes the consistency test; otherwise, the judgment matrix is modified until it is judged.The break matrix passes the consistency test. The output weight calculation result at this time is the final weight of football players’ specific physical training evaluation index.


### 2.4. Modeling and Analysis of Training Evaluation Indexes Based on Multilevel Fuzzy Comprehensive Evaluation

In a large complex system, there are many factors to be considered, and there are different levels among the factors. At this time, it is difficult to get the correct judgment result by applying the single-level fuzzy comprehensive evaluation model. Therefore, in this case, it is necessary to divide the set of evaluation factors into several categories according to a certain attribute, conduct a comprehensive evaluation of each category first, and then conduct a high-level comprehensive evaluation of all kinds of evaluation results between classes. In this way, the problem of multilevel fuzzy comprehensive evaluation arises. Therefore, this paper applies the multilevel fuzzy comprehensive evaluation method to the modeling process of soccer players’ specific physical training evaluation indicators so as to improve the modeling efficiency and accuracy.The main steps of modeling the evaluation index of special physical training for football players based on multilevel fuzzy comprehensive evaluation method are as follows:(1)
Establish the factor set of the evaluation object. If necessary, divide the factor setU=u1,u2,…,un into p subsets U=U1,U2,…,Up according to certain attributes.(2)
According to the importance of each evaluation factor, the analytic hierarchy process is adopted to determine the weight of each evaluation factor in each evaluation subfactor set and evaluation factor subset.(3)
The evaluation setV=v1,v2,…,vm of fuzzy comprehensive evaluation model is established, and the membership function of the lowest level evaluation factors is determined by the corresponding method.(4)
For each subfactor setUi=ui1,ui2,…,uin, make a fuzzy comprehensive evaluation and use the selected fuzzy operator to make fuzzy comprehensive evaluation.SetV=v1,v2,…,vm as the evaluation score set, and the formula for the relative weight distribution of each factor in Ui is as follows:(7)Ai=ai1,ai2,…,ain,whereaij>0,j=1,2,…,n and ai1+ai2+⋯+ain=1.IfRi is the single-factor evaluation matrix, the evaluation vector can be obtained as follows:(8)Bi=Ai∘Ri=bi1,bi2,…,bin,i=1,2,…,p.(5)
EachUi is regarded as a factor and denoted as W=U1,U2,…,Up, so W is also a factor set, and its single factor score evaluation matrix is as follows:(9)R=B1B2⋮Bp=b11b12⋯b1mb21b22⋯b2m⋮⋮⋱⋮bp1bp2⋯bpm.EachUi, as part of U, reflects some attribute of U and is assigned a weight of A=a1,a2,…,an according to their importance. Combining the evaluation matrix, the secondary evaluation vector can be obtained. The weighted summation of the various indicators yields a comprehensive score evaluation index system for football players’ specific physical training level indicators. Therefore, combining the multistage fuzzy comprehensive evaluation method has a better effect on the evaluation of football players’ specific physical training, and the description of the model is as follows:(10)U˜=B˜i=A˜i∘R˜i=A˜i∘A˜i1∘R˜i1A˜ij∘R˜ij,where B˜i=bi1,bi2,…bin represents the first-level fuzzy judgment set, A˜i=ai1,ai2,…,ain and A˜ij=ai1,ai2,…,ain represent the corresponding weight set, R˜ij represents the fuzzy relation matrix of dividing factors, and ∘ represents the fuzzy operation.The evaluation index modeling can be used to intuitively determine the scores of athletes in each index. The general quantitative model of the evaluation index of special physical training for football players is shown in Table7.Table 7
General quantitative model of evaluation indexes of specific physical training for football players.
IndicatorsUnitMinimum valueMaximum valueAverageStandard deviationBody fat percentage%7.417.410.632.6Ketone indexkg/cm354.05473.12406.6534.60Maximum oxygen uptakeml/kg.min54.5066.7060.576.01Serum testosterone/cortisolT/C (down %)183325.545.2530 m runs3.124.143.610.32Longitudinal jump touch heightcm496961.352.96Yo-yo testm/s16.5 ± 418.0 ± 617.5 ± 30.5 ± 4Groin flexibility testcm2.87.35.062.2Illinois runs12.3714.1113.010.52Double skipping ropeTime154130.466.36Ball sensation (20 min running with the ball bouncing)s4.325.134.630.36State confidence—233328.542.31Team member’s attention—368661.3817.22However, it is impossible to judge the level of individual and comprehensive physical fitness of football players scientifically without establishing the grading standards of individual and comprehensive physical fitness of football players. According to measurement and evaluation theory, grade evaluation usually adopts 5 evaluation methods, that is, excellent, good, pass, medium, and poor. The deviation method and percentile method can be used for the evaluation of 5. The latter has been widely used in foreign countries. In order to objectively reflect the differences in individual and comprehensive physical fitness of football players, this study established the grade evaluation standard table of specific physical training evaluation indexes for football players by using the percentage method, as shown in Table8.Table 8
Grade evaluation criteria table.
LevelPoor (%)Pass (%)Medium (%)Fine (%)Good (%)Indicators1010–1525–7575–90More than 90Theoretical percentage1015501510


## 2.1. Principles of Evaluation Index System Construction

The main basis for the selection of test items in this research is that they are representative and able to reflect the characteristics of football based on the principle of measuring the three characteristics of effectiveness, reliability, and objectiveness. The method is simple and feasible. The result can be expressed by quantity, and the original signs on the site can be used as much as possible. In line with its own characteristics, the test indicators adopted may be slightly different from those commonly used at home and abroad, but they can effectively reflect the specific physical training level of football players [14]. For the complex system of physical fitness, the state and change of the system cannot be described simply by a few indexes at present, but a series of indexes should be used to form an organic whole, and the development of the system can be described by establishing a physical fitness index model. Therefore, the following principles should be followed when formulating the evaluation index system:


### 2.1.1. Scientific Principle

The index system must be established on the basis of science; the concept of the index must be clear; and the use of a certain scientific connotation can measure and reflect the current situation and development trend of the structure and function of the physical energy complex system. The scientificity of the physical fitness index is first shown as accuracy and objectivity, that is, it can objectively reflect the actual situation of the physical fitness level of football players, and it can essentially reflect the basic characteristics of the physical fitness of football players. Second, it is manifested in the rationality of the evaluation index system, that is, the evaluation should be carried out under the conditions of fairness and reasonableness, and the conditions of nonequivalence of the evaluation objects with different physical conditions are transformed into equivalent conditions [15].


### 2.1.2. Operability Principle

One of the basic characteristics of the index is to link statistical theory with the practical operation, so is the construction of the physical fitness index system. It should not only be based on theoretical analysis but also consider the statistical operability and the feasibility of practical data support. Indicators should be set using available information as much as possible. In the actual survey, the index data is easy to be collected through statistical data, sample survey, or typical survey or directly obtained from the relevant departments (such as scientific research institutes). Those unobservable indicators, or those that can be measured in theory but cannot be operated in practice, cannot be included in the evaluation index system [16]. At the same time, on the premise of ensuring the correct reflection of the physical level and assessment, we should strive to be simple, highlight the key points, have clear meaning, and be easy to access data.


### 2.1.3. Principle of Relative Completeness

The concept of physical fitness has profound and rich connotations, which requires that the index system describing and carving the concept of physical fitness level has enough coverage to comprehensively and generically reflect all aspects of physical fitness level. That is, in the three links of subsystem division, theme setting of subsystem, and index selection under each theme, the basic elements of the physical level connotation should be reflected as comprehensively and generically as possible, and the main content should not be omitted. At the same time, completeness means that the information content of the comprehensive index system should be both necessary and sufficient, and it should be able to reflect the development status of physical fitness level in a more comprehensive way [17].


### 2.1.4. Principle of Relative Independence

Indicators that describe the development status of complex systems often overlap among indicators. Although this is inevitable, relatively independent indicators should be selected as far as possible in the selection of indicators so as to increase the accuracy and scientificity of evaluation [18].


### 2.1.5. The Principle of Objectivity

The index design should accord with the development law of physical fitness itself, focus on the main body of physical fitness, and can objectively reflect the contribution of physical fitness to the level of sports training. The meaning and statistical scope of each index in the physical fitness index system should be clarified to ensure the comparison of time and space. In order to ensure comparability, relative indexes should be used as much as possible, and absolute indexes should be used less.


### 2.1.6. Functional Principles

According to the purpose of the study, the functions of the specific physical evaluation indexes of football players can be summarized as follows: description function, evaluation function, guidance function, monitoring function, and prediction function. When reflecting the state of physical fitness and its evaluation, emphasis should be placed on the selection of indicators with guiding function, monitoring function, and evaluation function. In particular, the evaluation index system has the function of “ruler” and “baton.” In particular, important overall indexes are involved, which directly affect the future direction of physical training and training input of football players [19].


### 2.1.7. The Principle of Structural Hierarchy

The index system constructed at a certain level has a certain hierarchical structure. Under the overall index of physical fitness level, it is first divided into several subsystems; under each subsystem, there are several topics; and so on, until the basic statistical index at the bottom level. This multilevel structure is beneficial to reflect the correlation among indexes and the systematicness of the overall index system.


### 2.1.8. The Principle of Simplicity

In the index system, typical indicators with strong representativeness should be selected for the theme to be expressed, and more information should be contained with fewer indicators as far as possible, avoiding the inclusion of indicators with similar meaning, repetition, strong correlation, or exportable and making the index system simple and easy to use [20].


## 2.1.1. Scientific Principle

The index system must be established on the basis of science; the concept of the index must be clear; and the use of a certain scientific connotation can measure and reflect the current situation and development trend of the structure and function of the physical energy complex system. The scientificity of the physical fitness index is first shown as accuracy and objectivity, that is, it can objectively reflect the actual situation of the physical fitness level of football players, and it can essentially reflect the basic characteristics of the physical fitness of football players. Second, it is manifested in the rationality of the evaluation index system, that is, the evaluation should be carried out under the conditions of fairness and reasonableness, and the conditions of nonequivalence of the evaluation objects with different physical conditions are transformed into equivalent conditions [15].


## 2.1.2. Operability Principle

One of the basic characteristics of the index is to link statistical theory with the practical operation, so is the construction of the physical fitness index system. It should not only be based on theoretical analysis but also consider the statistical operability and the feasibility of practical data support. Indicators should be set using available information as much as possible. In the actual survey, the index data is easy to be collected through statistical data, sample survey, or typical survey or directly obtained from the relevant departments (such as scientific research institutes). Those unobservable indicators, or those that can be measured in theory but cannot be operated in practice, cannot be included in the evaluation index system [16]. At the same time, on the premise of ensuring the correct reflection of the physical level and assessment, we should strive to be simple, highlight the key points, have clear meaning, and be easy to access data.


## 2.1.3. Principle of Relative Completeness

The concept of physical fitness has profound and rich connotations, which requires that the index system describing and carving the concept of physical fitness level has enough coverage to comprehensively and generically reflect all aspects of physical fitness level. That is, in the three links of subsystem division, theme setting of subsystem, and index selection under each theme, the basic elements of the physical level connotation should be reflected as comprehensively and generically as possible, and the main content should not be omitted. At the same time, completeness means that the information content of the comprehensive index system should be both necessary and sufficient, and it should be able to reflect the development status of physical fitness level in a more comprehensive way [17].


## 2.1.4. Principle of Relative Independence

Indicators that describe the development status of complex systems often overlap among indicators. Although this is inevitable, relatively independent indicators should be selected as far as possible in the selection of indicators so as to increase the accuracy and scientificity of evaluation [18].


## 2.1.5. The Principle of Objectivity

The index design should accord with the development law of physical fitness itself, focus on the main body of physical fitness, and can objectively reflect the contribution of physical fitness to the level of sports training. The meaning and statistical scope of each index in the physical fitness index system should be clarified to ensure the comparison of time and space. In order to ensure comparability, relative indexes should be used as much as possible, and absolute indexes should be used less.


## 2.1.6. Functional Principles

According to the purpose of the study, the functions of the specific physical evaluation indexes of football players can be summarized as follows: description function, evaluation function, guidance function, monitoring function, and prediction function. When reflecting the state of physical fitness and its evaluation, emphasis should be placed on the selection of indicators with guiding function, monitoring function, and evaluation function. In particular, the evaluation index system has the function of “ruler” and “baton.” In particular, important overall indexes are involved, which directly affect the future direction of physical training and training input of football players [19].


## 2.1.7. The Principle of Structural Hierarchy

The index system constructed at a certain level has a certain hierarchical structure. Under the overall index of physical fitness level, it is first divided into several subsystems; under each subsystem, there are several topics; and so on, until the basic statistical index at the bottom level. This multilevel structure is beneficial to reflect the correlation among indexes and the systematicness of the overall index system.


## 2.1.8. The Principle of Simplicity

In the index system, typical indicators with strong representativeness should be selected for the theme to be expressed, and more information should be contained with fewer indicators as far as possible, avoiding the inclusion of indicators with similar meaning, repetition, strong correlation, or exportable and making the index system simple and easy to use [20].


## 2.2. Construction of Evaluation Index System

During the preliminary establishment of the evaluation index system of special physical training for football players, a large number of index systems related to physical evaluation were comprehensively collected, and the frontline coaches and experts were interviewed and then analyzed and studied. The indicators with little effect were preliminarily excluded, and several main objectives of evaluation, namely the first-level indicators, were determined. The first-level indexes should be determined according to the training objectives and requirements of the special physical training for football players and the main situation of the evaluation organization and implementation. All the conceivable indicators were listed as the secondary and tertiary indicators. After literature review and logical analysis of all the listed indicators, the preliminary evaluation index system of special physical training for football players was finally determined [21].In order to make the established index system more direct, the evaluation is easier to operate and avoid the time-consuming of too many test items, which will bring difficulties to the test and calculation, thus affecting its promotion and application [22]. Therefore, this research uses the Delphi method to study 440 domestic and foreign coaches, senior coaches, team coaches, experts, and scholars of professional levels including coaches and professors of national teams, professional sports teams, and Sanda professional sports teams. Through two rounds of expert questionnaires, the 85% concentration index was included in the standard for assessment. A statistical table on the candidates, number, and percentage composition of Delphi experts is shown in Table 1. The statistical table of the questionnaire recovery rate of Delphi method survey is shown in Table 2.Table 1
Delphi experts candidates, number, and composition of the percentage statistical table.
ExpertsExperts and scholarsA senior managerProfessional coachProfessional team coachThe number of percentage1261185913728.626.813.431.2Table 2
Statistical table of the questionnaire recovery rate of Delphi method survey.
RoundsSpecialistsReal answer numberFirst round440135Second round440438At the same time, considering the principles of economy, practicability, testability, and ease of measurement, the indicators that were more complex and difficult to test were replaced [23], and finally, the evaluation indicators for specific physical training of football players were obtained, as shown in Table 3.Table 3
Evaluation index system of special physical training for football players.
Level indicatorsSecondary indicatorsLevel 3 indicatorsBody form (A1)Weight index (B1)Body fat percentage (C1)Nutritional index (B2)Ketone index (C2)Physical function (A2)Physiological function (B3)Maximum oxygen uptake (C3)Restoration (B4)Serum testosterone/cortisol (C4)Athletic quality (A3)Speed quality (B5)30 m run (C5)Strength quality (B6)Longitudinal jump touch height (C6)Endurance (B7)Yo-yo test(C7)Flexibility (B8)Groin flexibility test (C8)Sensitive quality (B9)Illinois run (C9)Quality of coordination (B10)Double skipping rope (C10)Technology (B11)Ball sensation (20 min running with the ball bouncing;C11)Mental ability (A4)Competition state anxiety (B12)State confidence (C12)Team attention (B13)Team member’s attention (C13)


## 2.3. Determination of Index Weights Based on Analytic Hierarchy Process

In the evaluation system of special physical training for football players, the contribution and importance of each index in the evaluation system are different, so it is necessary to determine the weight of each index to distinguish the relative importance of each index and objectively reflect the whole evaluation process [24]. As for the method of determining the weight, the commonly used methods are mean method, analytic hierarchy process, matrix algorithm, principal component analysis, and so on. This study mainly adopted the analytic hierarchy process to compare each index on the same level with each other and listed the comparison matrix [25] according to the relative importance grade table of T.L star, as shown in Table 4.Table 4
T.L star relative importance rating table.
Relative importanceDefine1As important3Slightly more important5Basically important or highly important7Really important9Absolutely vital2, 4, 6, 8The median value of importance between two neighborsThe corresponding scale value can be found in the grade table by comparing each index. IfA1 is equally important compared with A1, you can use 1; if A1 is slightly important compared with A2, you can use 5; if A1 is compared with A3, A3 over A1 is indeed important, and you can use 1/7, as shown in Table 5.Table 5
T.L star comparative judgment matrix.
CA1A2A3…AnA1A11A12A13…A1nA2A21A22A23…A2nA3A31A32A33…A3n………………AnAn1An2An3…AnnAfter the judgment matrix is obtained, the root method can be used to calculate the maximum eigenroot of the matrix and its corresponding eigenvector. The steps are as follows:(1)
Calculate the productB of elements in each row of judgment matrix Mi [26], and the result is expressed as follows:(1)Mi=∏i=1nbij,i=1,2,3,…,n.(2)
Calculate the NTH root of rowMi as w¯i, and the result is expressed as follows:(2)w¯i=nMi,i=1,2,3,…,n,wheren represents the matrix order.(3)
Normalize vectorW1,W2,W3,…,WnT, and the result can be expressed as follows:(3)wi=w¯i∑j=1nw¯j.(4)
Calculate the maximum eigenvalue of judgment matrixB, and the result is expressed as follows:(4)λmax=1n∑i=1nAw⌢iwi,whereAw⌢i is the i element of vector Aw⌢.Compared with other methods to determine the index weight coefficient, the greatest advantage of the analytic hierarchy process is that it can maintain the logical consistency of experts’ thoughts through consistency test. The so-called consistency of judgment thinking means that when experts judge the importance of indicators and when there are more than three indicators compared with each other, the judgments are consistent with each other, and no internal contradictory results will appear.In the consistency test of the judgment matrix, the deviation from the consistency indexCI and the average random consistency index RI need to be compared with the following calculation formula:(5)CI=λmax−nn−1.The value ofRI is shown in Table 6.Table 6
Values of RI.
n1234567891011121314RI000.520.891.121.241.361.411.461.491.521.541.561.58The calculation formula of random consistency indexCR is as follows:(6)CR=CIRI.WhenCR<0.1 is defined, the judgment matrix passes the consistency test; otherwise, the judgment matrix is modified until it is judged.The break matrix passes the consistency test. The output weight calculation result at this time is the final weight of football players’ specific physical training evaluation index.


## 2.4. Modeling and Analysis of Training Evaluation Indexes Based on Multilevel Fuzzy Comprehensive Evaluation

In a large complex system, there are many factors to be considered, and there are different levels among the factors. At this time, it is difficult to get the correct judgment result by applying the single-level fuzzy comprehensive evaluation model. Therefore, in this case, it is necessary to divide the set of evaluation factors into several categories according to a certain attribute, conduct a comprehensive evaluation of each category first, and then conduct a high-level comprehensive evaluation of all kinds of evaluation results between classes. In this way, the problem of multilevel fuzzy comprehensive evaluation arises. Therefore, this paper applies the multilevel fuzzy comprehensive evaluation method to the modeling process of soccer players’ specific physical training evaluation indicators so as to improve the modeling efficiency and accuracy.The main steps of modeling the evaluation index of special physical training for football players based on multilevel fuzzy comprehensive evaluation method are as follows:(1)
Establish the factor set of the evaluation object. If necessary, divide the factor setU=u1,u2,…,un into p subsets U=U1,U2,…,Up according to certain attributes.(2)
According to the importance of each evaluation factor, the analytic hierarchy process is adopted to determine the weight of each evaluation factor in each evaluation subfactor set and evaluation factor subset.(3)
The evaluation setV=v1,v2,…,vm of fuzzy comprehensive evaluation model is established, and the membership function of the lowest level evaluation factors is determined by the corresponding method.(4)
For each subfactor setUi=ui1,ui2,…,uin, make a fuzzy comprehensive evaluation and use the selected fuzzy operator to make fuzzy comprehensive evaluation.SetV=v1,v2,…,vm as the evaluation score set, and the formula for the relative weight distribution of each factor in Ui is as follows:(7)Ai=ai1,ai2,…,ain,whereaij>0,j=1,2,…,n and ai1+ai2+⋯+ain=1.IfRi is the single-factor evaluation matrix, the evaluation vector can be obtained as follows:(8)Bi=Ai∘Ri=bi1,bi2,…,bin,i=1,2,…,p.(5)
EachUi is regarded as a factor and denoted as W=U1,U2,…,Up, so W is also a factor set, and its single factor score evaluation matrix is as follows:(9)R=B1B2⋮Bp=b11b12⋯b1mb21b22⋯b2m⋮⋮⋱⋮bp1bp2⋯bpm.EachUi, as part of U, reflects some attribute of U and is assigned a weight of A=a1,a2,…,an according to their importance. Combining the evaluation matrix, the secondary evaluation vector can be obtained. The weighted summation of the various indicators yields a comprehensive score evaluation index system for football players’ specific physical training level indicators. Therefore, combining the multistage fuzzy comprehensive evaluation method has a better effect on the evaluation of football players’ specific physical training, and the description of the model is as follows:(10)U˜=B˜i=A˜i∘R˜i=A˜i∘A˜i1∘R˜i1A˜ij∘R˜ij,where B˜i=bi1,bi2,…bin represents the first-level fuzzy judgment set, A˜i=ai1,ai2,…,ain and A˜ij=ai1,ai2,…,ain represent the corresponding weight set, R˜ij represents the fuzzy relation matrix of dividing factors, and ∘ represents the fuzzy operation.The evaluation index modeling can be used to intuitively determine the scores of athletes in each index. The general quantitative model of the evaluation index of special physical training for football players is shown in Table7.Table 7
General quantitative model of evaluation indexes of specific physical training for football players.
IndicatorsUnitMinimum valueMaximum valueAverageStandard deviationBody fat percentage%7.417.410.632.6Ketone indexkg/cm354.05473.12406.6534.60Maximum oxygen uptakeml/kg.min54.5066.7060.576.01Serum testosterone/cortisolT/C (down %)183325.545.2530 m runs3.124.143.610.32Longitudinal jump touch heightcm496961.352.96Yo-yo testm/s16.5 ± 418.0 ± 617.5 ± 30.5 ± 4Groin flexibility testcm2.87.35.062.2Illinois runs12.3714.1113.010.52Double skipping ropeTime154130.466.36Ball sensation (20 min running with the ball bouncing)s4.325.134.630.36State confidence—233328.542.31Team member’s attention—368661.3817.22However, it is impossible to judge the level of individual and comprehensive physical fitness of football players scientifically without establishing the grading standards of individual and comprehensive physical fitness of football players. According to measurement and evaluation theory, grade evaluation usually adopts 5 evaluation methods, that is, excellent, good, pass, medium, and poor. The deviation method and percentile method can be used for the evaluation of 5. The latter has been widely used in foreign countries. In order to objectively reflect the differences in individual and comprehensive physical fitness of football players, this study established the grade evaluation standard table of specific physical training evaluation indexes for football players by using the percentage method, as shown in Table8.Table 8
Grade evaluation criteria table.
LevelPoor (%)Pass (%)Medium (%)Fine (%)Good (%)Indicators1010–1525–7575–90More than 90Theoretical percentage1015501510


## 3. Experimental Design and Result Analysis

In order to verify the practical application effect of the modeling method of evaluation index of football players’ special physical training, it is necessary to carry out experimental tests. Taking 15 football players from a provincial team as experimental objects, the method in this paper is used to evaluate the effect of special physical training for football players.Among them, the weight calculation results of each index are shown in Table9.Table 9
Calculation results of the weight of evaluation index of special physical training for football players.
Level indicatorsWeightSecondary indicatorsLevel 3 indicatorsWeightBody shape0.13Weight indexBody fat percentage0.54Nutrition indexKetone index0.46Body0.20Physiological functionMaximum oxygen uptake0.51Resume functionSerum testosterone/cortisol0.49Exercise quality0.49The speed quality30 m run0.16Power qualityLongitudinal jump touch height0.14Endurance qualityYo-yo test0.18Flexible qualityGroin flexibility test0.12Sensitive qualityIllinois run0.12Coordinate qualityDouble skipping rope0.11TechnologyBall sensation (20 min running with the ball bouncing)0.17Mental ability0.18Competition state anxietyState confidence0.37Team attentionTeam member’s attention0.63According to the weight calculation results, the scores of three indexes in the evaluation index system of special physical training for football players can be obtained. The results are shown in Table10. The line graph results are shown in Figure 1.Table 10
Three-level index scores.
Athlete numberC1C2C3C4C5C6C7C8C9C10C11C12C1317.025.5210.27.842.42.82.522.161.561.762.897.412.626.485.5210.29.81.445.523.062.161.082.093.46.6611.3432.167.366.125.391.60.981.621.561.201.541.362.2210.7148.13.223.570.491.761.260.90.960.9602.892.226.3510.804.083.922.241.962.881.081.680.991.873.78.1968.643.226.635.391.281.822.160.841.81.212.384.4410.0873.245.988.169.313.22.523.241.441.922.093.45.9211.3487.025.987.565.881.281.681.980.481.81.210.852.226.93910.81.844.083.341.61.541.80.841.21.430.681.481.26109.182.767.140000.36000.442.740.740118.642.35.616.372.722.82.521.560.222.045.186.33.6127.561.382.556.370.961.961.80.721.82.22.554.447.56139.722.761.5300.961.40.90.61.560.222.045.186.3148.642.35.616.372.722.82.521.562.42.23.41.4812.61504.1403.921.121.542.160.61.21.211.022.960Figure 1
Three-level index scores.According to the different weights of the first-level indicators, the weighted scores of the first-level indicators of the athletes are calculated, and the weighted scores of all the first-level indicators are added and summed to obtain the comprehensive scores of the first-level indicators in the evaluation index system of special physical training for football players. The results are shown in Table11.Table 11
Grade I index scores.
Athlete numberPhysical qualityBodyExercise qualityMental abilityComposite scores11.633.617.883.616.7221.5647.723.2416.5231.242.34.832.3310.741.470.814.281.538.0951.401.66.222.1411.3661.542.45.632.6112.1871.203.498.733.1116.5381.602.694.191.6510.1391.641.54.540.498.17101.551.431.720.134.83111.722.585.992.2212.51121.161.785.882.1610.98131.620.313.762.077.76141.422.48.622.5314.97150.540.784.52.147.96According to the table formulated by the grade evaluation standard, the grade evaluation model of special physical training for football players can be established, and the evaluation results of special physical training for football players can be obtained. In order to more clearly compare the effects of different factors on grades, corresponding line charts are presented, as shown in Figure2.Figure 2
Grade I index scores.Wherein, in order to verify the effectiveness of the proposed method, the expert evaluation results are taken as a comparison, and the evaluation results of the expert evaluation results and the proposed method are shown in Tables12 and 13:Table 12
Expert evaluation results.
Athlete numberEvaluation results1Good2Good3Medium4Pass5Medium6Medium7Good8Medium9Medium10Poor11Medium12Medium13Medium14Good15PassTable 13
Evaluation results of this paper.
Athlete numberPhysical qualityBodyExercise qualityMental abilityComposite scores1MediumGoodGoodGoodGood2MediumGoodGoodGoodGood3PassMediumMediumMediumMedium4MediumPassMediumMediumPass5MediumMediumMediumMediumMedium6MediumMediumMediumGoodMedium7PassGoodGoodGoodGood8MediumGoodPassMediumMedium9GoodMediumMediumPassMedium10MediumMediumPoorMediumPoor11GoodGoodMediumMediumMedium12PassMediumMediumMediumMedium13MediumPoorMediumPassMedium14MediumMediumGoodGoodGood15PoorPassMediumMediumPassThrough the above evaluation results, the evaluation results of this paper are consistent with the expert evaluation results, so it is proved that the modeling method of evaluation index of special physical training for football players is more accurate and the practical application effect is better. Coaches can clearly find the differences in the first-level physical index and comprehensive physical fitness of different athletes, as well as their positions in the physical fitness of the whole group so as to provide an important theoretical basis for coaches to formulate training plans, monitor training, regulate training, and conduct individual training for different football players in a timely and accurate manner.On the basis of the above, the overall time of expert evaluation is compared with the evaluation method in this paper, and the specific comparison results are shown in Figure1.It can be seen from Figure3 that the evaluation time of specific physical training of football players by experts varies between 1.3 s and 2.5 s, while the evaluation time of specific physical training of football players by the proposed method is always lower than 0.5 s, indicating that the evaluation time of this method is shorter and the evaluation efficiency is higher.Figure 3
Comparison results of evaluation time.


## 4. Conclusion

Looking from the overall level at present, compared with the international level, the level of football in our country is more obvious, especially the men’s football still has a certain gap compared with the world-class teams. Therefore, scientific physical training and adjustment should be carried out to enable football players to have a higher level of physical fitness. Only in special physical training, this method obtains various feedback information of team training, which can better effectively control the whole training process. Therefore, it is necessary to effectively evaluate the effects of football players’ special physical training. This article studies the evaluation indicators of football players' special physical training. Our main contribution is analyzing the construction principle of the evaluation index system of football players’ special physical training, determining the evaluation primary index system, and constructing the evaluation index system of football players’ special physical training through comparison and screening. On this basis, the analytic hierarchy process is used to calculate the weight of the evaluation index, according to the weight calculation results of the evaluation index modeling using multilevel fuzzy comprehensive evaluation so as to get the evaluation results of the special physical training of football players. Evaluating the football athletes special physical training can improve the scientific level; special physical training for coaches provide scientific and systematic monitoring and accurately obtain the football player physical ability training state feedback information to provide a powerful theoretical guarantee, thus improving the special football player physical ability to provide important guidance and technology services.



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*Source: 1446971-2021-12-26.xml*