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  <front>
    <journal-meta />
    <article-meta>
      <title-group>
        <article-title>The Application of Machine Learning on the Injury Prediction of Soccer Players</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Davronbek Malikov</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Jaeho.Kim</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>Gyeongsang National University</institution>
          ,
          <addr-line>Jinju-si , 53828</addr-line>
          ,
          <country country="KR">South Korea</country>
        </aff>
      </contrib-group>
      <abstract>
        <p>Soccer player lives with a high risk of injury since soccer is one of the sports activities with relatively high injury incidence compared with many other sports. Injuries can be a huge influence not only player's career and financial situation but also it is the reason for soccer changing the coach's game tactics as well as for directors of clubs have to find a new player. In order to reduce the risk of getting injured by predicting the probability of soccer players' injuries for the new season, we conduct research in this paper. In this paper, we propose parameters that are connected each other and we collected using a non- technical way while most of the recent research provides technical ways such as GPS tracking technology or wearing devices. Moreover, we provide the accuracy of injury prediction and estimation of recovery time by using supervised classification machine learning models.</p>
      </abstract>
      <kwd-group>
        <kwd>1 non-technical data collecting</kwd>
        <kwd>data analysis</kwd>
        <kwd>soccer injury prediction</kwd>
        <kwd>machine learning for a soccer injury</kwd>
      </kwd-group>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>1. Introduction</title>
      <p>Soccer players face numerous challenges throughout their
careers, but one of the most significant is the risk of injury.
Injuries can result in players having to take extended breaks
from the game, incurring substantial rehabilitation costs, and
in some cases, even ending their careers prematurely.
Therefore, developing effective injury prevention and
management strategies is crucial to ensure the long-term
health and success of soccer players..In this paper, we propose
an application of machine learning the predicting the
likelihood that injury cases among professional soccer players
while playing. Machine learning Naive Bayes model will be
used in order to identify the player’s risk of injury for the next
soccer season and we check it by using training and testing
data collected from professional sports websites. A purposing
model will be created based on the connection of variables
that play an important role in this research. In addition to the
benefits for soccer players and coaches, our analysis and
classification report can also have a positive impact on the
overall performance and success of the team. By being able to
predict the likelihood of injury, coaches can make informed
decisions about player selection and substitution, adjust
training regimes and playing tactics, and ultimately reduce the
number of injuries sustained by their players.</p>
    </sec>
    <sec id="sec-2">
      <title>2. Related Work</title>
      <p>
        The training data and Machine Learning models are
becoming a fundamental part of professional sports,
especially in predicting the risk of sports injury. Numerous
academic papers have been published on the topic of machine
1st International Workshop on Intelligent Software Engineering, 2022
davronbekmalikov96@gmail.com (Davronbek Malikov);
jaeho.kim@gnu.ac.kr (Jaeho Kim)
learning applications in the prediction of injuries in sports,
including soccer.[13,14.]For example, the relationship
between injury risk and the so-called monotony was defined
in basketball and moreover, the ratio and the standard
deviation of the session load recorded in the past week [
        <xref ref-type="bibr" rid="ref1">1</xref>
        ]. In
the case of skating the product of the perceived exertion and
the duration of the training session is proposed where the
training session is measured by the session load. The skater
can be caused by ‘overtraining syndrome’ and is considered a
risk of injury when the session load is out of balance and the
skater’s ability to fully recover,before the next session [
        <xref ref-type="bibr" rid="ref2">2</xref>
        ].
Furthermore, the application of machine learning models has
been playing a great role in order to conduct of research on
predicting the risk of injury in Soccer and American Football
where the linear regression model is used [
        <xref ref-type="bibr" rid="ref3 ref4">3,4</xref>
        ]. Machine
learning is important for automatically learning and helps to
improve small efforts of programming. Especially, in the case
of performing tasks that are very complex and difficult for
humans in between fixed time then the machine learning
model is very useful [
        <xref ref-type="bibr" rid="ref5 ref6">5,6</xref>
        ]. Another example of applying linear
regression model is applied to predicting England Premier
League soccer players who play in the forward position [
        <xref ref-type="bibr" rid="ref7">7</xref>
        ].
According to the k-fold cross- validation, the testing and
training scores can be checked for the risk of injury of a group
of players for the next games and the more important focus of
that research is the dependent variable which is the distance
of players for each game [
        <xref ref-type="bibr" rid="ref7">7</xref>
        ]. Machine learning linear
regression is not the only model for predicting injury and also
decision trees also have been used to figure out
non-concontact soccer injuries [
        <xref ref-type="bibr" rid="ref8">8</xref>
        ] By using the ‘ADASYN’
oversampling technique [
        <xref ref-type="bibr" rid="ref9">9</xref>
        ] data imbalance problem is solved
and 954 data recordings are collected by using GPS
technology. ACWR, the ratio of mean and standard
deviation(MSWR), and the exponential moving
average(EWMA) of each training load variable included in
this study in order to examine the classification model
      </p>
    </sec>
    <sec id="sec-3">
      <title>3. Data Introduction and model</title>
      <p>environment</p>
      <p>In this section, we provide an overview of the data used in
our analysis, as well as a description of its features and the
methods by which it was collected.</p>
      <sec id="sec-3-1">
        <title>3.1. Data Loading</title>
        <p>
          Data is indeed the heart of every machine learning project
and model. In order to develop accurate and effective
predictive models, it is essential to have access to high-quality,
relevant data that reflects the real-world phenomenon being
studied. This data should be comprehensive, encompassing a
range of variables and factors that are likely to impact the
outcome being predicted..In this work, we study 22
professional football players history of career who have been
playing in the top 5 five football. leagues in Europe, including,
La Liga in Spain, the Premier League in England, Ligue 1 in
France, the Bundesliga in Germany, and Serie A in Italy. The
players in our data set were carefully selected to provide a
representative sample of professional footballers playing in
the Forward and Midfield positions, which are known to be
particularly high-risk positions for injury. Players position
also reason for getting injury as we seen from the soccer
history[
          <xref ref-type="bibr" rid="ref15">15</xref>
          ]. Our dataset includes seven center-forwards, six
left-wingers, four right-wingers, three central midfielders, and
two attacking midfielders, reflecting a range of playing styles
and positions. By focusing on these key positions, we were
able to gain insights into the specific risk factors and injury
patterns associated with each, providing a more nuanced
understanding of injury likelihood among elite football
players. Our analysis of these players' injury histories and risk
factors will help inform injury prevention and management
strategies for players in similar positions, ultimately
promoting safer and more sustainable football practices. In
this study, we collected data on professional football players
from the transfermarkt.com website, which is a leading online
platform for sports data and analysis. It provides a wealth of
information on player statistics, career history, and injury
records, making it an ideal source for our research.
3.2.
        </p>
      </sec>
      <sec id="sec-3-2">
        <title>Model Environement</title>
        <p>Python has emerged as the preferred programming
language for data science, data analysis, and machine learning
projects due to its versatility, simplicity, and robust ecosystem
of libraries and tools. Python provides a powerful set of
libraries and frameworks for handling large datasets,
statistical analysis, and visualization, including NumPy,
Pandas, and Matplotlib. In case of machine learning there are
many Integrated Development Environments (ID provides a
range of powerful machine learning frameworks, such as
Scikit-learn, TensorFlow, and PyTorch, which enable
developers to build sophisticated machine learning models
with ease. These frameworks provide a wide range of
algorithms and techniques for supervised and unsupervised
learning, as well as tools for model evaluation and
optimization to run Python code, and data analysis, including;
data cleaning, and data integration, and more importantly
allows access to the Python machine learning libraries which
will help use machine learning models.</p>
        <p>For our data analysis and visualization tasks, we used the
Jupyter Notebook as our integrated development environment
(IDE) and Python version 3.9.12 as our programming
language. Jupyter Notebook provides an interactive
environment that allows us to write and execute code,
visualize data, and communicate our findings in an organized
and accessible format.
4.</p>
      </sec>
    </sec>
    <sec id="sec-4">
      <title>Model Evaluation</title>
      <p>In this section, we will introduce the machine learning
model that we used to predict injury likelihood among
professional soccer players, as well as the Python library that
we utilized to implement the model.</p>
      <p>Initially, we introduce the model employed in our
experiment and subsequently present the outcomes of our
experiment with a classification report. We utilized two
techniques to obtain the results; first, we provide the results
for a group of professional soccer players, and secondly, we
provide the outcomes of individual players based on our
model. This approach helped us to evaluate the accuracy and
efficiency of our model in identifying the risk of injuries for
both groups of players. Additionally, this helped us to analyze
the performance of our model in predicting the likelihood of
injuries for specific players.
4.1.</p>
      <sec id="sec-4-1">
        <title>Model Introduction</title>
        <p>In our research project, we opted to use a classification
machine learning model due to the fact that our dataset
possessed the necessary characteristics to enable classification.
Classification is one of the fundamental problems in machine
learning, and it involves assigning a class or category to a
given data point. In this context, we used various classification
machine learning models to classify data points based on their
features. These models are Decision Tree, Random Forest,
KNearest Neighbors (KNN), and Naive Bayes. Each
classification model has its strengths and weaknesses, and the
choice of which to use depends on the nature of the data and
the problem at hand.</p>
        <p>
          By leveraging a suitable classification algorithm, we aimed
to predict the likelihood of injury among professional soccer
players. In our work we use the Naive Bayes model which is
a supervised classification machine learning model. The
Naive Bayes model, which is a type of probabilistic algorithm,
is based on low conditional probability and is highly
interpretable. This algorithm is suitable for both binary and
multi-class classification problems, making it a versatile
choice for predicting injury likelihood among professional
soccer players. Additionally, Naive Bayes is known for its
relatively fast training and prediction times, making it a
popular choice in many machine learning applications. In our
work we have a binary class classification problem such that
0 for not injury and 1 is injury and find predictive value for
soccer player risk of injury. In this research , we use
sci-kitlearn library [
          <xref ref-type="bibr" rid="ref11">11</xref>
          ] that is available in python alongside Naive
Bayes. We create 2 parts of data that will use for fitting and
predicting values. Our research methodology involved the use
of both dependent and independent variables, which were
incorporated into our training and testing datasets. By
including both types of variables in our analysis, we aimed to
develop a robust machine learning model that could
accurately predict injury likelihood among professional
soccer players. In our case independent variables such as the
total number of games in the season, the number of minutes
in a season, the total number of games in FIFA days, the
number of games in CHL/EL, and the total number of an
important game. We considered the total number of games
including such games in the top five football leagues CHL/EL
and Europe Conference League group stages, World Cup, and
Olympic Games as well as playoff rounds. Furthermore,
dependent variable by default of machine learning models and
in our case, we are involving the relationship between
independent variables with a single dependent variable which
is injury
        </p>
      </sec>
      <sec id="sec-4-2">
        <title>4.2. Evaluation of model and classification report</title>
        <p>To develop our machine learning model, we began by
splitting our dataset into two separate sets: a training dataset
and a testing dataset. This approach enabled us to train our
model on a portion of the data and then test its performance
on an independent subset. Fig 1 illustrates the variables of our
data set alongside their characters of them. We can see from
the Figure that it includes 6 columns including dependent and
independent variables, and also an index of data from 0 to 301.</p>
        <p>In addition to providing insight into the variables included
in our dataset, Figure 1 also highlights some important
characteristics of the data itself. Specifically, it indicates that
our dataset is complete, with no null or missing values, and
that all variables have been recorded as integers. Additionally,
the memory usage of our dataset is relatively low, at just 14.4
KB. These findings suggest that our dataset is well-organized
and suitable for use in developing our machine learning model.</p>
        <p>Moreover in the figure 2 we can see the injury indicator that
is machine learning model refers to a variable or feature that
is used to predict the likelihood or risk of injury. According to
the our dataset and the number of injury history we can see
the deep inside of information of players</p>
        <p>Furthermore, to split data into training and testing we
import the train_test_split function from
sklearn.cross_validation library and then 80% of the total data
for the training set and 20% of data for testing . Then 241
samples were used for training and other remaining 61
samples for testing</p>
        <p>Gaussian Naive Bayes is a popular classification algorithm
that works well with continuous data and assumes that the
features are normally distributed. It is based on Bayes'
theorem and assumes independence between features. The
algorithm works by calculating the probabilities of each class
for a given set of features, and then choosing the class with
the highest probability as the predicted class. In our case, we
used Gaussian Naive Bayes to train our model due to its
effectiveness in training data and its ability to handle
continuous data.</p>
        <p>Moreover, an important part of the model is Evaluating
Process. In this process, we test our data and we take a result
with the accuracy of our model.</p>
        <p>In Fig.3, the classification report of the model is given. The
precision and recall score of the model is 87 and 89 percent
for the injury sample (1) respectively where the precision
score is injury identification and recall are the proportion of
actual injury cases that are correctly classified, f1-score is the
mean of the precision and recall. We can see by f1-score the
performance of these two classifiers in our case is 88 percent
while the support is the number of samples for testing data
with 61 total numbers 17 for not-injury and 44 for injury cases
since we used 20 percent of data for testing our model.</p>
        <p>Moreover, the accuracy of our model is 82 percent. The
macro average of the model is the most straightforward
among other types of averaging methods and for precision is
78 percent and with the same 77 percent for recall and f1-score
one of the differences between a macro and a weighted
average is considering the proportion of each support of
classes is considered in the weighted average and our case
weighted average is same 82 percent for precision and recall
and f1-score.</p>
        <p>In our experiment we have determined injury values with
classification report for all 22 professional soccer players that
are in our dataset. However individual players can be selected.</p>
        <p>According to our proposed model, we divided players into
two groups, high-risk injury players and low-risk of injury
players. The player who is a maximum number of injury
levels that is based on the player’s history of injuries can be
selected individually. G. Bale’s injury level is higher than
other players with 8 and while P. Foden with R.Mahrez is
minimum level 1 as given in Fig.3.</p>
        <p>We can see from Figure 4 that the frequency of injury is
given in the y-axis while the name of the player whose level
of injury lies between G.Bale and P.Foden who are max and
min of level injury in our data respectively is given in the
xaxis.Then G. Bale’s likelihood of injury next season with 87
percent and P. Foden has a less injury chance</p>
      </sec>
    </sec>
    <sec id="sec-5">
      <title>5. Conclusion</title>
      <p>The field of machine learning has made remarkable
advancements, particularly in the area of sports medicine and
sports science. With the help of machine learning algorithms,
researchers and practitioners are now able to analyze large
datasets and gain insights into athlete performance and injury
risk. These insights can be used to develop personalized
training programs, prevent injuries, and improve overall
athletic performance in the different sports.</p>
      <p>Predicting the likelihood of the risk of a soccer injury is the
focus of our research, and in order to achieve this goal, we
have proposed a classification machine-learning model
learning model to predict the likelihood of the risk of a soccer
injury. In order to collect the necessary data for our research,
we utilized a well-known and reputable soccer website called
transfermarkt.com. This website is widely recognized as a
reliable source for obtaining valuable information on soccer
players, such as their career history, transfer fees, market
value, and more. By using this website, we were able to access
and gather data on the 22 professional soccer players who
have played in the top five leagues in Europe, including La
Liga in Spain, the Premier League in England, Ligue 1 in
France, the Bundesliga in Germany, and Serie A in Italy. This
data set enabled us to conduct a thorough analysis of each
player's injury history and assess their level of risk for future
injuries. The classification report is a useful tool to evaluate
the performance of a classification model. It helps to
understand the accuracy of the model by providing metrics
such as precision, recall, and F1 score for each class. In our
study, we used a classification report to evaluate the
performance of our machine learning model for predicting the
likelihood of injury in soccer players. In addition, we
evaluated the accuracy of our model to determine how well it
fits our research objectives. To provide a more comprehensive
evaluation, we reported two types of averages, namely macro
and weighted. The macro-average calculates the unweighted
mean of the precision, recall, and F1-score across all classes,
while the weighted average takes the average weighted by the
number of samples in each class. By reporting both averages,
we can gain insights into how well our model performs overall
and how well it performs for individual classes.</p>
      <p>To improve the accuracy and applicability of our model, we
plan to further develop our approach in future work. Our focus
will be on extending our study to include a larger sample size
of soccer players. Additionally, we will explore the possibility
of predicting and preventing specific types of injuries in our
experiment.</p>
      <p>In the professional soccer world, it is a well-known fact that
aspiring soccer stars often have to face prolonged periods of
time out of games due to soccer injuries. Hence, to achieve
success and become a soccer star, it is crucial to avoid such
injuries. For instance, the examples of Ronaldo and Messi,
who have managed to steer clear of serious soccer injuries that
require lengthy recovery periods, highlight the importance of
injury prevention in achieving success in this sport.</p>
      <p>The primary objective of our research was to assist aspiring
soccer players in achieving success and reaching the pinnacle
of their sport, just like Cristiano Ronaldo and Lionel Messi.
By doing so, we aimed to contribute towards the advancement
of soccer as a whole and provide soccer fans with an even
more exciting and competitive game.</p>
      <p>In addition, the proposed machine learning model can help
coaches in developing preventive measures to avoid player
injuries. By identifying players with a high risk of injury,
coaches can create personalized training programs and make
adjustments to their playing tactics to minimize the chances
of injury. This could not only benefit the team's performance,
but also save the team money by avoiding medical expenses
and lost playing time.</p>
      <p>Furthermore, the model can be used to compare the injury
risk of players across different teams and help in the scouting
process for potential new players. In addition to being
beneficial for coaches and players, our model can also provide
value to team scouts. By analyzing specific players before
making decisions about their recruitment, scouts can more
easily assess the player's likelihood of consistent performance
in the upcoming season. This not only saves time and money
for teams, but it also allows them to make more informed
decisions about player recruitment. Overall, our model has the
potential to significantly impact the decision-making process
of teams and improve their overall performance.
improve our understanding of injury risk and predic</p>
    </sec>
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