Investigating Acceleration and Deceleration Patterns in Elite Youth Football: The Interplay of Ball Possession and Tactical Behavior

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Dear authors,

Your study deals with an interesting topic! Recording match data to assess a player's performance over a longer period of time, but also during a match, could be helpful when deciding on a player change or for load management. 

Basically, I think your contribution is good! However, I have included some comments in the PDF. 

If you have any questions, please don't hesitate to ask.

Best regards

Comments for author File: Comments.pdf

Author Response

Reviewer 1

Dear authors,

Your study deals with an interesting topic! Recording match data to assess a player's performance over a longer period of time, but also during a match, could be helpful when deciding on a player change or for load management.

Basically, I think your contribution is good! However, I have included some comments in the PDF.

If you have any questions, please don't hesitate to ask.

Best regards

 

RESPONSES TO COMMENTS MADE IN THE PDF:

Comment 1 (page 1, line 22):

There was a typo. It has been corrected.

Comment 2 (page 1, line 26):

There was a typo. It has been corrected.

Comment 3 (page 1, line 29):

There was a typo. It has been corrected.

Comment 4 (page 1, line 30):

There was a typo. It has been corrected.

Comment 5 (page 1, line 30):

There was a typo. It has been corrected.

Comment 6 (page 2, line 61):

There was a typo. It has been corrected throughout the text.

Comment 7 (page 3, line 127):

The name of the team has been added.

Comment 8 (page 3, line 130):

The number of accelerations and decelerations analysed in total and by position has been added.

Comment 9 (page 4, line 166):

The ball position frequency is 50 HZ. This data has been added.

Comment 10 (page 4, line 186):

Groups have been specified.

Comment 11 (page 4, line 187):

There was a typo. It has been corrected.

Comment 12 (page 5, line 199, table 1):

Table 1 has been modified for better readability.

Comment 13 (page 6, line 224, figure 3):

Graphic quality has been improved. As for the empty columns, this is because there are some minutes in which the team did not have possession of the ball.

Comment 14 (page 7, line 226, figure 4):

There was an error in this graph and it has been fixed. It now shows the average deceleration. The resolution has also been improved. 

Comment 15 (page 8, line 233):

There was a typo. It has been corrected.

Comment 16 (page 8, line 234):

There was a typo. It has been corrected.

Comment 17 (page 8, figure 3):

Graphic quality has been improved

Comment 18 (page 9, figure 4):

Graphic quality has been improved

Comment 19 (page 10, table 2):

There was a typo. It has been corrected.

Comment 20 (page 10, table 2):

The requested changes have been made; the table is now easier to read.

Comment 21 (page 10, table 2):

The position name has been changed.

Comment 22 (page 10, table 2):

The position name has been changed.

Comment 23 (page 11, figure 5):

The position names have been changed and ordered.

Comment 24 (page 11, line 315):

Editing and proof-reading throughout the text.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Dear authors,

Shapiro-Wilk has the better power comparatively with other tests of normality, especially in medium and small samples. The power of this test is greater than that of the Kolmogorov-Smirnov test because it also detects deviations caused by asymmetry (skewness) and flattening (kurtosis).

The recommendation is to redo the statistical calculations, adapted to the sample and the new data obtained, for correct discussions.

Author Response

Reviewer 2

Dear authors,

Shapiro-Wilk has the better power comparatively with other tests of normality, especially in medium and small samples. The power of this test is greater than that of the Kolmogorov-Smirnov test because it also detects deviations caused by asymmetry (skewness) and flattening (kurtosis).

The recommendation is to redo the statistical calculations, adapted to the sample and the new data obtained, for correct discussions.

 

RESPONSE: We appreciate the reviewer's valuable comment and the opportunity to correct the error. Indeed, to determine the normality of a variable in small samples, the preferred method is the Shapiro-Wilk test. The authors have reviewed and detected that there was a transcription error regarding the statistical test used; in our study we have used this statistical test that the reviewer rightly commented. We have corrected this drafting error in the description of the statistical methods used. Despite compliance with the assumption of normality for all the continuous variables analyzed in our study, we opted for nonparametric tests due to the heterogeneity of variances and the size of the sample and subgroups.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

Dear authors,

congratulations on good work!

Please check comments.

Comments for author File: Comments.pdf

Comments on the Quality of English Language

Minor English corrections needed.

Author Response

Reviewer 3

Dear authors,

congratulations on good work!

Please check comments.

I have carefully reviewed manuscript of Conde-Pipo et al. titled: " Investigating Acceleration and Deceleration Patterns in Elite Youth Football: The Interplay of Ball Possession and Tactical Behavior ". First of all - -wise good first draft of a paper for long time, and I see that authors are really experienced in their work! Please check the comments for your manuscript:

 

Abstract

Well written

RESPONSE: The authors are grateful for the reviewer's comments on the Abstract section.

 

Introduction

Very good introduction with many relevant and new references congratulations!

RESPONSE: The authors are grateful for the reviewer's comments on the Introduction section.

 

Methods

do research on more matches? Or official matches. Friendly matches in general don t have the same performance indicators as official matches. Generally, I am really satisfied with methods section.

 

RESPONSE: The authors are grateful for the reviewer's comments on the Methods section. Kinexon provided the university with network devices, local position systems for players, and a ball with an integrated positioning system for a limited period of time. Due to this, we were unable to analyze more matches. However, the data we collected during this time is of high quality and will be valuable for future analysis.

 

Results

p should be italic

RESPONSE: All p have been changed to italic.

 

Discussion

Please add practical implications. What are your recommendations? Especially regarding training which you have mentioned in conclusion.

RESPONSE: A new paragraph has been added at the end of discussion section (lines 378-387).

 

Conclusions

Try to add some more conclusions and lines to final conclusion subtitle, especially considering your results

RESPONSE: Some new lines have been added to conclusion section (lines 410-415).

 

Lines 428 437 please correct this.

RESPONSE: Lines corrected

Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

Player-tracking technologies provide great opportunities for researchers and practitioners to evaluate athlete performance. It is commendable that the authors chose these methodologies for their study. Nevertheless, there are visible shortcomings that should be mentioned.

 

Line 41 I can't entirely agree with the authors who talk about accelerations and decelerations and claim that football is an aerobic and intermittent team sport. The very essence of the mentioned actions is highly anaerobic. In Line 48, they confirm that “Ac/Dec are physically and metabolically demanding actions even when they do not occur at high speed”. And in Line 53 claiming about…. <higher lactate levels>.

Line 63 How can the statement be understood: high-speed running threshold (18-30 km·h-1). For what age, and level players? How can there be such a wide threshold?

Materials and methods

 If I’m right 25 players of one team, data were collected for this study only from two matches. The question arises as to how the study was organized:

- Have players played against 2 different teams? I don't think that in two matches it is possible to talk about the tendencies of the game, especially tactical ones.  Different opponents lead to different behavior of players.

- How was playing time (min.) on the court allocated then?  How much time did the players spend on the field in two matches, if there were 25 of them, and only 10 could play without a goalkeeper?

- How the indicators are calculated? It is possible to obtain such data Number Ac/min 68.70(45.20) for WA (Table 2). This means an average of 1 acceleration per 1 second.

- I don't think the study can be considered reliable when the sample is 4-6 players per position and only two games are evaluated.

- Figure 5 does not explain the units in which the data are presented. Also, figure 2 does not explain whether it is a measure of one player, one position or the whole team.

Author Response

Reviewer 4

Player-tracking technologies provide great opportunities for researchers and practitioners to evaluate athlete performance. It is commendable that the authors chose these methodologies for their study. Nevertheless, there are visible shortcomings that should be mentioned.

Line 41 I can't entirely agree with the authors who talk about accelerations and decelerations and claim that football is an aerobic and intermittent team sport. The very essence of the mentioned actions is highly anaerobic. In Line 48, they confirm that “Ac/Dec are physically and metabolically demanding actions even when they do not occur at high speed”. And in Line 53 claiming about…. <higher lactate levels>.

REPONSE: The authors are grateful for the Reviewer's comments. We fully agree with the Reviewer's assessment. The paragraph has been modified to avoid confusion (lines 41-46).

 

Line 63 How can the statement be understood: high-speed running threshold (18-30 km·h-1). For what age, and level players? How can there be such a wide threshold?

RESPONSE: The threshold was incorrect. It has been rectified, and the category of players has been added (line 63).

 

Materials and methods

 If I’m right 25 players of one team, data were collected for this study only from two matches. The question arises as to how the study was organized:

- Have players played against 2 different teams? I don't think that in two matches it is possible to talk about the tendencies of the game, especially tactical ones.  Different opponents lead to different behavior of players.

RESPONSE: The opposing team was the same in both games. To analyse only two friendly matches is certainly a limitation of our study and as such is recognized therein (line 397).

 

- How was playing time (min.) on the court allocated then?  How much time did the players spend on the field in two matches, if there were 25 of them, and only 10 could play without a goalkeeper?

RESPONSE: These matches were unofficial, the club strategically rotated players between the two matches and the two halves of each match to prevent excessive fatigue accumulation. Consequently, the total number of players stands at 25. This limitation has been duly acknowledged in line 392.

 

- How the indicators are calculated? It is possible to obtain such data Number Ac/min 68.70(45.20) for WA (Table 2). This means an average of 1 acceleration per 1 second.

RESPONSE: This was possible thanks to the use of a system that works with a frequency of 20 Hz, continuously and accurately recording the movement of each player. Anyway, the acceleration data has been thoroughly reviewed again and confirmed to be accurate.

 

- I don't think the study can be considered reliable when the sample is 4-6 players per position and only two games are evaluated.

RESPONSE: While it's true that our study acknowledges the need for replication with a larger number of games, as outlined in its limitations, it's worth noting that many studies focus on analyzing playing positions within a single team, often with a smaller number of players per position. Despite this, the precision of the technology utilized affords considerable reliability, thereby establishing a solid groundwork for future research endeavors.

 

- Figure 5 does not explain the units in which the data are presented. Also, figure 2 does not explain whether it is a measure of one player, one position or the whole team.

RESPONSE: In figure 5, the units have been added. Figure 2 pertains to the whole team, and the footnote has been adjusted.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

-

Author Response

The authors are grateful for the efforts made by Reviewer 2 in reviewing the manuscript.

Reviewer 4 Report

Comments and Suggestions for Authors

The submitted manuscript has obvious and positive improvements, including tables and figures. However, a fundamental issue related to the study design was not adequately resolved. Like last time, I tend to repeat now that a properly formed research design is important in scientific research. It must provide the main variables that meet the criteria of connett validity.

Suppose the Elite Youth Football players sample is taken and the conclusions applied. In that case, two things are mandatory for team sports - a critical sample size and a sufficient number of cases from the study's environment.

If we take the whole sample, the total number of subjects would be optimal n= 25. However, when it is divided into 5, 6, and 4, etc. it becomes very complicated to provide scientific conclusions. An optimal number of matches would help solve this, but we don't have enough of them. Two friendly games during the championship, and all 25 players played during it. This means many players played only 1 game or less. In addition, nothing was said about the opponent, what level, age, and their experience. Therefore, the shortcomings of the study design do not allow us to state whether this is a central tendency of the studied population.

Therefore, other research quality issues cannot be considered, since the research design does not meet scientific article requirements.

Author Response

Reviewer 4 (round 2)

The submitted manuscript has obvious and positive improvements, including tables and figures. However, a fundamental issue related to the study design was not adequately resolved. Like last time, I tend to repeat now that a properly formed research design is important in scientific research. It must provide the main variables that meet the criteria of connett validity.

Suppose the Elite Youth Football players sample is taken and the conclusions applied. In that case, two things are mandatory for team sports - a critical sample size and a sufficient number of cases from the study's environment.

If we take the whole sample, the total number of subjects would be optimal n= 25. However, when it is divided into 5, 6, and 4, etc. it becomes very complicated to provide scientific conclusions. An optimal number of matches would help solve this, but we don't have enough of them. Two friendly games during the championship, and all 25 players played during it. This means many players played only 1 game or less. In addition, nothing was said about the opponent, what level, age, and their experience. Therefore, the shortcomings of the study design do not allow us to state whether this is a central tendency of the studied population.

Therefore, other research quality issues cannot be considered, since the research design does not meet scientific article requirements.

 

RESPONSE: The authors are grateful for the keen interest of Reviewer 4 in improving the manuscript in sections that are really important for the quality of the study.

Despite the youthfulness of the study population, the players studied are elite athletes, professionals who are part of the Sevilla FC youth team, one of the most prestigious in Europe. By analogy, in individual sports they would be comparable to members of a national team. Being immersed in this level of sport means a constant commitment to high performance, dedicating every day of the year to improving their skills and results. This means that they rarely have time to participate in research, as it is rare to interrupt their rigorous routines, and even less so to carry out interventions, which are usually conducted in training contexts rather than in real performance situations such as football matches, even if they are friendly.

Being part of this sporting elite means being part of a minority, which makes this population rare and difficult to study. However, their contributions to sport and health are invaluable.

As a result, most studies in sport focus on teams or athletes at lower levels, such as amateurs or recreational players. For this reason, coaches and physical trainers greatly value research such as ours, even if it is carried out with small samples, because of its usefulness in guiding their work, a limitation known to any professional in the field.

As evidence, a recent bibliographic review analysing accelerations and decelerations in football (Silva et al. 2023)* (reference 42 in the manuscript) found that, of a total of 40 recent studies, 36 had samples of less than 25 subjects and the rest had less than 35. This explanation has been included at the end of the discussion as part of the limitations of the study.

As for the opposing team, the authors thank Reviewer 4 for his comment, as this is indeed a relevant piece of information that should appear in the manuscript. The following sentence has been included in the material and method section: "The team they played against were of the same age, category and league".

We are therefore very grateful to you and ask you to reconsider the validity of our study, which was carried out with professionalism, although limited by its focus on sports performance.

 

*Silva H, Nakamura FY, Beato M, Marcelino R. Acceleration and deceleration demands during training sessions in football: a systematic review. Sci Med Footb. 2023 Aug;7(3):198-213. doi: 10.1080/24733938.2022.2090600.

Author Response File: Author Response.pdf