Effect of a 12-Week Football Programme on Body Composition, Physical Condition, and Analysis of Physical Demands in Young Male Children

Round 1

Reviewer 1 Report

The topic of the paper is interesting and I congratulate the authors for their work.

The article presents a clear and precise introduction to the aim of the research. The references are current and appropriate to the subject matter.

The methodology used in the research is correct, as both the groups and the times and tests used are appropriate for the study population. They have used state-of-the-art technology for the analysis of the variables used and this makes the article very innovative. With regard to the sample, it would be interesting to specify whether both groups were engaged in any kind of activity before the football training programme. 

The statistical analysis used is correct for the proposed methodology.

In the results section, I propose that table 1 be separated into two different tables. One referring to the results of body composition, which would be in the first section of the results, and another different table for the second section, with the results of physical condition. 

This would make it easier for the reader to follow the results, since the numerical presentation of the results in the text makes it difficult to follow them in the table if they are not followed by the results.

The discussion is in line with current results and references.

I recommend that the authors provide a more in-depth explanation of the training programme carried out, in order to be able to make practical recommendations. It would be very interesting to explain the objectives of the training sessions in order to be able to reproduce the study conditions in other populations and corroborate the results. 

Author Response

The topic of the paper is interesting and I congratulate the authors for their work.

We really appreciate the comments of the reviewer

The article presents a clear and precise introduction to the aim of the research. The references are current and appropriate to the subject matter.

Thank you.

The methodology used in the research is correct, as both the groups and the times and tests used are appropriate for the study population. They have used state-of-the-art technology for the analysis of the variables used and this makes the article very innovative. With regard to the sample, it would be interesting to specify whether both groups were engaged in any kind of activity before the football training programme.

Thank you very much for your comments. Added to the manuscript.

The statistical analysis used is correct for the proposed methodology.

Thank you.

In the results section, I propose that table 1 be separated into two different tables. One referring to the results of body composition, which would be in the first section of the results, and another different table for the second section, with the results of physical condition.

This would make it easier for the reader to follow the results, since the numerical presentation of the results in the text makes it difficult to follow them in the table if they are not followed by the results.

Thank you for your comments. The tables have been split as you suggested.

The discussion is in line with current results and references.

Thank you so much.

I recommend that the authors provide a more in-depth explanation of the training programme carried out, in order to be able to make practical recommendations. It would be very interesting to explain the objectives of the training sessions in order to be able to reproduce the study conditions in other populations and corroborate the results

Thank you very much for your suggestion. The training objectives have been added to the manuscript.

Reviewer 2 Report

Dear Authors

 

You have written an interesting paper focusing on the analysis of the effects of a 12-week football programme on the body composition (fat mass, muscle mass, and bone mass), as well as the physical demands and loads required in training and matches in a young population (U10–U12).

Introduction: I don't see any studies supporting that there is any BMC adaptation in 12 weeks which would back up your main rationale. Please amend.

Methods:

How did you determine your sample size (G*Power or any other method)? Report

How were they divided into 2 groups? report

Body composition measurements - report at what time was the measurement done and what were the instructions 1 day prior to the testing.

CMJ, VO2 max and handgrip tests need to be better explained - how many repetitions, which results were taken into further analysis, which arm was tested, etc. Which variables were analysed? Please be specific.

What was the exact order of the test and what was the break between them? Report

The limitations of the study paragraph is missing at the end of the discussion. Add

 

Overall the paper is well written, However, the methods section needs to be addressed for greater clarity and reproducibility. Therefore, I recommend a major revision.

Kind regards

 

 

 

 

 

 

Author Response

You have written an interesting paper focusing on the analysis of the effects of a 12-week football programme on the body composition (fat mass, muscle mass, and bone mass), as well as the physical demands and loads required in training and matches in a young population (U10–U12).

Introduction: I don't see any studies supporting that there is any BMC adaptation in 12 weeks which would back up your main rationale. Please amend.

Thank you very much for your comment. The aim of the study is to look at 12 weeks to see if there is any effect on bone mass, as all the studies we have found are for different time periods. In addition, we have evidence that a 12-week training or football programme has produced improvements in BMC, body composition and fitness in different populations. This evidence has been added to the introduction.

Methods:

How did you determine your sample size (G*Power or any other method)? Report

Thank you very much for your comment. Using the WebPower system. Here is the image of the programme with the result.

How were they divided into 2 groups? Report

Thank you for your input. The division of the groups was not random. Since the football group were children predisposed to play football, while the control group were not predisposed to play football.

Body composition measurements - report at what time was the measurement done and what were the instructions 1 day prior to the testing.

Body composition assessments were performed in the evening, between 17:00 and 20:00 at each measurement. Prior instructions were not to ingest calcium supplementation 24 hours before the test. Evacuate major and minor waters before the test. Perform the test in short-sleeved, thin clothing or underwear. Same clothing for both measurements. No metal items such as watches, bracelets, rings, etc. should be worn.

CMJ, VO2 max and handgrip tests need to be better explained - how many repetitions, which results were taken into further analysis, which arm was tested, etc. Which variables were analysed? Please be specific.

Thank you for your suggestion. It has been added in the mansucrit.

What was the exact order of the test and what was the break between them? Report

First, they performed the body composition assessment on the DXA. The next day they performed the CMJ jump, handgrip and course navette tests. Firstly, the CMJ jump, 3 jumps with 1 minute rest between each jump. Then after 5 minutes they performed the handgrip test, 3 repetitions with the dominant hand with 1 minute rest between each repetition. Finally, after 5 minutes of rest, they performed the Course navette test.

The limitations of the study paragraph is missing at the end of the discussion. Add

 Thank you very much for your comment. The limitations paragraph has been added to the discussion.

Overall the paper is well written, However, the methods section needs to be addressed for greater clarity and reproducibility. Therefore, I recommend a major revision.

Reviewer 3 Report

The paper by Hernandez-Martin et al. investigated the body composition chabges after a 12-week football programme and the associated physical demands in a relatively large (n=20) sample of young football players. A similar number of age-matched “sedentary” children was the control for body composition.

There are several concerns with this paper, which are itemized below.

1. The experimental design does not match the aim of the study. In fact, the authors state in the introduction that "the aim of this study was to describe and analyse the effects of a 12-week football programme on body composition (fat mass, muscle mass, and bone mass), as well as the physical demands and loads required in training and matches in a young population." However, they enrolled in the study children already playing football, so that the previous effect of football practice could not be evaluated. Further, a control group was included, whose role is not explained/justified. By the way, the control group was comprised of "sedentary" children; therefore, marked differences in body composition between the football and control group could be anticipated, and were actually found. A control group comprised of "physically active" childred would have better highlighted the specific effect of football training (see e.g., DOI: 10.1249/01.mss.0000205117.11882.65).

2. The Introduction is largerly out of focus, especially the first part.

3. The M&M section is lacking of crucial information e.g., was a a-priori sample size calculation made; where the children male, female, or a mix of males and females; how long was previous football exposure; how many football players were included in the three playing position categories; was numerosity in all playing position categories sufficient to justify the use of ANOVA as the statistical tool; how many children were included in the U10 and U12 categories; was maturation considered (Tanner stage ecc.).

4. The first paragraph of the Discussion is merely a repetition of results. The second paragraph mainly deals with the expected, obvious differences between football players and controls and no attempt is made to highlight the relevance of finding to the aim of the work. In the third paragraph, only results in the football group are considered; the role of age per se in affecting bone mineral is recognized but not actually discussed in detail, nor an explanation is given for the lack of any age adjustement of results. In the fourth papragraph, the discussion of results is very poor.

5. A further concern is the lack of any correlation analysis between body compostion variables (and their changes after intervention) and functional variables.

Overall, the paper presents serious flaws that prevent, in my opinion, acceptance for publication in its present form.

   

 

 

Author Response

Article titled: „Effect of a 12-Week football programme on body composition and analysis of physical demands in young children”. The aim of the study was to analyse the effects of a 12-week football programme on body composition (fat mass, muscle mass, and bone mass), as well as the physical demands and loads required in training and matches in 40 young children (U10–U12). Two groups were included: foodball players and control.

Introduction.

Please check the numbers of references – are all of them correctly? For example, reference no 8 as the PA recommendation – at page 10, it is no 9, not 8. Check them all, in the full manuscript.

Thank you for your suggestion. References have been checked throughout the manuscript.

Please address updated PA recommendations – the cited ones are from 2010, but the newest were published by WHO in 2020.

The reference has been updated.

Correct the format of using parameters such as “VO2max” – it should be VO₂ max

Formatting has been corrected throughout the manuscript.

Materials and Methods.
Is BMI described in the text: “The FG was formed by 20 children from a football team in Toledo (Spain) (9.3 ± 1.2 years and 18.0 ± 2.1 kg/m2)”. It must be clear.

Thank you for your suggestion. BMI has been added in the manuscript.

Is BMI accurate indicator for children? Please explain and describe it.

Thank you very much for your appreciation.

BMI has its limitations, in research in children. It has limitations in differentiating body fat from lean (fat-free) mass and its low-to-moderate sensitivity is problematic for clinical applications. In overweight children, the increase in BMI may be due to an increase in fat mass or fat-free mass. BMI could be divided into fat-free mass index and fat mass index. For children, BMI is calculated in the same way as for adults, but BMI results are interpreted differently, they must be relative to the age and sex of the child. Like other factors, such as height difference and level of secondary sexual maturation, the relationship between BMI and body fat among children and the amount of body fat changes with age and varies by sex.

Chung, S. (2015). Body mass index and body composition scaling to height in children and adolescent. Annals of pediatric endocrinology & metabolism, 20(3), 125-129.

Therefore, in this research it is only used descriptively for the sample, not as an analysis or assessment of body composition.

 

It is not clear: please explain “three-month football intervention programme” and “12-Week football programme” – is it the same programm, or is 12-week programm a part of three-month programm? Or did 12-week program start after the three-month program had been completed? If it is the same, please use the same expression.

Thank you very much for your appreciation. It is the same, it has been corrected and the same expression has been used.

Did FG play football earlier, before the 12-week program started? How long did they play football?

Thank you very much for your comment. Yes, the football group had subjects with 1 year of experience. This consideration has been included in the limitations section.

How was physical activity assessed? Did they practice another sport?

Thank you very much for your comment. They did not play any other sport, only football and physical education classes at school.  This consideration on the assessment of physical activity has been included in the limitations section.

Again, correct the format of units:  kg/m2 -> kg/m², and the next ones: “BMD in g / cm2”, “Z5: 13.1–17 km·h-1”, “2.7 m·s-2” – it must be the same format for all units – with or without space, etc.,  but consequently.

The format of the units in the manscript has been corrected and unified.

Please use the same expression DF, MF, FW or DFs, MFs, FWs

The same expression has been unified throughout the document (DFs, MFs, FWs).

Results.

Results are hard to read, too many data in the text. What are “TE”, “ET”?

Thank you very much for your comment. "TE" AND "ET" is the effect size, it has been replaced in the document by "ES".

The data in the results have been simplified to make them easier to read

Table 1and Table 2 must be formatted in a different way – it is very hard to read them.

Thank you very much for your suggestion. The format has been modified for better compression.

Author Response File: Author Response.pdf

Reviewer 4 Report

 

Article titled: „Effect of a 12-Week football programme on body composition and analysis of physical demands in young children”. The aim of the study was to analyse the effects of a 12-week football programme on body composition (fat mass, muscle mass, and bone mass), as well as the physical demands and loads required in training and matches in 40 young children (U10–U12). Two groups were included: foodball players and control.

 

Introduction.

Please check the numbers of references – are all of them correctly? For example, reference no 8 as the PA recommendation – at page 10, it is no 9, not 8. Check them all, in the full manuscript.

Please address updated PA recommendations – the cited ones are from 2010, but the newest were published by WHO in 2020.

Correct the format of using parameters such as “VO2max” – it should be VO₂ max

Materials and Methods.
Is BMI described in the text: “The FG was formed by 20 children from a football team in Toledo (Spain) (9.3 ± 1.2 years and 18.0 ± 2.1 kg/m2)”. It must be clear.

Is BMI accurate indicator for children? Please explain and describe it.

It is not clear: please explain “three-month football intervention programme” and “12-Week football programme” – is it the same programm, or is 12-week programm a part of three-month programm? Or did 12-week program start after the three-month program had been completed? If it is the same, please use the same expression.

Did FG play football earlier, before the 12-week program started? How long did they play football?

How was physical activity assessed? Did they practice another sport?

Again, correct the format of units:  kg/m2 -> kg/m², and the next ones: “BMD in g / cm2”, “Z5: 13.1–17 km·h-1”, “2.7 m·s-2” – it must be the same format for all units – with or without space, etc.,  but consequently.

Please use the same expression DF, MF, FW or DFs, MFs, FWs

Results.

Results are hard to read, too many data in the text. What are “TE”, “ET”?

Table 1and Table 2 must be formatted in a different way – it is very hard to read them.

Author Response

1. The experimental design does not match the aim of the study. In fact, the authors state in the introduction that "the aim of this study was to describe and analyse the effects of a 12-week football programme on body composition (fat mass, muscle mass, and bone mass), as well as the physical demands and loads required in training and matches in a young population." However, they enrolled in the study children already playing football, so that the previous effect of football practice could not be evaluated. Further, a control group was included, whose role is not explained/justified. By the way, the control group was comprised of "sedentary" children; therefore, marked differences in body composition between the football and control group could be anticipated, and were actually found. A control group comprised of "physically active" childred would have better highlighted the specific effect of football training (see e.g., DOI: 10.1249/01.mss.0000205117.11882.65).

Thank you very much for your comment. The aim of the research has been modified by comparing children who play football with children who lead a sedentary life. The differences obtained in the first measurement already show the importance of physical activity on body composition. In addition, the previous experience of children playing football has been added to the limitations section.

2. The Introduction is largerly out of focus, especially the first part.

Thank you very much for your comment. The introduction has been amended.

3. The M&M section is lacking of crucial information e.g., was a a-priori sample size calculation made; where the children male, female, or a mix of males and females; how long was previous football exposure; how many football players were included in the three playing position categories; was numerosity in all playing position categories sufficient to justify the use of ANOVA as the statistical tool; how many children were included in the U10 and U12 categories; was maturation considered (Tanner stage ecc.).

Thank you very much for your suggestions. But we had limitations with the GPS devices, as we had 20 devices. We would have liked to have 20 more devices, but it was not the case. 10 children were U10 and 10 children were U12. More information has been added in the methodology section.

Here is the sample size calculation.

4. The first paragraph of the Discussion is merely a repetition of results. The second paragraph mainly deals with the expected, obvious differences between football players and controls and no attempt is made to highlight the relevance of finding to the aim of the work. In the third paragraph, only results in the football group are considered; the role of age per se in affecting bone mineral is recognized but not actually discussed in detail, nor an explanation is given for the lack of any age adjustement of results. In the fourth papragraph, the discussion of results is very poor.

Thank you very much for your suggestions. The discussion has been modified.

5. A further concern is the lack of any correlation analysis between body compostion variables (and their changes after intervention) and functional variables.

Thank you very much for your suggestion. This research does not aim at a correlation, furthermore other reviewers have considered the results section to be too long, so it was decided to eliminate these results as no significant relationship was found in the interaction with time. The objective is to analyse the physical demands in training and matche.

Overall, the paper presents serious flaws that prevent, in my opinion, acceptance for publication in its present form.

 

Round 2

Reviewer 2 Report

Dear Authors

 

Thank you for addressing my comments and suggestions. The paper's quality improved.

 

However, there is still some minor info that needs to be added:

Introduction: add gender - male

How did you determine the dominant hand in participants? Report

Report the reliability and validity of your DXA device from previous studies.

Was there any demonstration before CMJ and the ability for participants to perform practice jumps? report

Report the sample size calculations as they are in this paper (the picture attached can not be opened): 10.3390/biology10111199

Add the time of the measurements in the text.

What was the warp up before each session? Report

Limitations section - was done only on males - therefore the results can not be generalised to all children.

I would also try to add gender specificity in the title so it is not misleading. Please amend.

 

Kind regards

Author Response

Thank you for addressing my comments and suggestions. The paper's quality improved.

However, there is still some minor info that needs to be added:

Introduction: add gender – male

Thank you very much for your suggestion. It has been added in the introduction in the paragraph on the objective of the study.

How did you determine the dominant hand in participants? Report

Thank you very much for your comment. Dominant hand was determined by asking participants which hand they use most frequently to perform the greatest variety of tasks, such as writing, eating, painting, waving, pointing, etc., as indicated in the following study.

 Ní Choisdealbha, Á., Brady, N., & Maguinness, C. (2011). Differing roles for the dominant and non-dominant hands in the hand laterality task. Experimental Brain Research, 211, 73-85.

Report the reliability and validity of your DXA device from previous studies.

Thank you very much for your comment, the Dxa device used in the research has previously been validated and tested for reliability alongside other methods of measuring body composition as we see in the following article:

von Hurst, P. R., Walsh, D. C., Conlon, C. A., Ingram, M., Kruger, R., & Stonehouse, W. (2016). Validity and reliability of bioelectrical impedance analysis for estimating body fat percentage versus air displacement plethysmography and dual-energy x-ray absorptiometry. Nutrition & Dietetics, 73(2), 197-204.

Also, several studies have previously used this device:

Tornero-Aguilera, J. F., Villegas-Mora, B. E., & Clemente-Suárez, V. J. (2022). Differences in body composition analysis using DEXA, Skinfold and BIA methods in young football players. Children, 9(11), 1643.

Munguia-Izquierdo, D., Suárez-Arrones, L., Di Salvo, V., Paredes-Hernández, V., Alcázar, J., Ara, I., ... & Méndez-Villanueva, A. (2018). Validation of field methods to assess body fat percentage in elite youth football players. International journal of sports medicine, 39(05), 349-354.

Núñez, F. J., Munguía-Izquierdo, D., & Suárez-Arrones, L. (2020). Validity of field methods to estimate fat-free mass changes throughout the season in elite youth soccer players. Frontiers in physiology, 11, 16.

Was there any demonstration before CMJ and the ability for participants to perform practice jumps? Report

Thank you very much for your comment. Yes, a week before the measurements all participants had a familiarisation with the different tests and technologies. At that time they were able to practice the CMJ jump. Also prior to the test, the principal investigator gave a demonstration to the participants. The familiarisation is included in the "design" section.

Report the sample size calculations as they are in this paper (the picture attached can not be opened): 10.3390/biology10111199

Thank you very much for your comment. The sample size was justified by a priori power analysis in WebPower system with a type I error rate of 0.05 and 91% statistical power. Overall, the analysis indicated that 10 participants per group (total 40) are sufficient to observe significant large-sized acute effects (Cohen’s d = 0.80).

Add the time of the measurements in the text.

They have been added to the text.

What was the warp up before each session? Report

The warm-up before the session was 15 minutes. They ran 2 laps of the pitch. Then 6-8 minutes of joint mobility (ankles, knees, hips, arms, shoulders, and neck) and between 3 and 5 sprints with progressively increasing speed and changes of direction. Finally, 5 minutes of ball touch in pairs

Limitations section - was done only on males - therefore the results can not be generalised to all children.

Thank you very much for your suggestion. It has been added to the limitations section.

I would also try to add gender specificity in the title so it is not misleading. Please amend.

They have been added to the title.

Reviewer 3 Report

Despite changes, this manuscript still presents serious problems. Some are itemized below.

1. The experimental design is confused: has the control group a real role? Being composed of "sedentary" children compared with children practising regular sporting activity for at least one year, better body composition/physical fitness is obviously expected in the latter; following the 12-week soccer training period such a finding is even more obvious. As a consequence, the results of these comparisons are not dealt with in the Discussion.

2. Now we know that the soccer players were equally divided in the U10 (n=10) and U12 (n=10) categories with a total of 4 forwards, 8 midfielders, and 8 defenders. However, in Table 3 and Fig.1 results are broken down by playing position separately for the U10 and U12 categories. This implies that a maximum number of 2 forwards per category were in analysis. Does this make sense?

3. Results of physical fitness tests are not discussed.

In my opinion the authors introduced in the manuscript much redundant data instead of concentrating on the core results i.e., the GPS data during the 12-week training period.

Author Response

Despite changes, this manuscript still presents serious problems. Some are itemized below.

1. The experimental design is confused: has the control group a real role? Being composed of "sedentary" children compared with children practising regular sporting activity for at least one year, better body composition/physical fitness is obviously expected in the latter; following the 12-week soccer training period such a finding is even more obvious. As a consequence, the results of these comparisons are not dealt with in the Discussion.

Thank you very much for your comment. The objective of the control group in this research is to check the differences in the variables of body composition and physical fitness with respect to the football group. These differences are obvious in the baseline measurement, but we want to check whether after 12 weeks of football training it positively affects the development of the variables analysed and whether these differences increase or decrease with respect to the sedentary control group.

A large number of studies use a control group to test the differences after an intervention and specifically in football, children's age and body composition, there is a study cited several times that uses a football group with at least 3 years of practice, compared with a sedentary control group that only performs physical education classes at school. Therefore, we have included the comparison between the two groups in the discussion.

Zouch, M., Jaffré, C., Thomas, T., Frère, D., Courteix, D., Vico, L., & Alexandre, C. (2008). Long-term soccer practice increases bone mineral content gain in prepubescent boys. Joint Bone Spine, 75(1), 41-49.

 

2. Now we know that the soccer players were equally divided in the U10 (n=10) and U12 (n=10) categories with a total of 4 forwards, 8 midfielders, and 8 defenders. However, in Table 3 and Fig.1 results are broken down by playing position separately for the U10 and U12 categories. This implies that a maximum number of 2 forwards per category were in analysis. Does this make sense?

Thank you very much for your comment. The analysis has been done by position of the players because in the literature there is very little data that divides it by position in U10 and U12 categories. As for the number of strikers, this is the reality we find in these categories, where they play 8-a-side football. Statistically it is not powerful, but it is the reality in these age groups. A previous study on the physical demands in the U19 category carried out an analysis by playing positions and obtained data on 3 wingers. However, the main objective of the study is the comparison of body composition, where we unify the positions and analyse the U10 and U12 age categories where the sample is larger.

 

Borghi, S., Colombo, D., La Torre, A., Banfi, G., Bonato, M., & Vitale, J. A. (2021). Differences in GPS variables according to playing formations and playing positions in U19 male soccer players. Research in Sports Medicine, 29(3), 225-239.

3. Results of physical fitness tests are not discussed.

Thank you very much for your suggestion. The results of the physical fitness tests have been discussed in the manuscript.

 

Reviewer 4 Report

Dear Authors,

Thank you for addressing my concerns and sugestions.

Author Response

Thank you very much for your suggestions, we really appreciate your help and support to improve the manuscript.

Best regards

Round 3

Reviewer 3 Report

The revised manuscript presents slight changes addressing my previous criticisms to a very limited extent.