Quarterly Percentual Change in Height, Weight, Body Fat and Muscle Mass in Young Football Players of Different Categories

Round 1

Reviewer 1 Report

Comments

Introduction

It seems to me that it is correct but it should have a more structured logical order to understand the logic of your study more precisely. I propose that you order the ideas in this way.

Paragraph 1: General aspects of the study variables

Paragraph 2: Applications of the variables to sports performance according to age and season

Paragraph 3: Justification of the study and statement of the problem

Paragraph 4: Study objectives and hypotheses.

Although this structure can be perceived, the justification of the study and the research problem must be detailed more precisely, since it cannot be evident according to what has been read.

Methodology

Participants

It is not explicit whether informed consent and assent was used in the case of minors, both for the guardians and also the approval of an ethics committee and the Helsinki recommendations.

Procedures

It is necessary to provide the greatest amount of explicit information so that this same process can be replicated in another study, therefore I suggest incorporating a figure that demonstrates the step by step of your study. You can take as an example figure 1 from the study García-Pinillos, F., Bujalance-Moreno, P., Lago-Fuentes, C., Ruiz-Alias, S. A., Domínguez-Azpíroz, I., Mecías-Calvo, M., & Ramirez-Campillo, R. (2021). Effects of the menstrual cycle on jumping, sprinting and force-velocity profiling in resistance-trained women: A preliminary study. International Journal of Environmental Research and Public Health, 18(9), 1–10. https://doi.org/10.3390/ijerph18094830.

It is necessary to incorporate a descriptive table of the types of training that the players underwent, perhaps this type of training could evidently explain in part the CC changes and another part the maturational development. How could I justify these changes?

Discussion

Is it necessary to incorporate major limitations of the study, for example the reliability and validity of the data provided, or is the measurement carried out a goldstander measurement, etc.?

Conclusions

There is a need to incorporate a greater number of practical applications for the sports community, that is, what could this information be used for by the group of scientists and technica

Author Response

Dear Reviewer 1:

Thank you very much for your comments which undoubtedly improve the manuscript.

The introduction has been reordered to include three new paragraphs to focus on general aspects of the study variables, the rationale for the study, and the objectives and hypotheses.

The "Participants" section has been rewritten to specifically include informed consent, assent in the case of minors, ethics committee approval and respect for the Declaration of Helsinki.

In the Procedures section we have incorporated figure 1, which demonstrates the step-by-step study protocol.

Tables 2 and 3 specify the Typical training week for each age group.

In the discussion the limitations of the study have been expanded to include the validity and reliability of the measurement instruments as well as the lack of nutritional follow-up.

Thank you very much for your interest and we hope that these amendments will be in line with your review.

Author Response File: Author Response.pdf

Reviewer 2 Report

Thank you first for the opportunity to review this work. In an effort to synthesize, I would like to make exact references to the following aspects:

1. I appreciate the accuracy of the approach of indicating the procedure for making the measurements and especially the conditions for making them indicated in Materials and Methods. However, I think that there was an excess of zeal by mentioning the fact that it was explicitly stated that the participants had to come with an empty bowel. I don't think they were given an enema or were medicated to get to that state. Also, it is indicated that no alcohol was consumed...at 13 years old? football players, I don't think it's a normal thing at this age. I think that these aspects of detail should be eliminated or the portions of the text in question should be rephrased.

2. I ask the authors to verify the data regarding the muscle mass. It is known that during growth spurts (in height) in children, the muscle mass decreases due to the elongation of the muscle fiber. I don't see such correlations from the figures from Results.

Author Response

Dear Reviewer 2:

Thank you very much for your appreciation of the accuracy of the measurement procedure. Regarding the measurement conditions, we followed the protocol of Yamada et al (2017) (28) to determine the appendicular skeletal muscle mass in which it was specifically recommended to suggest that participants come to the measurement session with an empty bladder and bowel, within the participants' ability and understanding.  An enema was not, of course, administered, but participants were asked to go to the bathroom before the measurements were taken. All participants were also asked to refrain from drinking alcohol. Unfortunately, there are some studies and empirical observations that indicate that the initiation of alcohol consumption is becoming more frequent every year and, in our environment, the average age of initiation in different drinking behaviours is already 12-16 years old (García-García, E., Martínez-Gimeno, M. L., Benítez-Andrades, J. A., Miranda-Gómez, J., Zapata-Cornejo, E. D. D., & Escobar-Aguilar, G. (2021, February). Substance use and addictive behavior in Spanish adolescents in secondary school. In Healthcare; 9(2). 186).  However, the lifestyle of the participants in the football academy is thought to prevent substance use.

Table 1 shows the absolute data (means and SD) of the participants' muscle mass according to age, while table 4 shows the Results of the Repeated Measures Two Way ANOVA among others for muscle mass.

Thank you very much for your interest and we hope that these amendments will be in line with your review.

Author Response File: Author Response.pdf

Reviewer 3 Report

I would like to commend the authors for their work with such a large sample. Surely, the work holds great value, but its presentation needs a complete overhaul. A reader who is not well-versed in this topic but would like to delve into it would be left confused after reading this paper. For example, the introduction should build that theoretical framework on which the research is based. It doesn't occur in your paper. Therefore, it's not clear why certain choices were made. For example, why did you choose the quarter? Additionally, the data analysis section is missing, which in a scientific paper details how the data collected during the study were processed, analyzed, and interpreted to obtain meaningful and coherent results with the research objectives. This section is essential to ensure transparency and reproducibility of the study, allowing readers to assess the validity and reliability of the presented conclusions. The effect size for RM ANOVA has not been calculated, making it difficult to understand the extent of the recorded differences. The bibliography at the end of the paper needs to be revised according to the journal's requirements. My advice is to rewrite the paper and have it reviewed by someone in your research group who has never participated in the study so that you can identify any parts that continue to be confusing.

P.S. I don't understand why you use numbers in parentheses in the abstract. If it's not required by the journal, I wouldn't reuse this structure.

Author Response

Dear Reviewer 3:

Thank you very much for your comments. The manuscript has been reviewed by a research colleague (FTF-G) who is not involved in the authorship of the paper.

Following his indications, the parentheses in the abstract have been removed.

To clarify the manuscript we have included some concepts in the introduction regarding the theoretical framework of the paper.

The data analysis section has been expanded to include tables 1, 2 and 3 in which Longitudinal descriptive analysis (Average and Standard Deviation) is performed. Table 4 shows the Results of the Repeated Measures Two Way ANOVA including F, Df and P value.

References have been checked according to Vacouver standards.

Thank you very much for your interest and we hope that these amendments will be in line with your review.

Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

I would like to congratulate with the authors on the improvements made to the paper. However, there are two issues that need to be addressed. The first relates to the coherence between the abstract and the introduction. In the abstract you state that "the purpose of this study was to compare the percentages of quarterly change for each of the variables analysed (height, weight, body fat percentage, and muscle mass)." Then, when discussing the results, you mention BC which is also the subject discussed in the introduction. We know that the variables you are discussing are related to BC, but you should explicitly state it to avoid confusion. In summary, it would be advisable to add the term "body composition" in the first sentence of the abstract and, consequently, provide a clear and concise definition of BC in the introduction, focusing on the variables that allow its evaluation. This way, the abstract will be truly connected to the introduction. The second issue pertains to the "data analysis" section. The manuscript I have received and read is lacking the "data analysis" section. This must be included and written coherently with what was discussed in the introduction. The coherence between the introduction and the data analysis in a scientific article is crucial to ensure the validity and clarity of the research. Data analysis should reflect the context and objectives outlined in the introduction, guiding the reader through the research process and emphasizing the robustness of the results.

Author Response

Dear reviewer: Thank you very much for your congratulations for the changes made in Round 1.

- Following your recommendations we have modified the abstract to be more coherent with the introduction by including the term Body Composition in the first sentence of the abstract.

- We have also included the section on Data Analysis which we believe is more connected to the introduction and methodology. In this way we believe we achieve greater validity and clarity in the presentation of the results. In this section we have tried to set out both the context of the research and the way in which the objectives set out at the beginning of the research were achieved. With the data analysis carried out, we believe that we can better orientate those who may be interested in this type of research by demonstrating a greater solidity in the results obtained.  As a result, we have modified the headings of the figures previously carried out and have included figure 6 in which the percentage changes of each variable are represented.

In this sense, we have felt it necessary to partially modify the title of the manuscript as well as part of the discussion in order to explain the results obtained in more detail.

Thank you very much for your interest.

The authors.

Author Response File: Author Response.pdf