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Dear Authors,
Thank you and congratulations on your work during the review process, addressing all of the reviewers' comments.
Best wishes for the continued development of your good work.
Best regards,
[# PeerJ Staff Note - this decision was reviewed and approved by Mike Climstein, a PeerJ Section Editor covering this Section #]
The areas previously highlighted have been well addressed by the authors in this revision.
The areas previously highlighted have been well addressed by the authors in this revision.
The areas previously highlighted have been well addressed by the authors in this revision.
The areas previously highlighted have been well addressed by the authors in this revision.
The manuscript has been revised and improved following all the suggestions provided by the reviewers. Particular attention has been given to enhancing the clarity of the text, the quality of the English, the updating of the theoretical background, and the proper presentation of figures, tables, and data.
The manuscript has been revised and improved according to the reviewers’ suggestions regarding the experimental design.
The manuscript has been revised and improvements have been made to strengthen the validity of the findings. The justification of the study and its contribution to the literature have been clarified. All data have been checked to ensure they are complete and supported by appropriate statistical analyses.
The conclusions have been adjusted to ensure they are clearly connected to the research question and limited strictly to the results obtained. These modifications enhance the clarity and robustness of the study’s findings.
Dear Authors,
Please revise the manuscript considering the suggestions provided by the reviewers.
Thank you.
Best regards.
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Generally, the article is well-written, but there are some areas for improvement. A hypothesis is not mentioned until the conclusion, which should appear far earlier.
I recommend that “weight” be replaced with “body mass” throughout the manuscript. There are technical distinctions between the two, and it is mass that is measured in kilograms rather than weight.
The experimental design is sound for investigating the relationship between age category and performance in the soccer-specific tests. However, the authors imply that this suggests a link between physical maturity and performance, which cannot be concluded based on the methodology used. The authors first measured anthropometry rather than maturation. Secondly, the statistical analysis does not investigate the relationship between anthropometry and performance, so it cannot be concluded that physical differences impact performance purely based on age categories. Whilst this is likely given the differences between age groups in mass, height, etc, to make this conclusion, the authors must statistically investigate the relationship between these variables (mass, height, BMI) and performance.
As above, if the findings are purely referring to the age category, then the results are sound. However, the terminology of the study should be adapted to reflect this rather than refer to the impact of physical maturation. If the authors wish to report the link between physical differences (in height, mass, etc), then this needs to be presented with statistical analysis. Currently, it is only possible to state that there are differences in performance based on age group, and there is the implication that this relates to the anthropometric differences reported separately.
Section-specific comments:
General comments:
I recommend that “weight” be replaced with “body mass” throughout the manuscript. There are technical distinctions between the two, and it is mass that is measured in kilograms rather than weight.
Abstract
Line 32: If results were not statistically significant, I suggest not referring to “differences” at all. This also applies to the
Line 34: The term “physical maturation” does not seem appropriate to me, as this implies that maturation has been quantified in the present study. Although older age was associated with COD, this does not necessarily mean a greater degree of physical maturity. Likewise, even with players taller/heavier, this also does not necessarily equate to greater physical maturity.
I also suggest referring to “chronological age” here instead, and also that this is “associated” or “related” to COD performance, rather than enhanced due to the lack of causal evidence.
Introduction
Line 41: May I suggest the small change to replace “or” with “and” when referring to the match activities. Using “or” could be interpreted that players perform one activity or another, when in fact they will perform all of those listed.
Line 53: I would suggest caution when using terms such as “developmental stages”, as this implies biological maturation rather than what is assessed in the current study (anthropometry and age).
Lines 81-95: As this section describes COD and a test used for COD assessment, it would be more appropriate if moved earlier (after line 72). This would ensure the introduction of each quality (COD and RSA) is linked with a description of how it is tested.
At the end of the introduction, it is not clear what the hypothesis was. If referring to this within the discussion, then the hypothesis should be stated before the methodology.
Materials and methods
Line 110: Please, can the authors provide more information on the professional soccer clubs? This does not need to identify the clubs, but should at least detail their location, some indication of standard, and whether the players were registered as first team players or with the club’s academy.
Lines 132-133: Please can the authors detail whether COD/RSA qualities were directly trained during the training period before testing? This could influence ability and performance in COD/RSA tests, so this information would be beneficial to the manuscript.
Line 137: Were all testing sessions conducted at the same time of day? Please specify.
Line 161: Please replace “weight” with “mass”. I would also suggest re-ordering the described variables so that BMI comes last, as BMI cannot be calculated without first collecting height and mass.
Line 171-176: Could the authors provide more description of the NMAT? Currently, it is only described as a “25-m agility run”, which is quite vague. This contrasts with the following paragraph describing the Bangsbo RSA test in much greater detail.
Results
In general, the results could be described more concisely. There is some text that strays toward interpretation, e.g., “indicating that…”. In my opinion, this is not required and makes the results longer than they should be.
I would recommend separating the anthropometric data from the results of the performance tests. It would be useful to visualize the performance test data using a figure, rather than in a table.
Line 232: Rather than referring to “a lower performance”, I recommend more specific and descriptive terminology, such as “slower performance”.
Discussion
Line 271-275: I am not sure the detailed discussion of body composition is fully relevant, as body composition has not been reported in the study.
Line 280: It is not explicitly clear to me how age-related differences are indicative of physical maturity and/or neuromuscular adaptation. Neither of these has been measured in this study. It cannot be assumed that older age and greater weight/height are the same as physical maturity, which is a distinct construct in itself. A shorter player is not necessarily any less physically mature than a taller player if both have achieved their full stature. Likewise, a heavier player is not necessarily more physically mature than a lighter player.
Line 285: “Physical maturation” should be replaced with “somatic stature” or “anthropometry” here, for the reasons outlined above.
Line 287: “Growth” here is also incorrectly used. To measure growth, these players would have to be measured multiple times across a longitudinal period. The current study has investigated anthropometric differences between age categories, rather than growth.
Line 303: I am not sure it can be said that these findings suggest the influence of neuromuscular maturation, as there is no data presented to demonstrate differences in the age categories in neuromuscular capability. There are only differences presented in soccer-specific test performance. In the next few lines, the authors state that strength and power are limitations; therefore, the text around neuromuscular maturation should be modified.
Conclusion
Line 318: This is the first mention of the hypothesis. It should be stated at the end of the introduction and revisited at the start of the discussion when summarising the key findings.
Line 321: I don’t agree that this study suggests physical maturation enhances COD ability. Firstly, this would be better described as “age-related anthropometric differences” as maturation is a different construct that has not been measured. Second, the statistical analysis has only investigated the relationship between age category and performance in the soccer-specific tests, so at most, this can only be described as a relationship between age category and performance. To investigate the impact of anthropometry (or physical differences), the authors would need to run statistical tests assessing the relationship of mass/height/BMI with performance in these tests, which is not presented.
The manuscript is generally well structured and addresses a relevant topic in sports performance analysis. However, there are several minor issues related to formatting, consistency, and English style that should be corrected to improve overall readability and presentation.
Line 23: Please review the standard deviation of height. The reported value (172 ± 0.08 cm) appears to contain a unit error; it was likely intended as 1.72 ± 0.08 m (equivalent to 172 ± 8 cm). A deviation of 0.08 cm is not plausible.
Lines 49–50: Formatting error
Line 91: Add a space after the year in the citation (2001)demonstrated → (2001) demonstrated).
Line 110: The sentence “Seventy-two male soccer players participated…” repeats the verb participated twice. Please correct to avoid redundancy.
Line 161: The acronym BMI appears before being defined; the definition only appears later (line 168). Define it at first mention.
Line 275: The reference ESPADA appears entirely in uppercase. Adjust to match the standard reference format used throughout.
Line 315: In this section, the abbreviations COD (change of direction) and RSA (repeated sprint ability) are explained again, even though they were already defined earlier. It is not necessary to redefine them in the conclusions; simply using the abbreviations would improve flow and avoid redundancy.
Table 1: Ensure consistency in the use of decimal places. Some values are shown with three decimals (e.g., 0.018) and others with two (e.g., 0.003). Additionally, there is an inconsistency in the decimal notation itself: in some cases, “0.08” is used, and in others “.08”. Please unify the style (preferably with a leading zero, e.g., 0.08).
The experimental design is appropriate for the stated aims, and the authors provide adequate methodological detail. Nonetheless, a few clarifications and corrections are required:
Line 212: There is a misinterpretation of the effect size (ES). The manuscript states (p = 0.01, ES = 0.14, moderate), but according to Hopkins et al. (2009) —which the authors themselves cite— a value of 0.14 corresponds to a trivial, not a moderate, effect. This is likely a typographical error (perhaps 1.14, which would indeed be moderate). Please review the calculations and ensure that the reported effect sizes and qualitative interpretations (trivial, small, moderate, large, etc.) are consistent.
Line 242: Review the notation and reported values of η² (eta squared), as some symbols appear corrupted or incorrectly formatted.
Clarify that the height and weight values are expressed in the correct units (1.72 ± 0.08 m instead of 172 ± 0.08 cm), as this affects the validity of anthropometric comparisons.
Ensure that the procedures for COD and RSA tests specify whether the “with” and “without ball” conditions were randomized or counterbalanced to minimize order effects.
The statistical analysis appears sound overall, but several aspects require careful review to ensure internal validity:
Check the correctness of the effect size calculations and their classification according to Hopkins et al. (2009).
Verify that η² (partial eta squared) and p-values are presented with consistent formatting and decimal precision.
Confirm that reported p = 1.00 values (e.g., in group comparisons) are accurate after Bonferroni correction, or replace with p > 0.05 (n.s.) for clarity.
The discussion would benefit from quantitative comparisons with similar studies, presenting actual mean values or differences reported in previous literature. This would strengthen the interpretation and contextualization of findings.
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