Review Reports - What Differentiates Elite, Sub-Elite, and Amateur Young Soccer Players? A Comparative Analysis of Match-Play Locomotor Demands

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript addresses a highly relevant and practically valuable topic within youth soccer development by investigating how match-play locomotor demands vary across different competitive levels and exploring how these differences might inform talent identification processes. A notable strength of this research is its high degree of methodological standardization, as all participating players belonged to the same club, utilized the same tactical formation, and operated under a unified playing philosophy. However, before the manuscript can be considered for publication, several critical methodological, statistical, and structural issues must be thoroughly addressed.
The most significant methodological concern is a substantial confounding variable related to participants' characteristics. The elite group is chronologically older and biologically more mature than the amateur group, with the latter still performing before their peak height velocity, whereas the elite players have already surpassed it. Because of this developmental gap, the study is not merely comparing competitive standards; it is inherently comparing different biological and developmental stages. Consequently, the finding that superior sprint capacities characterize elite status might simply be an artifact of advanced biological maturity rather than football-specific excellence. The authors must statistically control for this maturity gap or discuss it extensively as a primary limitation to prevent misleading conclusions about talent selection.
Furthermore, there is a prominent disconnect between the stated objectives and the actual data presented. In the introduction, the authors explicitly state that the study aims to examine the relationships between locomotor demands, physical fitness, and tactical behavior. Despite this clear promise, the manuscript contains no tactical performance indicators, positional tracking data, or team centroid metrics. Additionally, physical fitness test results are never correlated with the match-play GPS data. If tactical behavior was not analyzed, all references to it must be removed from the study's aims.
The presentation of the results also suffers from severe omissions that compromise the report's transparency. Multiple tables feature completely blank cells where critical data points should be. Specifically, the entire set of physical fitness test results (including anaerobic capacity, linear sprinting, change-of-direction speed, and repeated-sprint ability) is missing for the elite group. Similarly, certain speed zone distances, corresponding statistical significance levels, and effect sizes for the amateur cohort are absent from the subsequent analysis. These omissions must be corrected by fully populating the data sets.
Finally, the text requires meticulous proofreading and structural refining. The statistical nomenclature is inconsistent, frequently alternating between different symbols to denote effect sizes, and several qualitative descriptors do not align with the actual magnitude of the statistical effects. The discussion section is marred by excessive verbatim repetition across consecutive pages, particularly when the authors describe the raincloud plots and the zero-meter sprint outputs of the lower-tier groups. There are also several typographical errors, including a spelling mistake in the main title, missing closing parentheses in variable definitions, and incorrect cross-references that cite tables that do not match the locations of the discussed metrics. Streamlining the discussion and correcting these editorial flaws will greatly enhance the manuscript's scientific rigor and readability.

Author Response

Reviewer 1.

Comment 1. Biological maturation as a potential confounding factor

Thank you for highlighting this important issue. We agree that differences in biological maturation may have influenced the locomotor differences observed among groups. After careful consideration, we decided to retain the original between-group analysis, as the aim was to compare the actual locomotor profiles of players competing at three competitive levels within the same club structure. Nevertheless, we acknowledge that competitive level and maturation cannot be independently disentangled in the present design. Therefore, biological maturation is now explicitly addressed as a major limitation, and the interpretation of high-speed running, sprint, and acceleration–deceleration outcomes has been moderated throughout the Discussion and Conclusions. We also recommend maturity-matched and longitudinal designs for future studies.

Comment 2. tactical behaviour y physical fitness

hank you for identifying this inconsistency. We agree that tactical behaviour was not directly assessed and should therefore not have been included in the study objective. We have removed references suggesting that tactical performance was evaluated and revised the objective accordingly.

Comment 3. Missing physical fitness data for the elite group

Thank you for allowing us to clarify this issue. The values for the elite group were not accidentally omitted. Due to logistical constraints and limited access to elite-team players, the Yo-Yo IR1, 10-m sprint, 505 COD, and RSA tests could not be administered to this group. Table 1 has therefore been revised by replacing “–” with “NA (Not assessed)”, and an explanatory note has been added. The Methods and Limitations sections have also been revised to clarify this issue. These variables were not used to draw comparisons across all three competitive levels.

Comment 4. Statistical, structural, and editorial issues

Thank you for this careful assessment. We agree that several statistical, typographical, Thank you for identifying these inconsistencies. The manuscript has been thoroughly revised to standardize statistical notation, effect-size reporting (ω²), p-values, units, decimal notation, and post-hoc comparisons. Effect-size descriptors and statistical values have also been cross-checked and corrected where necessary. In addition, table and figure cross-references, typographical errors, and variable definitions have been corrected. Duplicated passages in the Results and Discussion, particularly those concerning the raincloud plots and highest-speed zones, have also been removed to improve clarity and readability.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The article “What Differentiates Elite, Sub-Elite, and Amateur Young Soccer Players? An Integrated Analysis of Locomotor Demands and Talent Identification” aims to compare the locomotor demands among three teams at different competitive levels within the same age group and to examine the relationships between locomotor demands, physical fitness, and tactical behavior. This is an original article with the potential to contribute to the future design of physical conditioning and tactical training programs for sports teams.

An introduction to the factors that influence performance in soccer, highlighting how these factors affect tactical and physical ability within the sport. Subsequently, existing findings regarding the performance of professional and younger athletes. Furthermore, the authors highlight the influence of variables such as age, position on the field, competitive level, team composition, and the athletic level of opposing teams as significant factors. They also present scientific data on the impact of athletes’ experience on tactical outcomes.

Based on the theoretical framework and the current state of the evidence, the authors highlight the existing scientific gap (few studies on the combined influence of locomotor demands, physical conditioning, and tactical behavior), so that the combined contribution to player performance and talent identification in youth soccer can be better understood.

Therefore, it is important for the authors to explore this issue in greater depth in this article, including additional paragraphs on what the literature reveals about the impact of the level of competition on physical performance, as well as another that addresses its impact on tactical performance.

In a follow-up study, it would be appropriate to expand on this issue by including a section discussing what the literature reveals about the impact of competition level on physical performance and another section addressing its impact on tactical performance.

The methodology, results, discussion, and conclusion are well presented; in my assessment, no changes are needed. Therefore, we recommend approval with minor corrections.

I appreciate the opportunity to review the article and am available to provide further clarification.

Author Response

Reviewer 2.

The methodology, results, discussion, and conclusion are well presented; in my assessment, no changes are needed. Therefore, we recommend approval with minor corrections.

I appreciate the opportunity to review the article and am available to provide further clarification.

Comment 1. Competitive level, physical performance, and tactical performance

Thank you very much for the positive assessment of our manuscript and for this valuable suggestion. We agree that further consideration of the influence of competitive level on physical and tactical performance strengthens the theoretical framework of the study.

Accordingly, we have expanded the Introduction to provide additional evidence regarding the influence of competitive level on physical and locomotor performance, particularly high-intensity actions. We have also expanded the discussion of tactical performance, including perceptual ability, decision-making, positioning, and collective coordination.

As tactical behaviour was not directly assessed in the present study, we have clarified that it represents a relevant contextual factor rather than an outcome variable. We have also identified the integration of tactical, positional, and locomotor measures as an important direction for future research.

We thank the reviewer for this suggestion, which has helped us strengthen and clarify the Introduction.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

Thank you for the opportunity to read this manuscript. I found the topic both interesting and practically relevant. The paper poses a valuable question. This manuscript addresses a practically relevant topic by comparing match locomotor demands among elite, sub-elite, and amateur youth soccer players from the same club.

Title

The title is generally relevant, but the spelling error in “diffentiates” should be corrected to “differentiates.” Please also use “sub-elite” consistently.

The phrase “talent identification” may be too strong because the study compares existing teams cross-sectionally and does not examine later selection, progression, or future performance. A more cautious title focusing on locomotor differences across competitive levels may better reflect the actual design.

Abstract

The abstract is informative but currently too long and includes several interpretations that are not directly supported by the measurements. For example, the claim that sub-elite players showed “lower tactical organization” and that elite players performed more “purposeful and efficient” movements cannot be confirmed because tactical behavior was not objectively assessed.

Please briefly report the observational cross-sectional design, participant characteristics, number of matches, GPS procedures, and main statistical analyses. The conclusion should also be softened from talent identification claims to the potential usefulness of high-speed variables in profiling youth players.

Introduction

The introduction provides a useful overview of physical fitness, locomotor demands, the level of competition and tactical factors. However, the final objective states that the study examines the relationships between locomotor demands, physical fitness and tactical behaviour. However, the results only compare locomotor variables across three groups, with no tactical measure or relationship analysis presented. Either revise the objective to match the analyses conducted, or provide the missing analyses.

The research gap should also be stated more clearly. Currently, the introduction discusses many determinants of match performance, but does not adequately explain how this study builds upon previous comparisons of youth players at different competitive levels.

Participants

The most important concern is that the three groups differ substantially in age, maturity offset, height, and body mass. The amateur group is younger, approximately 1.30 years before peak height velocity, whereas the elite group is older and already past peak height velocity. Therefore, the observed differences in high-speed and sprint performance may reflect maturation rather than competitive level alone.

Please statistically control for age and biological maturation, for example through ANCOVA or another appropriate model, or substantially revise the interpretation and acknowledge that competitive level and maturation cannot be separated in the current design.

Please also clarify whether all participants were male, how many match observations were available for each player, and how missing observations were handled. The statement that the dataset was “complete and representative” is difficult to reconcile with the exclusion of data due to injuries, absences, or non-selection.

Procedures and Physical Fitness Tests

The testing procedures require clearer organization. Please report the precise testing order, number of trials, recovery periods, familiarization procedures, and whether environmental and time-of-day conditions were standardized across teams.

Table 1 contains substantial missing data for the elite group in the Yo-Yo test, 10 m sprint, COD, and RSA tests. Since the manuscript describes an “integrated analysis” involving physical fitness, the absence of these data should be explained. If physical fitness was not compared across all three groups, these variables should not be presented as a central component of the study.

Some numerical values also require verification. For example, the amateur RSA total time of 334.79 s appears inconsistent with the sub-elite value of 30.97 s and may be a typographical or calculation error.

Match and GPS Data

Please clarify the actual unit of analysis. Ten matches were examined, but individual players may have contributed data from several matches. It is not clear whether the analyses used each match observation independently or each player’s average across matches. If repeated match observations were analyzed as independent cases, the independence assumption is violated, and a multilevel or repeated-measures model would be more appropriate.

Although match duration, formation, and substitution rules were similar, other important contextual factors were not controlled, including playing position, opponent quality, match location, score status, ball possession, and time played. These variables may substantially influence locomotor demands and should be controlled where possible or acknowledged as limitations.

The definitions of acceleration and deceleration events also need clarification. Counts of approximately 3,600–4,300 events per player appear unusually high. Please explain the event-detection algorithm, minimum duration, and threshold used by the WIMU software.

Statistical Analysis

The statistical section requires substantial revision. With only 55 players and a large number of dependent variables, several MANOVAs may be unstable. Please report the assumptions of multivariate normality, homogeneity of covariance matrices, independence, and multicollinearity among dependent variables.

Please also explain how multiple testing was controlled across the numerous MANOVAs, ANOVAs, and post hoc comparisons. The current approach creates a considerable risk of Type I error.

The manuscript states that omega-squared values were calculated “from MANOVA,” although the reported values appear to correspond to individual univariate ANOVAs. This wording should be corrected.

For highly zero-inflated variables, particularly distances above 27 or 30 km·h⁻¹, standard ANOVA assumptions may not be met. A non-parametric or zero-inflated analytical approach should be considered.

Results

Several statistical inconsistencies should be corrected carefully. Most importantly, the impact MANOVA is reported as p = 0.01 but is interpreted as non-significant. This is a serious contradiction and should be verified.

In Table 5, maximal speed has ω² = 0.29, whereas the text reports ω² = 0.19. All table and narrative values should be cross-checked.

The manuscript sometimes describes non-significant comparisons as meaningful “small” or “moderate differences.” Effect sizes may be reported, but the text should clearly distinguish between statistically significant and non-significant findings. Confidence intervals for effect sizes would also improve interpretation.

There is also duplicated text in the distance results, and references to “Figure X” remain in the manuscript. These issues should be corrected.

Discussion

The discussion provides useful comparisons with previous studies, particularly regarding absolute versus relative speed thresholds. However, several interpretations go beyond the data. Statements that amateur and sub-elite players have “lower tactical structure,” rely on “reactive corrective movements,” or that elite players “move better” and act with greater tactical purpose are speculative because tactical behavior was not measured.

The discussion should give much greater attention to biological maturation. Given the large maturity differences among groups, it is not possible to conclude confidently that high-speed performance distinguishes competitive level independently of developmental status.

The manuscript should also avoid presenting high-speed variables as validated talent-identification markers. The findings show cross-sectional group differences, but they do not demonstrate predictive validity for future talent development or selection.

Limitations

The limitations section needs to be expanded. It should explicitly address the small sample from one club, unequal numbers of matches, repeated observations, lack of positional and contextual control, age and maturation confounding, missing fitness data for the elite group, and the cross-sectional design.

The current limitation discussion focuses mainly on the weaknesses of load metrics rather than the limitations of the study design itself.

Conclusion

The conclusion should be more cautious. Phrases such as “competitive levels are primarily determined by” and “robust discriminators for talent identification” imply stronger evidence than the design provides.

A more appropriate conclusion would be that absolute high-speed running and maximal speed differed among the three teams, but these findings should be interpreted in light of substantial age and maturation differences and require confirmation in larger, maturation-matched longitudinal studies.

The study has practical potential and includes valuable match-derived GPS data. However, the maturation confounding, unclear unit of analysis, inconsistencies in the statistical results, and unsupported tactical and talent-identification interpretations are substantive concerns. I therefore recommend major revision before the manuscript is reconsidered.

Author Response

Reviewer 3

Comment 1. Title

The title is generally relevant, but the spelling error in “diffentiates” should be corrected to “differentiates.” Please also use “sub-elite” consistently.

Thank you for this suggestion. We agree that the term “talent identification” in the original title could imply predictive validity beyond the scope of our cross-sectional design. Therefore, we corrected the spelling error, standardized the use of “sub-elite,” and revised the title to more accurately reflect the comparative nature of the study.

The final title was: What Differentiates Elite, Sub-Elite, and Amateur Young Soccer Players? A Comparative Analysis of Match-Play Locomotor Demands

Comment 2. Abstract

The abstract was updated correspondingly

Comment 3. Introduction

Thank you very much. The introduction was updated and improved exponentially and correspondinlgy

Comment 4. Participants

Thank you for raising this important methodological concern. We fully agree that chronological age and biological maturation represent relevant factors when interpreting locomotor performance in youth soccer. As the reviewer correctly notes, the amateur group was predominantly pre-PHV, whereas the elite group was, on average, post-PHV. After careful consideration, we have decided to retain the original between-group analytical approach rather than statistically adjusting the locomotor outcomes for maturity offset. The primary purpose of the present study was descriptive and comparative: to characterize the match-play locomotor profiles of three naturally occurring competitive squads within the same club structure. In this context, competitive level, chronological age, and maturation are intertwined characteristics of the groups being compared. Importantly, we acknowledge that this analytical approach does not allow the independent effect of competitive level to be separated from biological maturation. We have therefore substantially revised the interpretation of the findings rather than attributing the observed differences exclusively to competitive standard.

Throughout the Abstract, Discussion, Limitations, and Conclusions, statements implying that high-speed running or maximal sprint performance independently characterize elite status have been moderated. The revised manuscript now explicitly states that the observed differences may reflect the combined influence of competitive level, chronological age, and biological maturation. Biological maturation has also been included as a major study limitation, and we now recommend larger studies using maturity-matched samples and longitudinal designs to disentangle developmental and competitive-level effects.

Comment 5. Procedures and Physical Fitness Tests

Thank. you very much. The information was updated correspondinlgly

Comment 5. Match and GPS Data

Statistical Analysis

Please also explain how multiple testing was controlled across the numerous MANOVAs, ANOVAs, and post hoc comparisons. The current approach creates a considerable risk of Type I error.

The manuscript states that omega-squared values were calculated “from MANOVA,” although the reported values appear to correspond to individual univariate ANOVAs. This wording should be corrected.

The text was updated corresponinlgy

Thank you for raising this important point. We apologize that the unit of analysis was not sufficiently clear in the original manuscript. Individual match observations were not treated as independent cases. For each player, locomotor variables were averaged across the eligible matches in which the player participated, resulting in a single value per player for each variable. Therefore, each player contributed only one observation to the subsequent MANOVA/ANOVA analyses. Accordingly, repeated match observations from the same player were not entered as independent cases, and the statistical analyses were conducted at the player level. We have now clarified this procedure in the Methods section to avoid any ambiguity.

On the other hand, Although several match-related conditions were standardized, including match duration, tactical formation, and substitution rules, other contextual factors such as playing position, opponent quality, match location, score status, and ball possession were not included in the analyses. These factors may influence locomotor demands and should therefore be considered when interpreting the present findings

Results

In Table 5, maximal speed has ω² = 0.29, whereas the text reports ω² = 0.19. All table and narrative values should be cross-checked.

There is also duplicated text in the distance results, and references to “Figure X” remain in the manuscript. These issues should be corrected.

We acknowledge the reviewer’s concern regarding the results. All the results section was updated.

Discussion

We acknowledge the reviewer’s concern regarding the limiations. All the limitations and strengths was updated. In addition, a practical applications sections was added.

Limitations

The current limitation discussion focuses mainly on the weaknesses of load metrics rather than the limitations of the study design itself.

We acknowledge the reviewer’s concern regarding the limiations. All the limitations and strengths was updated. In addition, a practical applications sections was added.

Conclusion

The conclusion was update

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The authors are thanked for their efforts in revising the manuscript and addressing several structural, typographical, and editorial concerns. The manuscript has improved in terms of clarity and overall presentation. However, critical methodological issues raised in the initial review remain unresolved, as the authors relied on narrative limitations rather than applying necessary statistical and structural fixes.
Regarding biological maturation, acknowledging this confounding factor solely in the limitations section is insufficient for a study aiming to compare competitive levels. Because the elite group is chronologically and biologically more mature than the non-elite groups, performance differences cannot be attributed strictly to competitive standard or talent. The authors must either statistically control for biological maturity using an appropriate covariate analysis or reframe the manuscript's scope and title to reflect age- and developmental-stage differences rather than competitive talent identification.
Regarding the incomplete physical fitness data, leaving unassessed tests marked as not applicable in the elite benchmark cohort severely compromises the validity of the comparison. A comparative profile across competitive tiers cannot be effectively drawn when the elite group lacks an entire battery of physical capacity tests. The authors should either remove the incomplete physical fitness variables altogether to focus exclusively on the complete GPS match-play data or restructure the manuscript into separate analytical sections that reflect the available datasets without leaving missing profiles in the main comparison. A second major revision is necessary to resolve these methodological limitations before publication can be considered.

Author Response

Dear Reviewer,

We sincerely thank you for your time, valuable feedback, and constructive criticism of our manuscript. We have taken your methodological concerns very seriously. Instead of relying on narrative limitations, we have executed the definitive statistical and structural modifications you requested.

Below, we detail how each critical point has been fully resolved in this revised version.

Point 1: Statistical Control for Biological Maturation

“Regarding biological maturation, acknowledging this confounding factor solely in the limitations section is insufficient... The authors must either statistically control for biological maturity using an appropriate covariate analysis or reframe the manuscript's scope...”

Response:

We completely agree with this crucial methodological observation. To fully resolve this issue, we have reanalyzed our entire dataset using Multivariate and Univariate Analyses of Covariance (MANCOVA / ANCOVA), incorporating Peak Height Velocity (PHV) as a continuous covariate to control for biological maturation.

Distance, Sprint, and Acceleration/Deceleration Metrics (Tables 3,4 and 5): The ANCOVAs confirmed that even after neutralizing the effect of PHV, the competitive standard exerts a potent, independent influence on physical performance. The elite group still covered significantly greater distances in high-speed categories (>18 km·h⁻¹), very-high-speed running, and absolute sprinting. Furthermore, elite players achieved significantly higher maximal acceleration and deceleration values and covered greater distances within high-intensity acceleration zones demonstrating a genuine neuromuscular superiority independent of biological growth.

Load Metrics (Table 6): Interestingly, changing from ANOVA to ANCOVA filtered the maturational noise, revealing significant main effects of competitive level across multi-planar Player Load These analyses show that elite players accumulate lower structural and mechanical loads, displaying superior biomechanical economy during match-play.

The Results, Table 3,4,5 and 6, and the Discussion section have been rewritten to reflect these rigorous, covariate-adjusted findings and considerations. We have moved from a narrative limitation to an empirical, independent confirmation of the competitive standard effect.

Point 2: Incomplete Physical Fitness Data

“Regarding the incomplete physical fitness data... The authors should either remove the incomplete physical fitness variables altogether to focus exclusively on the complete GPS match-play data or restructure the manuscript...”

Response:
We acknowledge that leaving missing profiles in the benchmark cohort compromised the validity of the comparison. Following your explicit recommendation, we have completely removed the incomplete physical fitness variables (Yo-Yo IR1, 10-m sprint, 505 COD, and RSA) from the main comparative framework. We have only retained the Handgrip, Countermovement Jump (CMJ), and Squat Jump (SJ) tests strictly as baseline descriptive data of the study population.

The study now focuses exclusively and robustly on the complete GPS match-play dataset (locomotor distances, accelerations/decelerations, impacts, and multi-planar body loads), which is fully available and standardized across all three competitive tiers (amateur, sub-elite, and elite.The omitted physical fitness data will be utilized for alternative future research addressing different investigative questionsThis structural fix eliminates any missing profiles and provides a clean, rigorous, and ecologially valid match-play comparison

Author Response File: Author Response.pdf

Round 3

Reviewer 1 Report

Comments and Suggestions for Authors

The authors have made a commendable effort to address the previous reviewers' comments, particularly by re-analyzing the dataset using MANCOVA/ANCOVA with Peak Height Velocity (PHV) as a covariate, and by removing incomplete fitness test data from the primary comparative framework. These adjustments significantly strengthen the scientific rationale of the study.
However, there is a critical discrepancy between the response letter and the updated manuscript text that must be addressed before publication:
1. Methodological Inconsistency in Text and Tables: In the response letter, the authors state that the entire dataset was re-analyzed using MANCOVA/ANCOVA to isolate the independent effect of competitive level while controlling for maturity. However, the manuscript text (e.g., Abstract: "locomotor variables were compared using multivariate and univariate analyses of variance [MANOVA/ANOVA]") and the titles of Tables 4 and 5 still refer to "ANOVA p-values". Please thoroughly revise the text, methods section, abstract, and table headers (Tables 4 and 5) to consistently reflect the ANCOVA/MANCOVA model used.
2. Harmonization of Discussion and Conclusion: In the Abstract and the Discussion (Page 16), the authors state that the findings "cannot be attributed exclusively to competitive level, but may reflect the combined influence of competitive standard and developmental characteristics." This contradicts the response letter, which claims that maturity was statistically controlled for via ANCOVA. If the ANCOVA model successfully controlled for PHV, the conclusions should clearly state that competitive level exerts an independent effect. If biological maturation still confounds the results, the statistical approach and interpretation need further clarification.
3. Table Formatting: Please check the formatting in Table 3.

Author Response

Thank you very much for your support

All the changes were performed and improved exponentially.

Best regards

Author Response File: Author Response.docx