Plyometric Training in Prepubertal Soccer Players: Is It Really Effective for Soccer Performance?

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The authors of this manuscript have presented the analysis of the plyometric training in prepubertal footballers. Thank you for the opportunity to review your manuscript. The study addresses a relevant topic and is overall well-structured. The introduction, results, and discussion sections are generally well-written and informative. However, I would like to raise a few points that require clarification or improvement:

 

INTRODUCTION

The introduction provides a good context about plyometric training in prepubertal footballers

 

METHODS

Participants

Provide more information about the demographic data, the experience and the competitive level.

Plyometric Training Program Details

The methodology lacks important information regarding the plyometric training program. Please clarify:

• When were the plyometric sessions performed — before or after the main training sessions?
• How many times per week were these sessions conducted?
• What was the structure in terms of sets, repetitions, and rest intervals?
  Including these details is essential for reproducibility and for understanding the potential training load applied to the participants.

Statistical Analyses
There appears to be a typographical or conceptual error in the interpretation of Cohen’s d values. You state:
“Effect size (ES) was calculated using Cohen's d and interpreted as small (< 0.20), medium (< 0.50), or large (< 0.80).”
This is inconsistent with standard interpretations. Typically, Cohen’s d is interpreted as:

• Small: 0.2
• Medium: 0.6
• Large: 0.8
  Please revise the thresholds and corresponding interpretations to align with conventional standards or provide justification if a different classification is used.

 

Suggested Literature for Consideration
You may consider citing the following recent systematic review, which discusses strength training variables and their effects on neuromuscular adaptations in prepubertal children:

• Sánchez Pastor, A., García-Sánchez, C., Marquina Nieto, M., & de la Rubia, A. (2023). Influence of Strength Training Variables on Neuromuscular and Morphological Adaptations in Prepubertal Children: A Systematic Review. International Journal of Environmental Research and Public Health, 20(6), 4833. https://doi.org/10.3390/ijerph20064833
  Evaluate whether its inclusion would enrich your discussion on the effectiveness and design of training programs in young populations.

 

Author Response

Reviewer 1:

The authors of this manuscript have presented the analysis of the plyometric training in prepubertal footballers. Thank you for the opportunity to review your manuscript. The study addresses a relevant topic and is overall well-structured. The introduction, results, and discussion sections are generally well-written and informative. However, I would like to raise a few points that require clarification or improvement:

The authors would like to thank the reviewer for appreciating our work and suggestions provided to improve our manuscript. Changes made to the manuscript are highlighted in red. Below are the answers to the reviewer’s comments.

 

 INTRODUCTION

 

The introduction provides a good context about plyometric training in prepubertal footballers.

Answer: Thanks for the comment.

METHODS

Participants

Provide more information about the demographic data, the experience and the competitive level.

Answer: Thanks for the comment. More information has been provided in “inclusion criteria”

Plyometric Training Program Details

The methodology lacks important information regarding the plyometric training program. Please clarify:

When were the plyometric sessions performed — before or after the main training sessions?

How many times per week were these sessions conducted?

What was the structure in terms of sets, repetitions, and rest intervals?

Including these details is essential for reproducibility and for understanding the potential training load applied to the participants.

Answer: Thanks for the comment. Additional information has been provided in the title of Table 1 of the training program, and a sentence was added in 2.2 Study design.

Statistical Analyses

There appears to be a typographical or conceptual error in the interpretation of Cohen’s d values. You state:

“Effect size (ES) was calculated using Cohen's d and interpreted as small (< 0.20), medium (< 0.50), or large (< 0.80).”

This is inconsistent with standard interpretations. Typically, Cohen’s d is interpreted as:

Small: 0.2

Medium: 0.6

Large: 0.8

Please revise the thresholds and corresponding interpretations to align with conventional standards or provide justification if a different classification is used.

Answer: Thanks for the comment. Change has been done accordingly

 

Suggested Literature for Consideration

You may consider citing the following recent systematic review, which discusses strength training variables and their effects on neuromuscular adaptations in prepubertal children:

Sánchez Pastor, A., García-Sánchez, C., Marquina Nieto, M., & de la Rubia, A. (2023). Influence of Strength Training Variables on Neuromuscular and Morphological Adaptations in Prepubertal Children: A Systematic Review. International Journal of Environmental Research and Public Health, 20(6), 4833. https://doi.org/10.3390/ijerph20064833

Evaluate whether its inclusion would enrich your discussion on the effectiveness and design of training programs in young populations.

Answer: Thanks for the suggestion. The reference [22] has been used for an additional sentence in the discussion section.

 

Reviewer 2 Report

Comments and Suggestions for Authors

General comments:

The study presents an interesting objective and an appropriate design. However, the results mainly show improvements in physical performance in both groups, which is an expected outcome in young athletes undergoing regular training. The only clearly superior gains observed in the plyometric training group were in jump-related tests.

Please ensure consistency in terminology throughout the manuscript. I recommend replacing every occurrence of "football" with "soccer" to reflect standard international scientific usage.

 

Abstract:

L20–21: You did not report the baseline comparisons between groups in the results section (main text). Please include or clarify.

 

Background:

L35–37: The connection of this sentence to your rationale is unclear. Please rephrase or clarify.

L48: The acronym “SSC” (stretch-shortening cycle) is unnecessary as it is only used once. Omit the acronym.

L70–75: Please state the aim first, then the hypothesis. The current order is confusing.

 

Methods:

This section needs improved organization and clarity:

• Study design: Clearly state the type of study (e.g., RCT, quasi-experimental, etc.).
• Participants: The total number of enrolled participants should be clearly indicated here.

L78: If permitted, include the name of the soccer team or academy for context.

 

2.3 Plyometric training program

It is unclear whether the plyometric sessions replaced an existing training session or were added to the current mesocycle. Please clarify.

Table 1: Consider adding visual figures of the exercises (even as supplementary material) to aid replication and understanding.

 

2.4 Physical performance test

When during the season were the pre- and post-tests conducted?

Were both assessments performed on the same day, and at the same time of day? Please specify to ensure reliability.

Clarify the number of trials per test. Did you take the best performance or an average? This must be clearly described.

 

 

2.5 Statistical analysis

L149–150: This sentence is conceptually inverted. Typically, you assess normality first, and based on that, report either the mean ± SD or median (IQR).

L150–152: You did not mention using a paired t-test for the control group as well, please confirm and justify.

Why did you opt for a paired t-test rather than a two-way ANOVA (time × group interaction)? Your current method does not evaluate between-group differences over time.

L154–155: Typographical error: “[18. )”.

L153: Why did you not compare the percentage change (Δ%) between groups (e.g., using an unpaired t-test)? This would provide a more direct between-group comparison.

 

Results:

L157–158: The absence of injuries is an interesting finding. However, injury prevention was not an aim of the study. Please provide a brief rationale before discussing this point further.

 

3.1 Anthropometric parameters

Table 2: This table is not meaningful in its current form. Comparing anthropometric data within groups from T0 to T1 essentially captures natural growth over time (e.g., age, height, mass). Instead, you should include a table comparing baseline and follow-up characteristics between groups, to ensure sample comparability.

 

Discussion:

In general, the discussion lacks clarity and coherence. I suggest restructuring the section to follow the flow of your results more closely.

L190–191: Be consistent with the stated aim in the introduction (i.e., "young elite soccer players before reaching PHV").

L191–193: You discuss a point that was neither introduced in your aim nor reported in the results. Consider integrating it earlier if you wish to include it.

L193–195: This sentence is unclear. Please rephrase for better understanding.

L201–203: The limitation described (regarding comparisons between groups) could have been addressed by using a two-way ANOVA.

L234–237: I agree that your sample size aligns with previous studies on youth soccer players. Please cite relevant references to support this statement.

 

Conclusion:

The conclusion effectively reiterates the main points of the study, but it lacks:

• A clear summary of the key findings
• Emphasis on the practical or theoretical implications
• A deeper reflection on the limitations and specific recommendations for future research

 

L242–243: “Plyometric training significantly enhances lower limb strength in preadolescent soccer players compared to standard training.” This conclusion is not supported by the data. Both groups improved significantly, and between-group differences were only evident (but not tested) in jump tests. You should revise this statement to reflect the partial superiority of PT in specific outcomes.

 

Author Response

Reviewer 2:

General comments:

The study presents an interesting objective and an appropriate design. However, the results mainly show improvements in physical performance in both groups, which is an expected outcome in young athletes undergoing regular training. The only clearly superior gains observed in the plyometric training group were in jump-related tests.

The authors would like to thank the reviewer for appreciating our work and suggestions provided to improve our manuscript. Changes made to the manuscript are highlighted in red. Below are the answers to the reviewer’s comments.

 

Please ensure consistency in terminology throughout the manuscript. I recommend replacing every occurrence of "football" with "soccer" to reflect standard international scientific usage.

Answer: Thanks for the comment. Change has been made accordingly.

Abstract:

L20–21: You did not report the baseline comparisons between groups in the results section (main text). Please include or clarify.

Answer: Thanks for the comment. However, the authors do not fully understand the comment. Lines 20-21 already state the sentence "At baseline, no differences were observed between the two groups in anthropometric or physical performance parameters." Probably we are misinterpreting the reviewer's request.

Background:

L35–37: The connection of this sentence to your rationale is unclear. Please rephrase or clarify.

Answer: Thanks for the comment. The sentence has been rephrased and also the acronym MDP has been removed.

L48: The acronym “SSC” (stretch-shortening cycle) is unnecessary as it is only used once. Omit the acronym.

Answer: Thanks for the comment. Change has been made accordingly.

 

L70–75: Please state the aim first, then the hypothesis. The current order is confusing.

Answer: Thanks for the comment. Change has been made accordingly.

Methods:

This section needs improved organization and clarity:

Study design: Clearly state the type of study (e.g., RCT, quasi-experimental, etc.).

Answer: Thanks for the comment. Change has been made accordingly.

Participants: The total number of enrolled participants should be clearly indicated here.

L78: If permitted, include the name of the soccer team or academy for context.

Answer: Thanks for the comment. Change has been made accordingly.

2.3 Plyometric training program

It is unclear whether the plyometric sessions replaced an existing training session or were added to the current mesocycle. Please clarify.

Answer: Thanks for the comment. An additional sentence has been made to clarify in 2.2 Study design “After warming up, the team split into two groups for 45 minutes and then reunited at the end of the session.”

Table 1: Consider adding visual figures of the exercises (even as supplementary material) to aid replication and understanding.

Answer: Thanks for the comment. The authors understand the purpose of the suggestion. However, they believe that providing images of 16 exercises would significantly burden the reading of the manuscript. Furthermore, since these exercises are widely used in sports, many readers may already know the activity by name.

 2.4 Physical performance test

When during the season were the pre- and post-tests conducted?

Answer: Thanks for the comment. The study was performed during the in-season phase. This has been added at the beginning of the 2.2 Study design.

Were both assessments performed on the same day, and at the same time of day? Please specify to ensure reliability.

Answer: Thanks for the comment. The authors agree with the reviewer. A sentence has been added in 2.4 Physical performance test.

Clarify the number of trials per test. Did you take the best performance or an average? This must be clearly described.

Answer: Thanks for the comment. A sentence has been added at the end of 2.4 Physical performance test.

2.5 Statistical analysis

 

L149–150: This sentence is conceptually inverted. Typically, you assess normality first, and based on that, report either the mean ± SD or median (IQR).

Answer: Thanks for the comment. Change has been made accordingly.

L150–152: You did not mention using a paired t-test for the control group as well, please confirm and justify.

Answer: Thanks for the comment. The reviewer correctly interpreted the text. Thank you for reporting the textual error, which the authors have now replaced with the new statistical analysis section.

Why did you opt for a paired t-test rather than a two-way ANOVA (time × group interaction)? Your current method does not evaluate between-group differences over time.

Answer: Thanks for your insightful comment. We fully agree that a paired t-test alone is not appropriate to assess differences in performance overtime between groups. In response to your suggestion, we have reanalyzed the data using a two-way repeated-measures ANOVA (Time × Group) for each variable. This approach allows us to evaluate both the within-subject effect of time and the interaction between time and group, thus properly addressing between-group differences in change over time.

Significant interaction effects were further explored through Bonferroni-adjusted post hoc comparisons. The revised statistical approach and results are now described in detail in the Methods and Results sections.

 

L154–155: Typographical error: “[18. )”.

Answer: Thanks for the comment. Change has been made accordingly.

L153: Why did you not compare the percentage change (Δ%) between groups (e.g., using an unpaired t-test)? This would provide a more direct between-group comparison.

Answer: Thanks for the comment. Modifications to the statistical analysis with two-way repeated measures ANOVA allowed for between-group assessment. In particular, this information is useful and reported in Table 3.

Results:

L157–158: The absence of injuries is an interesting finding. However, injury prevention was not an aim of the study. Please provide a brief rationale before discussing this point further.

Answer: Thanks for the comment. An additional sentence has been done in 2.3 Plyometric training program

3.1 Anthropometric parameters

Table 2: This table is not meaningful in its current form. Comparing anthropometric data within groups from T0 to T1 essentially captures natural growth over time (e.g., age, height, mass). Instead, you should include a table comparing baseline and follow-up characteristics between groups, to ensure sample comparability.

Answer: Thanks for the comment and suggestions. Table 2 has been reorganized accordingly.

Discussion:

In general, the discussion lacks clarity and coherence. I suggest restructuring the section to follow the flow of your results more closely.

 

L190–191: Be consistent with the stated aim in the introduction (i.e., "young elite soccer players before reaching PHV").

Answer: Thanks for the comment. Change has been made accordingly.

L191–193: You discuss a point that was neither introduced in your aim nor reported in the results. Consider integrating it earlier if you wish to include it.

Answer: Thanks for the comment. In the hypothesis where the safety aspect was added, later in the 2.3 Plyometric training program the choice of load progression to reduce the risk of injury was emphasized. The authors believe that they have thus introduced both the sentences in the results and in the discussion sections.

L193–195: This sentence is unclear. Please rephrase for better understanding.

Answer: Thanks for the comment. Change has been made accordingly.

L201–203: The limitation described (regarding comparisons between groups) could have been addressed by using a two-way ANOVA.

Answer: Thanks for the comment. This part of the manuscript has been modified based on the results of the statistical analysis.

L234–237: I agree that your sample size aligns with previous studies on youth soccer players. Please cite relevant references to support this statement.

Answer: Thanks for the comment. Change has been made accordingly.

Conclusion:

The conclusion effectively reiterates the main points of the study, but it lacks:

A clear summary of the key findings

Emphasis on the practical or theoretical implications

A deeper reflection on the limitations and specific recommendations for future research

Answer: Thanks for the comment. Change has been made accordingly.

L242–243: “Plyometric training significantly enhances lower limb strength in preadolescent soccer players compared to standard training.” This conclusion is not supported by the data. Both groups improved significantly, and between-group differences were only evident (but not tested) in jump tests. You should revise this statement to reflect the partial superiority of PT in specific outcomes.

Answer: Thanks for the comment. Change has been made considering the new statistical analysis.  

Reviewer 3 Report

Comments and Suggestions for Authors

I would like to thank you for the opportunity to review the manuscript entitled "Plyometric Training in Prepubertal Footballers: Is It Really Effective for Soccer Performance?"

The aim of this study was to evaluate the safety and effectiveness of plyometric training in prepubertal footballers.

The article raises an interesting topic, although it requires some additional information and corrections before it is accepted for publication.

Abstract

It is not entirely clear whether the two groups differed only in PLYO training or whether there were also differences in basic training? This requires supplementation.

If both groups had the same baseline training and only the experimental group included plyometric training, could the greater improvement in agility in the CON group indicate that increased lower limb strength reduces agility? Can this be interpreted this way?

The results lack information as to whether this was a statistically significant change.

Study design

Did the PLYO group have the same baseline program as the CON group? Did the groups differ only in PT training? This is not explained well enough, so the study design needs to be improved in the subsection.

Plyometric training program

The PT training program is described too enigmatically. It requires a more detailed description.

Physical performance test

The same applies to physical  tests. Here, too, the test description is insufficient.

Anthropometric parameters

I don't see any intergroup comparisons, only intragroup comparisons before and after the cycle in each group. This needs to be added.

Discussion

Line 209-212. Did the groups have different base programs? This description suggests so, and it may have an impact on the results. ? This is not entirely clear and needs to be explained.

Author Response

Reviewer 3:

I would like to thank you for the opportunity to review the manuscript entitled "Plyometric Training in Prepubertal Footballers: Is It Really Effective for Soccer Performance?"

The aim of this study was to evaluate the safety and effectiveness of plyometric training in prepubertal footballers.

The article raises an interesting topic, although it requires some additional information and corrections before it is accepted for publication.

The authors would like to thank the reviewer for appreciating our work and suggestions provided to improve our manuscript. Changes made to the manuscript are highlighted in red. Below are the answers to the reviewer’s comments.

 

Abstract

 

It is not entirely clear whether the two groups differed only in PLYO training or whether there were also differences in basic training? This requires supplementation.

Answer: Thanks for the comment. Change has been made accordingly.

If both groups had the same baseline training and only the experimental group included plyometric training, could the greater improvement in agility in the CON group indicate that increased lower limb strength reduces agility? Can this be interpreted this way?

Answer: Thanks for the comment. In the abstract it has been specified that the PLYO group's improvements in strength were significant, while the CON group's improvements in agility were non-significant.

The results lack information as to whether this was a statistically significant change.

Answer: Thanks for the comment. Change has been made accordingly as stated in the previous answer.

Study design

Did the PLYO group have the same baseline program as the CON group? Did the groups differ only in PT training? This is not explained well enough, so the study design needs to be improved in the subsection.

Answer: Thanks for the comment. Additional information has been reported in the 2.2 Study design.

Plyometric training program

 

The PT training program is described too enigmatically. It requires a more detailed description.

Answer: Thanks for the comment. The authors are not in agreement with the reviewer and do not understand the reason for the term "enigmatically". The PT program is textual described in 2.3 Plyometric training program and has been specified in Table 1 in terms of typology of exercises, timing (micro and mesocycles), sets and repetitions during the twelve weeks. However, for clarity, the text has been reformulated and the rest between sets has also been included in the legend of Table 1.

Physical performance test

The same applies to physical tests. Here, too, the test description is insufficient.

Answer: Thanks for the comment. Additional information has been provided.

Anthropometric parameters

I don't see any intergroup comparisons, only intragroup comparisons before and after the cycle in each group. This needs to be added.

Answer: Thanks for the comment. The authors agree with the reviewer. Table 2 has been reformatted for between-group comparison, as the intra-group comparison did not provide comparative information, but only confirmation of growth.

Discussion

 

Line 209-212. Did the groups have different base programs? This description suggests so, and it may have an impact on the results. ? This is not entirely clear and needs to be explained.

Answer: Thanks for the comment. The two groups had no differences in base program, as they belonged to the same team that was divided only in the 45 minutes dedicated to the plyometric proposal in the PLYO group. More information has been provided for clarity.

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

Thank the authors for their detailed and thoughtful responses to all comments and suggestions. The manuscript has been substantially improved in terms of clarity, methodological rigor, and consistency.

I am satisfied with the changes made and have no further suggestions. 

I detected a typo at Line 167 "...Bolzano, Italy).[18]."

Author Response

Thank the authors for their detailed and thoughtful responses to all comments and suggestions. The manuscript has been substantially improved in terms of clarity, methodological rigor, and consistency.

I am satisfied with the changes made and have no further suggestions. 

ANSWER: The authors would like to thank the reviewer for appreciating our work and suggestions provided to improve our manuscript. 

 

I detected a typo at Line 167 "...Bolzano, Italy).[18]."

ANSWER: Thank for underlinee the typo. Change has been made accordingly. 

 

Reviewer 3 Report

Comments and Suggestions for Authors

Thank you for the opportunity to review this manuscript again. After reviewing the second version and the authors' responses to the review, I believe that the manuscript is suitable for publication in a journal in this form.

Author Response

Thank you for the opportunity to review this manuscript again. After reviewing the second version and the authors' responses to the review, I believe that the manuscript is suitable for publication in a journal in this form.

ANSWER: The authors would like to thank the reviewer for appreciating our work and suggestions provided to improve our manuscript.