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  • Giuseppe Di Lascio 1,2,
  • Giuseppe Giardullo 1,2 and
  • Gaetano Raiola 2,3
  • et al.

Reviewer 1: Anonymous Reviewer 2: Jacielle Carolina Ferreira Reviewer 3: Yihan Huang

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors
  1. Despite the extensive literature on SSC and its implications in sports, to date there are no studies that have specifically investigated the relationship between ankle joint mobility and the efficiency of the lengthening-shortening cycle, particularly in relation to the Achilles tendon and the motor gesture of vertical jump. Considering the study: Zhang Q, Li F, Trowell DA, et al. Optimizing stretch-shortening cycle performance: effects of drop height and landing strategy on lower-limb biomechanics in drop jumps. PeerJ. 2025;13:e19490. Published 2025 May 21. doi:10.7717/peerj.19490, please rephrase the novelty section.
  2. Please specify the inclusion and exclusion criteria more clearly.
  3. It is recommended to include a normality test (Kolmogorov-Smirnov, Shapiro-Wilk or Anderson-Darling).
  4. Please include the sample size calculation, statistical power, or both.
  5. The recommendation is to specify that the study has complied with the Declaration of Helsinki (DoH)—Ethical Principles for Medical Research Involving Human Participants (1964) and its latest amendments adopted by the 75th General Assembly of the World Medical Association (WMA) in Finland on 19 October 2024.
  6. It is mandatory to specify which statistical software was used to perform the statistical analysis.
  7. Discussions should begin by specifying the purpose of the paper and clearly indicating whether it has been accomplished.
  8. Please place greater emphasis on comparing your results with those of other similar studies.
  9. The conclusions should be systematized in relation to the paper's title and the results obtained.
  10. Given the journal's prestige, please remove or replace the following outdated bibliographical sources from the study: 4-12, 18, 22, 24-25, 27, 29.
Comments on the Quality of English Language

Major revisions to the English language are required.

Author Response

We sincerely thank the reviewer for the constructive and insightful comments. Below are our detailed point-by-point responses. We trust that these revisions address the concerns raised and enhance the clarity and scientific rigor of the manuscript.

  1. Comment: Considering the study: Zhang Q, Li F, Trowell DA, et al. Optimizing stretch-shortening cycle performance: effects of drop height and landing strategy on lower-limb biomechanics in drop jumps. PeerJ. 2025;13:e19490. Published 2025 May 21. doi:10.7717/peerj.19490, please rephrase the novelty section.
    Response: The novelty section has been revised to incorporate the findings from Zhang et al. (2025) and to clarify that, despite advances in SSC-related research, no previous studies have specifically examined the relationship between ankle joint mobility and SSC efficiency in the context of vertical jump performance and Achilles tendon dynamics.

 

  1. Comment: Please specify the inclusion and exclusion criteria more clearly.
    Response: We have revised the Methods section to provide a clearer definition of both inclusion and exclusion criteria. Specifically, the inclusion criteria now state that participants were aged between 18 and 30 years, healthy, recreationally active, and had no history of lower-limb injuries within the past six months. The exclusion criteria now include any history of Achilles tendon pathology, current musculoskeletal disorders, or medical conditions that could impair physical performance or pose a health risk during testing.

 

  1. Comment: It is recommended to include a normality test (Kolmogorov-Smirnov, Shapiro-Wilk or Anderson-Darling).
    Response: As recommended, we have added the Shapiro-Wilk test to assess the normality of the data distribution.

 

  1. Comment: Please include the sample size calculation, statistical power, or both.
    Response: A priori sample size calculation was conducted using G*Power software (version 3.1), targeting a power of 0.80, α = 0.05, and a moderate effect size (f = 0.25). This analysis supported the final sample size used.

 

  1. Comment: Specify compliance with the Declaration of Helsinki.
    Response: We have now explicitly stated that the study adhered to the Declaration of Helsinki and its latest amendments adopted by the 75th WMA General Assembly (Finland, 19 October 2024).

 

  1. Comment: Specify which statistical software was used.
    Response: We have included that all statistical analyses were conducted using SPSS Statistics (version 25.0, IBM, SPSS Inc., Armonk, NY, USA).

 

  1. Comment: Discussions should begin by specifying the purpose and whether it was achieved.
    Response: The opening paragraph of the Discussion has been revised to clearly state the study’s aim and confirm that the objectives were successfully met.

 

  1. Comment: Place greater emphasis on comparing results with similar studies.
    Response: We have expanded the Discussion to include a more thorough comparison of our results with relevant studies, including recent work by Zhang et al. (2025), as well as others addressing ankle mobility and SSC performance.

 

  1. Comment: Systematize conclusions based on the title and results.
    Response: The Conclusion section has been restructured to directly reflect the study’s title and the key findings, emphasizing the observed link between ankle mobility and SSC efficiency.

 

  1. Comment: Remove or replace outdated sources (refs 4–12, 18, 22, 24–25, 27, 29).
    Response: The specified references have been critically reviewed and replaced with more recent and relevant literature where appropriate.

Reviewer 2 Report

Comments and Suggestions for Authors

The introduction could provide more information on the relationship between tendon stiffness and elastic capacity. The objective and title need to be changed without referring to the chyle tendon. The methodology is in dire need of improvement. A critical point is the control of squat depth during the eccentric phase of jumps. Unfortunately, if this control is not strictly maintained, the data may be discarded, as a different excursion between jumps by the same subject would directly impact stiffness, stored potential energy, and possibly performance, thus being a significant confounding factor. The results and discussion need to be described with greater caution, as non-significant correlation and regression results should not be mistaken for trends.

INTRODUCTION:

 

Line 54: It's a statement, without prior reference, that directly links the degree of dorsiflexion to the effectiveness of the SSC. Since there is no evidence of this relationship in the literature, the statement needs to be rephrased as "a possibility."

Line 63: The SSC involves different mechanisms, and even though the division between groups occurred based on the degree of ankle joint mobility, any potential differences between groups cannot be attributed to Achilles tendon efficiency. Therefore, I strongly recommend rewriting this objective.

 

METODOLOGY:

Line 72-73: standard deviation?

Line: 75-76: Per week?

On which days was each test performed?

Was there prior familiarization? Especially with the jump tests.

How many jump attempts were performed? Which was adopted for statistical analysis?

What was the position of the upper limbs during the jumps?

How was it possible to ensure that the subjects squatted to 90 degrees in both jumps before performing the concentric phase?

How long did the subjects squat during the squat jump before the concentric phase?

What was the width between the feet adopted?

Was the force platform used uniaxial or triaxial? What was the sampling rate? And how was jump height quantified?

How long after the warm-up were the tests performed and in what sequence?

How were the groups divided?

 

RESULTS:

Line 120: What was the result of the correlation?

Figure 1 and Table 5 do not have units of measurement.

Standardize the term to name the difference between CMJ and SJ.

If, for example, one subject jumps 42 and 40 cm, and another subject jumps 22 and 20 cm in CMJ and SJ, respectively, both would have the same 2 cm difference. However, for the first subject, this difference represents a 5% increase in jump height, and for the other, a 10% increase. Is the use of the absolute difference more appropriate than the percentage difference between the jumps?

 

DISCUSSION:

Line 143: The term "width" is not the most appropriate.

Lines 163–164: In the absence of a significant result, I recommend removing this information, as it may lead to the understanding that there is a tendency for SSC to decrease with increasing ankle mobility.

Line 186: "Although the high-mobility group showed higher average values." If there was no significant difference, I would avoid this statement.

Line 195: Remaining dot

Line 202: Missing dot

 

CONCLUSION:

Lines 218–221: I strongly recommend removing the statement because the correlation and regression results were not significant.

Lines 224–233: I strongly recommend removing it because it should address the conclusion of this study. The statements about training were not tested, and the limitations of the study have already been addressed.

 

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors
  1. Line 55 and Line 66: Abbreviations should be defined at their first occurrence in the manuscript. Please review and revise the manuscript accordingly to ensure consistency throughout
  2. Line 80: Did you measure the participants’ body temperature? For example, did the power exercise begin only after all participants reached the same baseline temperature, or after their body temperatures increased by the same amount?
  3. Table 1 & 2:
    1. The training content can be summarized in the Methods section, with detailed information and a schematic provided in the Appendix.
    2. How long did the warm-up last, and was there a defined endpoint or criterion for concluding the warm-up?
    3. Was the box jump height consistent across all participants? Also, for '3×5', does this refer to sets × repetitions, or repetitions × sets? Was there any rest provided between sets or between different movements? If so, please specify the duration.
  4. Line 111-113:
    1. What criteria were used to divide participants into high and low mobility groups? This should be clearly described in the earlier sections, including the number of participants in each group and relevant characteristics such as sex, weight, height, and age. Additionally, male and female participants should be analyzed separately rather than grouped together.
    2. Was the significance level set at 0.05, or was a different threshold used? Please specify.
  5. Table 3: 
    1. From my understanding, there may be differences between male and female participants. I suggest separating the results by sex to allow for clearer interpretation.
    2. The results for ankle mobility should be reported with consistent decimal places throughout the manuscript.
    3. There was one negative elastic contribution observed (-1.13); an explanation should be provided in the following section.
  6. Figure 1: Please add titles and units to the X and Y axes, as well as include the linear regression equation on the figure.
  7. Table 4: Please explain the meaning of all variables and describe how each is calculated in the Methods section.
  8. Since the joint width of the ankle was not measured, how did you relate your results to the ankle joint width?
  9. Line 177-179: These points should be addressed earlier in the manuscript. Additionally, you should explain the rationale for separating participants into high and low mobility groups.
  10. Line 195-211:
    1. The limitations section should be summarized and possibly shortened for conciseness.
    2. (Line 195) There is an unnecessary dot at the beginning; please remove it.
Comments on the Quality of English Language
  1. Please check the verb tense throughout the manuscript to ensure consistency.
  2. Please verify that each abbreviation is defined at its first occurrence and used consistently throughout the manuscript.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Congratulations on your hard work in developing this scientific material.

Author Response

Comment: Congratulations on your hard work in developing this scientific material.

Response: Thank you for your kind words and positive feedback. We truly appreciate your recognition of the effort that went into developing this scientific work. 

Reviewer 2 Report

Comments and Suggestions for Authors

Standardize the axes in Figure 1.


Inform which of the ground reaction forces was used to calculate the jump height (e.g., takeoff speed, landing time).

Author Response

Comment 1: Standardize the axes in Figure 1.

Response: We appreciate your insightful comment. Accordingly, we have standardized the axes in Figure 1 by setting an appropriate range for the X-axis and formatting the labels to eliminate unnecessary decimal points. These adjustments improve both clarity and consistency across the figure.

Comment 2: Inform which of the ground reaction forces was used to calculate the jump height (e.g., takeoff speed, landing time).

Response: Thank you for your observation. In response, we have clarified in the manuscript that jump height was calculated using vertical ground reaction force (vGRF) data. Specifically, take-off and landing instants were identified based on the disappearance and reappearance of vertical force, allowing the calculation of flight time and, consequently, jump height.

 

Reviewer 3 Report

Comments and Suggestions for Authors

Table 1: Under Warm up, at the end of “standing: ..., linear skip alt,” the comma is extraneous or should be replaced with a period?

Otherwise, the authors have addressed my comments clearly. Thank you.

Author Response

Comment: Table 1: Under Warm up, at the end of “standing: ..., linear skip alt,” the comma is extraneous or should be replaced with a period?

Response: This was a typographical oversight. The comma at the end of ‘standing: ..., linear skip alt,’ has been removed.