A Novel Method for Field Measurement of Ankle Joint Stiffness in Hopping

Round 1

Reviewer 1 Report

Thank you for submitting your paper. The work done here draws attention to a significant subject in ankle joint stiffness. I have found the paper to be interesting. However, several issues need to be addressed properly before the paper is being considered for publication. My comments including major and minor concerns are given below:

1. Please consider reviewing the abstract and highlight the novelty, major findings, and conclusions. I suggest reorganizing the abstract, highlighting the novelties introduced. The abstract should contain answers to the following questions:
2. What problem was studied and why is it important?
3. What methods were used?
4. What conclusions can be drawn from the results? (Please provide specific results and not generic ones).
5. The abstract can be improved. Please use numbers or % terms to clearly shows us the results in your experimental work. Please expand the abstract.
6. Please consider reporting on studies related to your work from mdpi journals.
7. In the introduction especially at the end, there are too many small paragraphs. Please combine all small paragraphs into larger ones.
8. Please add a list of nomenclature before references for all abbreviations, Greek letters, symbols and letters used in the study.
9. Please avoid using we, our or us in the article
10. What are the limitations in the new method in comparison to other similar models in the open literature, please mention that in section 2.2
11. Figure 1 theta 2 angle is not clear, please move it slightly away so we can see it in the figure and better indicate where it is.
12. Please use consistent format for figures.
13. The figures are poorly presenting the data, please improve their quality to a journal standard level.
14. Line 264 the authors need to discuss the details of each of these past studies in detail and compare against their study, highlight more similarities and differences between your work and past studies in the open literature.
15. Line 265 different format of referencing is used, the authors need to check the guide for authors for the journal and use appropriate and same referencing format in the whole article.
16. Line 278 does not read well, it is not clear and does not provide a meaningful information that can be clearly understood.
17. Some of the results are merely described and is limited to comparing the experimental observation and describing results. The authors are encouraged to include a more detailed results and discussion section and critically discuss the observations from this investigation with existing literature.
18. Conclusion can be expanded or perhaps consider using bullet points (1-2 bullet points) from each of the subsections.

Author Response

Thank you for your insightful comments and constructive suggestions on our paper.

Please see the attachment

Author Response File: Author Response.pdf

Reviewer 2 Report

The author aimed to develop a simple method for calculating the ankle joint stiffness (AJS), without a need for motion analyses and measurements of ground reaction force. 

The paper is very well written and I am sure it is going to have success. 

Author Response

We appreciate the time and effort that you have dedicated to providing your feedback on our manuscript.

Thank you so much.

Reviewer 3 Report

The following is the summary of the present manuscript:

    This study presents a novel method for measuring AJS during hopping task with no force or motion measurement system. Twelve participants performed the con-trolled hopping task at2.2 Hz, on a force platform, and six high speed cameras recorded the movement. The contact time and flight time were used to calculate ground re-action force, and an inverse kinematic and inverse dynamic approaches were used to calculate the ankle kinematic and kinetic. The AJS of twelve subjects measured by new method and com-pared to the results of reference method. The calculated AJS using this method showed a significant correlation (r=0.752) against the measured AJS using conventional method. The validation test displayed an average mean difference for translation of -24.76%. The presented method can be used as a tool for assessing AJS in the field.

This is an interesting article. I have several comments:

First, in line 43, please specify which review paper the authors refer to.

Second, in line 51, there is no need to add an “a” before reliability.

Third, in line 77, a reference is needed after “Dalleau”.

Fourth, please add a figure to show how the reflective figures are attached to human bodies.

Fifth, in figure 4, please add a footnote to explain what teta is.

Author Response

Thank you for your insightful comments and constructive suggestions on our paper.

Please see the attachment

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Dear Authors, at the end of the manuscript, you need to indicate information/statement about obtaining permission to publish data related to human, and using their pohotos. Please check the guide for authors in the journal site. 

Author Response

The following sentence is now added  at the end of the manuscript as "Institutional Review Board Statement":

The study was conducted according to the guidelines of the Declaration of Helsinki, and approved by the Research Ethics Committee of the University of Tehran (Approval ID: IR.UT.SPORT.REC.1397.019, 7 October 2018)