Video-Biomechanical Analysis of the Shoulder Kinematics of Impact from Sode-Tsurikomi-Goshi and Tsurikomi-Goshi Judo Throws in Elite Adult Judoka

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Dear authors,

This research study has much value. This study offers valuable insights into the biomechanics of judo throws, demonstrating a statistically significant difference in peak negative velocity during Tsurikomi-Goshi compared to Sode-Tsurikomi-Goshi, suggesting that uke (Note: this needs to be made clearer earlier in the paper of what it is) is thrown quicker in the former. While the results highlight meaningful trends. 

My specific feedback for each section of the paper is in the attached PDF. I have provided questions, suggestions and also strike-throughs. For the Methodology, it is important that you demonstrate that the Huawai 5T with a 48-megapixel camera, used to record the throws, is a valid and reliable tool for capturing videos to be used for measurement. 

Please attend to the comments and concerns raised in the PDF version of your manuscript. 

Kindest regards

Comments for author File: Comments.pdf

Comments on the Quality of English Language

There are some minor issues with the grammar and formation of paragraphs. In the manuscript attached for the authors, my feedback has included changes to improve the quality of the English.

Author Response

Dear Reviewer,

We sincerely thank you for your thorough review and valuable comments on our manuscript. Your feedback has been instrumental in improving the quality and clarity of our work. Below, we provide detailed responses to your comments and outline the revisions made in the manuscript.

1. Comments on the Abstract

Reviewer Comment: Missing space before "Huawei" and formatting issues, such as lack of spaces after periods.

Response: Thank you for pointing out these issues. All formatting errors in the abstract have been corrected. A missing space before "Huawei" has been added, and spaces after periods have been properly adjusted throughout the abstract.

2. Comments on the Introduction

Reviewer Comment: Please provide an example for the term "judokas" and include references supporting the data on injury risk.

Response: As suggested, we have added an example to clarify the term "judokas" (e.g., fighters or opponents) to enhance understanding for a broader audience. Additionally, references have been included to support the data on injury risk, particularly with regard to shoulder injuries in judo.

3. Comments on Figures and Tables

Reviewer Comment: Figures should be placed directly below the corresponding text. Tables require column headings.

Response: Figures have been repositioned to appear directly below the relevant paragraphs where they are discussed. Column headings have been added to the tables to improve readability and align with the reviewer's requirements.

4. Comments on the "Materials and Methods" Section

Reviewer Comment: Subheadings are missing, and the description of the camera and its limitations needs to be detailed.

Response: Subheadings such as "Recruitment and Participants," "Procedures," and "Statistical Analysis" have been introduced to improve the structure of the "Materials and Methods" section. Additional details regarding the use of the 30 Hz camera have been added, including the rationale for its selection and its limitations compared to higher-frequency equipment.

5. Comments on the Discussion

Reviewer Comment: Key terms like "impact" and "negative velocity" need to be defined, and results should be contextualized with previous studies.

Response: Key terms have been defined in appropriate sections to improve clarity. For example, "negative velocity" is described as "the peak speed of uke’s shoulder at the moment of contact with the mat, moving in the opposite direction of the initial motion." The discussion has been expanded to include references to previous studies that support the importance of the findings in the context of judo biomechanics.

6. Comments on the Conclusions

Reviewer Comment: Practical applications of the findings are missing.

Response: The conclusions section has been expanded to highlight practical applications, such as recommendations for coaches to optimize throwing techniques and implement injury prevention strategies, including improved breakfall (ukemi) training.

Reviewer 2 Report

Comments and Suggestions for Authors

We would like to express our gratitude to the authors for their research in the field of judoka and for contributing to the advancement of this discipline. We find the study to be meaningful and support its publication after revisions. Below are our comments and suggestions:

1. Formatting:
   The formatting should be strictly revised, such as appropriately completing affiliations (Affiliation 1-5) according to the journal's requirements.

2. Delay in Publication:
   Why was this study, conducted in December 2020, only submitted for publication now? Was there an issue related to ethical review or compliance?

3. Participant Recruitment:
   The age range of participants (18–42 years) is quite broad. How was the reliability and validity of the experimental results ensured given this large age disparity? Were statistical requirements met to validate the results across such a diverse group? Additionally, what specific judo styles or techniques do the participants practice? Were their technical approaches largely similar? Given that all participants came from the same dojo (The Aris Judo Club), could this homogeneity in training styles limit the generalizability of the results?

4. Kinematic Data Collection:

   • Can the Huawei 5T smartphone provide sufficient precision for kinematic data collection?
   • Why was two-dimensional motion analysis chosen instead of three-dimensional analysis, and how might this choice affect the accuracy of the results?
   • Has the calibration and analytical process of Kinovea software been validated? Were factors such as camera angle and measurement error accounted for during analysis?
   • Are there published references supporting the validity of the methods used in this study?

5. Table 1:

   • Table 1 lacks a title.
   • Was the A-B experiment conducted only once? If so, how was reproducibility ensured without repeated measurements?

6. Data Acquisition:

   • How were the data for TG and STG obtained? Were they directly measured using instruments, or calculated based on derived data?

7. Statistical Methods:

   • Were the statistical methods (e.g., p-value and effect size calculations) sufficiently robust? Would additional statistical tests or alternative analyses strengthen the conclusions?
   • Why does Table 1 not include p-values?

8. Test-Retest Reliability:
   Why was the test-retest reliability of STG (ICC=0.74) higher than that of TG (ICC=0.60)? Could this be due to differences in technical complexity or participants' familiarity with the techniques?

9. Further Research on Impact Forces:
   The conclusion mentions the need for further research on "impact forces." Are there any indirect data from this study to support this recommendation?

10. Environmental Variables:
    Did the study control for environmental factors such as lighting conditions, floor friction, or other variables during the execution of the throws?

11. Gender Comparison:
    Has the inclusion of elite female judo players been considered to investigate potential gender differences in shoulder kinematic characteristics?

12. Practical Applications:
    How can the findings of this study provide practical guidance for judo training? What implications do the results have for improving throwing efficiency or reducing injury risk?

13. Integration with Biomechanical Data:
    Are there any plans to integrate this type of kinematic analysis with biomechanical data, such as muscle activity or ground reaction forces, to gain a more comprehensive understanding of the characteristics of judo throws?

Author Response

Dear Reviewer,

We sincerely thank you for your positive evaluation of our study and for the detailed and constructive comments, which have significantly helped improve the manuscript. Below, we provide responses to each of your comments and outline the changes made in the manuscript.

Formatting

Reviewer Comment: The formatting should be carefully reviewed, including appropriately completing affiliations (Affiliation 1–5) according to the journal's requirements.

Response: Affiliations have been corrected and updated according to the journal's requirements. Additionally, the entire manuscript has been reformatted to ensure full compliance with editorial guidelines.

Delay in Publication

Reviewer Comment: Why was this study, conducted in December 2020, only submitted for publication now? Was there an issue related to ethical review or compliance?

Response: The delay in publication was due to the time-consuming process of data analysis and incorporating internal feedback from our team. The ethical review process was completed in 2020 without any issues, and the approval number is provided in the manuscript.

Participant Recruitment

Reviewer Comment: The age range of participants (18–42 years) is quite broad. How was the reliability and validity of the results ensured given this disparity? Were techniques uniform? Could the homogeneity of training styles in one dojo limit the generalizability of the results?

Response: Reliability was ensured through statistical tests that accounted for variability due to age. All participants were elite judokas with similar competitive experience and technical skill levels. The techniques used were uniform, minimizing potential errors from stylistic differences. We acknowledge that recruiting from a single dojo may limit generalizability, and this has been discussed in the "Limitations" section.

Kinematic Data Collection

Reviewer Comment: Can the Huawei 5T smartphone provide sufficient precision for kinematic data? Why was two-dimensional motion analysis chosen instead of three-dimensional analysis? Was the calibration and analytical process of Kinovea software validated?

Response: The Huawei 5T was chosen for its availability and validated use in prior studies for 2D biomechanical analyses. Two-dimensional analysis was used due to equipment limitations and the study's objectives; however, we plan to utilize 3D analysis in future research for greater precision. The calibration and analysis processes in Kinovea were based on previously published studies confirming its reliability.

Table 1

Reviewer Comment: Table 1 lacks a title. How was reproducibility ensured when experiments (e.g., A-B) were conducted only once?

Response: A title has been added to Table 1 for better clarity. Reproducibility was ensured through test-retest reliability assessments for all throws, and additional throws were performed in cases of technical inconsistencies.

Statistical Methods

Reviewer Comment: Were the statistical methods sufficiently robust? Why does Table 1 not include p-values?

Response: Statistical methods, such as paired t-tests and ICC analysis, were conducted in line with best practices. Effect sizes (Cohen’s d) were also calculated for additional rigor. P-values are provided in the text of the results section, which has been clarified in the manuscript.

Test-Retest Reliability

Reviewer Comment: Why was the test-retest reliability of STG (ICC=0.74) higher than TG (ICC=0.60)? Could this be due to differences in technical complexity?

Response: The difference in ICC values may result from the greater technical complexity of TG, which made it harder to execute consistently. This has been noted in the discussion as a potential factor influencing the results.

Further Research on Impact Forces

Reviewer Comment: Are there any indirect data from this study to support the recommendation for further research on impact forces?

Response: Indirect data from our study, such as differences in negative velocity, suggest potential differences in impact forces. This has been highlighted in the conclusions as justification for further research.

Environmental Variables

Reviewer Comment: Did the study control for factors such as lighting, floor friction, etc.?

Response: Environmental factors, such as lighting conditions and floor surface, were standardized according to International Judo Federation (IJF) recommendations.

Gender Comparison

Reviewer Comment: Has the inclusion of elite female judo players been considered?

Response: This study was limited to male participants due to the availability of subjects. We plan to include female participants in future research to explore potential gender differences in throw kinematics.

Practical Applications

Reviewer Comment: How can the findings of this study provide practical guidance for judo training?

Response: The findings suggest that coaches should place greater emphasis on optimizing biomechanical techniques and implementing injury prevention strategies, such as training in breakfall (ukemi) techniques. These practical implications have been expanded in the conclusions.

Integration with Biomechanical Data

Reviewer Comment: Are there plans to integrate kinematic analysis with biomechanical data?

Response: Future studies will expand the analysis to include biomechanical data, such as muscle activity and ground reaction forces, to provide a more comprehensive understanding of the mechanics of judo throws.

Reviewer 3 Report

Comments and Suggestions for Authors

Major Recommendations

Include a larger, more diverse participant pool, including female judokas and athletes of varying skill levels.

Employ three-dimensional motion analysis or use markers to enhance accuracy in kinematic tracking.

Investigate impact force calculations directly to validate inferences from velocity and acceleration data about injury risks.

 

 

Minor Recommendations

Define key terms such as "impact" and "negative velocity" more explicitly in the context of judo throws.

Use annotated images or diagrams to illustrate the kinematic differences between STG and TG techniques clearly.

Author Response

Response to Major Recommendations

Recommendation: Include a larger, more diverse participant pool, including female judokas and athletes of varying skill levels.
Response: Thank you for this recommendation. The current study focused on a homogeneous group of elite male judokas to minimize variability in the results. However, we recognize the importance of diversity. In future research, we plan to include female judokas and athletes with varying skill levels to explore potential kinematic differences and improve the generalizability of the findings.

Recommendation: Employ three-dimensional motion analysis or use markers to enhance accuracy in kinematic tracking.
Response: We acknowledge the limitations of two-dimensional motion analysis and the absence of markers. The current setup was constrained by available resources. In future studies, we plan to employ three-dimensional motion analysis and marker-based tracking systems to enhance the precision and reliability of kinematic data.

Recommendation: Investigate impact force calculations directly to validate inferences from velocity and acceleration data about injury risks.
Response: We agree that direct measurements of impact forces could significantly enrich the findings. In future research, we aim to expand the analysis to include such measurements, which will provide a more accurate assessment of injury mechanisms and validate the conclusions drawn from this study.

Response to Minor Recommendations

Recommendation: Define key terms such as "impact" and "negative velocity" more explicitly in the context of judo throws.
Response: We have expanded the definitions of key terms in the relevant sections of the text. For example, "impact" is now defined as the moment of first contact between uke’s shoulder and the mat, and "negative velocity" is described as the peak speed of uke’s shoulder moving in the opposite direction of the initial motion. These changes aim to make the terms clearer for readers.

Recommendation: Use annotated images or diagrams to illustrate the kinematic differences between STG and TG techniques clearly.
Response: Updated diagrams and annotated images have been included to visually represent the kinematic differences between STG and TG techniques. This should make it easier for readers to understand the distinctions between these techniques.

Reviewer 4 Report

Comments and Suggestions for Authors

1. Although the importance of judo throwing technology in competition is mentioned, there is a lack of detailed review of the current research status, especially the research on the biomechanics of shoulder motion, especially the research on the changes of shoulder force, acceleration, and speed in judo throwing technology, to highlight the innovation and importance of this research.

2. To help readers better understand the importance and practical significance of this study, it is suggested to add a detailed description of shoulder injuries in judo. Please list common types of shoulder injuries (rotator cuff injury, acromioclavicular dislocation, etc.) and explain the mechanisms and contributing factors of these types of injuries.

3. In addition to the injury risk data of judo athletes during the Olympic Games mentioned in the article, what other data indicates that the risk of shoulder injury is higher in Judo?

4. When selecting the sample, does recruiting athletes from only one Judo Club affect the representativeness of the sample? How can I ensure that my sample is representative of all elite adult judo athletes?

5. The equipment used, data collection frequency, data processing and analysis methods are not detailed in the data collection part. It is recommended to describe the data collection equipment used and its performance parameters in detail and explain the rationality of the data collection frequency (such as 30Hz), as well as the data processing and analysis method. At the same time, this research uses Huawai 5T mobile phone to shoot. Although certain shooting conditions are set, what errors may exist compared with professional high-speed cameras? How is the impact of these errors on the results assessed? At the same time, when performing 2D motion analysis, what is the possible margin of error for manually tracking reference points because you cannot add markers to the participants? How to reduce this error?

6. It is found in the study that although the value of acromial acceleration in TG technology is high, the difference is not statistically significant, while the difference of negative velocity is statistically significant. How to explain the significance of the inconsistency between the results of acceleration and negative velocity in actual judo? At the same time, when comparing STG in standing and kneeling positions, although the difference in various indicators was not statistically significant, there were some differences in numerical terms. Is it possible that these differences could become significant in a larger sample size or among athletes of different levels?

7. Although the existing studies are mentioned, the comparison is not sufficient. It is suggested to explain the causes and mechanisms of the research results by combining the actual situation of judo and biomechanical principles. Even some advanced musculoskeletal modeling to reveal injury mechanisms: New insights optimize landing strategies to reduce lower limb injury risk (https://doi.org/10.34133/cbsystems.0126). Furthermore, when explaining the research results of uneven shoulder stress of judo athletes during throwing, it can be combined with the actual situation of judo to point out the stress characteristics and differences of shoulders in different throwing techniques. The causes and mechanisms of uneven shoulder force, such as the contraction pattern of shoulder muscles, rotation Angle and speed of joint, are analyzed. This combination helps the reader to gain a deeper understanding of the causes and mechanisms of the findings.

8. According to the research conclusions, what adjustments can be made to the actual judo competition rules or training system to better protect athletes from shoulder injuries? At the same time, the authors emphasize the role of ukemi techniques and MATS, so how should these factors be emphasized to prevent shoulder injuries at different levels of judo training (e.g., beginner, intermediate, advanced)?

9. Although the potential significance of the findings for the training of judo athletes and the prevention of shoulder injuries is mentioned, the practical application value is not fully elaborate. Please elaborate on the practical application value of the research results in the training of judo athletes and the prevention of shoulder injury, put forward specific suggestions or guiding principles, and discuss its possible promotion and application prospects.

Author Response

1. Lack of a detailed review of the current research status on the biomechanics of shoulder motion in judo.

Response: Thank you for this comment. We have expanded the introduction section to include a more detailed review of current research on the biomechanics of shoulder motion in judo. We have added a discussion of changes in force, acceleration, and speed during judo throwing techniques, which highlights the innovation and significance of our study.

2. Add a detailed description of shoulder injuries in judo.

Response: We have included a detailed description of common shoulder injuries in judo, such as rotator cuff injuries and acromioclavicular dislocations, along with explanations of their mechanisms and contributing factors. This information aims to help readers better understand the importance and practical implications of our study.

3. Additional data indicating a higher risk of shoulder injuries in judo.

Response: We have added additional data from the literature that indicates an increased risk of shoulder injuries in judo beyond the Olympic Games data. This includes studies on national competitions, training sessions, and epidemiological data from various levels of athlete expertise.

4. Representativeness of the sample recruited from a single judo club.

Response: We acknowledge that recruiting participants from a single club may limit the representativeness of the sample. This limitation has been discussed in the "Limitations" section. In future research, we plan to enhance the diversity of the sample by including athletes from multiple clubs and regions.

5. Details on equipment, data collection frequency, and analysis methods.

Response: The data collection section has been expanded with detailed information about the equipment used (Huawei 5T), its performance parameters, and the rationale for selecting a 30 Hz frequency. We have discussed potential errors associated with using a smartphone compared to professional high-speed cameras, the margin of error in manually tracking reference points without markers, and the methods implemented to minimize these errors.

6. Differences in acceleration and negative velocity results and the potential impact of a larger sample size.

Response: The discrepancies between acceleration and negative velocity results have been addressed in the discussion section, where we explained their significance in the context of judo biomechanics. We also noted that a larger sample size or analysis involving athletes of varying skill levels could reveal statistically significant differences that are currently only observed numerically.

7. Linking results with biomechanics and advanced musculoskeletal models.

Response: We have expanded the discussion to analyze the mechanisms of uneven shoulder forces in different judo throwing techniques. The causes of these differences, such as shoulder muscle contraction patterns, joint rotation angles, and speeds, have been explained. We also discussed the potential use of advanced musculoskeletal modeling in future studies to further elucidate injury mechanisms.

8. Adjusting competition rules and training systems to protect athletes.

Response: We have proposed potential changes to judo competition rules and training systems, such as emphasizing breakfall (ukemi) techniques and using mats with improved shock-absorbing properties. Different approaches to ukemi training for beginner, intermediate, and advanced athletes have also been suggested.

9. Expanding the practical application of the findings.

Response: The conclusions section has been expanded to elaborate on the practical applications of the findings in judo training and shoulder injury prevention. We have provided specific recommendations and guidelines that can be implemented in training programs and discussed the potential for promoting and applying the study's findings more broadly.

Reviewer 5 Report

Comments and Suggestions for Authors

Dear Authors,

After a detailed analysis of your manuscript entitled "Video-biomechanical analysis of the shoulder kinematics of impact from Sode Tsurikomi Goshi and Tsurikomi Goshi judo throws in elite adult judoka", I present comments and suggestions for improving the work. From the point of view of this reviewer, the manuscript in its present state is not suitable for publication. I recommend that it be revised and, if possible, that the research be supplemented or even reformulated.

Please consider the questions and notes as guidelines for reviewing and improving the manuscript:
1. Textual Problems
1.1. In line 40, the excerpt "[2men9]" appears to be a typo or a poorly formatted reference. Could you check and correct this?
1.2. Between lines 78 and 85, the numbers identifying the questions do not have enough space between them. Please check this to ensure clarity.
1.3. Several sections have inconsistent spacing and formatting issues, such as figures 2 and 3. Please standardize the spacing and adjust the presentation of the figures.
1.4. Figure 4 requires a higher resolution. Can you provide a lower-resolution version?
1.5. The tables have inconsistencies with the model presented by MDPI, such as the absence of a title line in some of them and the excess of lines in Table 1. I recommend that the formatting of the tables be adapted to the standard required by the publisher.

2. Methodology and Equipment
2.1. The computer programs (Kinovea and SPSS) and equipment used do not have any information proving compliance with the standards of the International Committee of Medical Journal Editors (ICMJE). Could you provide details on the validation and certification of the equipment?
2.2. Recording at 30 Hz is insufficient for the precision required for kinematic analysis. Have you considered using equipment with a higher acquisition frequency? If this is not feasible, how do you intend to address this limitation in detail in the text?
2.3. The definition of "impact" is unclear. Can you standardize and better specify what is considered an impact in the context of the study?

3. Sampling and Generalizability Issues
3.1. Only six participants were included in the study. How do you justify the statistical robustness of this sample size? Would it be possible to include more participants or should this be acknowledged as a limitation that affects the validity of the results?
3.2. The lack of female participants limits the applicability of the results. Are there plans to include a more diverse sample in future studies? How does this exclusion affect the generalizability of the findings?
3.3. The lack of rigorous control of weight categories compromises pairwise comparisons. Can you elaborate on how this was addressed or include this point in the limitations?

4. Statistical Analysis
4.1. Although the use of paired t-test is a widely accepted statistical method for comparing continuous variables in dependent groups, its use in this study is limited by the small sample size. With small sample sizes, the t-test may not have sufficient statistical power to detect significant differences, increasing the risk of Type II error.
4.2. The manuscript does not mention the verification of essential assumptions for the use of the t-test, such as normality (e.g., Shapiro-Wilk test) and homogeneity of variances (e.g., Levene test). Without this information, the validity of the statistical results is questionable.
4.3. The Intraclass Correlation Coefficient (ICC) was used to assess test-retest reliability, but the low reliability observed (values ranging from 0.42 to 0.74) compromises the robustness of the results. In addition, the ICC is sensitive to small sample sizes, resulting in wide confidence intervals.
4.4. The effect size measure was used to quantify the differences between the techniques, but in such a small sample it can produce unreliable estimates. This is of particular concern when the effect is used to support conclusions.
4.5. Before any statistical testing, I recommend increasing the number of participants to increase the statistical power and reliability of the results. If increasing the sample size is not feasible, I recommend using nonparametric tests, such as the Wilcoxon U test, to deal with potential violations of statistical assumptions.
4.6. Another recommendation is to use resampling methods (bootstrapping) to generate more reliable confidence intervals and reduce the dependence on the small sample size.
4.7. Have you considered using linear mixed models to assess intra- and inter-individual variability, rather than relying solely on simple mean comparisons? In this sense, if multiple analyses are performed, it is essential to apply corrections for multiple comparisons, such as Bonferroni or FDR, to reduce the risk of type I errors.

5. Results and Interpretation
5.1. Although the negative velocity was statistically significant, the low test-retest reliability compromises the results. Do you plan to perform additional tests or repeat the analysis to strengthen these findings?
5.2. The conclusions are based on small sample size and data collected with low-frequency equipment. How can you adjust the text to more clearly reflect these limitations?

6. References and Citations
6.1. Check that all references follow the MDPI format, ensuring consistency of citation style in the text and the reference list.
6.2. Some references may be out of date or not directly related to the main topic. I suggest including more recent studies, especially to support discussions of biomechanical methods and recording techniques.
6.3. Some sections make general statements without adequate citation support. For example, when discussing 'impact forces' and 'kinematics', include relevant references to support your statements.

7. Manuscript Structure
7.1. Reorganize the abstract to include a balance of objectives, methods, results, and conclusions, eliminating redundancies and ensuring a clear and concise presentation.
7.2. Make the introduction more focused on the central problem, avoiding overly general information about judo.
7.3. Make sure that the conclusions are consistent with the limitations mentioned.

8. Minor Points and Additional Suggestions
8.1. If it is not possible to correct some of the limitations in this version, we recommend that these points be discussed in more detail in the limitations section. For example, the inadequate definition of 'impact' and the low recording frequency could be discussed in more detail, emphasizing the impact of these issues on the validity and reproducibility of the study.
8.2. Consider revising the text to standardize formatting, correct typographical errors, and improve overall clarity.
8.3. Consider including a brief section or comment in the discussion on how the results can be used to improve training or reduce injuries in judokas.
8.4. If possible, provide clear suggestions for future studies, such as the use of more advanced technologies or more representative samples.

Comments on the Quality of English Language

Line 40 (Page 1): The term "[2men9]" appears to be a typographical error or poorly formatted reference. Replace or clarify the meaning.

Lines 78-85 (Page 2): The presentation of the questions contains inadequate spacing between the numbers and the text, making it difficult to read.

Introduction (Page 1, lines 33-39): Some passages have an excessively long sentence structure with unclear connectors.

Methodology (Page 3, lines 96-126): The paragraph describing the participant recruitment and consent process contains repetitive information. Reorganization is needed to make the text more straightforward.

Page 4, lines 138-143: The description of the camera setup and recording environment is incomplete. Consider including more details about calibration and control of external variables (such as lighting), as well as revising the grammatical structure.

Page 5, lines 183-185: The definition of impact is vague and not well articulated. It is suggested that it be revised and clarified to avoid ambiguities.

Results (Page 6, lines 223-226): The tables mentioned lack consistency in the wording of their titles. Standardize the nomenclature and avoid unexplained abbreviations.

Page 9, lines 350-359: The conclusion contains excessively complex sentences. I recommend a revision to increase objectivity and simplify the text.

Author Response

1. Textual Problems

1.1. Line 40 – "Fragment [2men9]" appears to be a typographical error or poorly formatted reference.

Response: Thank you for pointing this out. The typographical error has been corrected, and the reference has been verified and formatted according to MDPI requirements.

1.2. Lines 78–85 – Insufficient spacing between question numbers.

Response: Spacing between question numbers and text has been adjusted to improve readability.

1.3. Sections contain inconsistent spacing and formatting, such as Figures 2 and 3.

Response: The spacing and formatting have been standardized throughout the manuscript, including for Figures 2 and 3.

1.4. Figure 4 requires a higher resolution.

Response: A higher-resolution version of Figure 4 has been provided in accordance with the publisher’s requirements.

1.5. The tables have inconsistencies with the MDPI model, such as missing title lines and excess lines in Table 1.

Response: The formatting of tables has been adjusted to align with MDPI standards. Title lines have been added, and excess lines in Table 1 have been removed.

2. Methodology and Equipment

2.1. Lack of information on compliance of software (Kinovea and SPSS) and equipment with ICMJE standards.

Response: The methodology section has been updated to include information about the validation of Kinovea and SPSS based on previously published studies.

2.2. Recording at 30 Hz is insufficient for precise kinematic analysis.

Response: The limitations section discusses the impact of the 30 Hz frequency on the results. The rationale for selecting this frequency is explained, and future studies with higher-frequency equipment are proposed.

2.3. The definition of "impact" is unclear.

Response: The definition of "impact" has been clarified and standardized as "the moment of the first contact of uke’s shoulder with the mat."

3. Sampling and Generalizability Issues

3.1. Small sample size (6 participants).

Response: The sample size has been justified using statistical analyses and references to similar studies. It is acknowledged in the "Limitations" section that larger samples are recommended for future research.

3.2. Lack of female participants limits the generalizability of the results.

Response: We plan to include female participants in future studies to better understand gender-based kinematic differences.

3.3. Lack of weight category control compromises pairwise comparisons.

Response: The limitations of the study due to differences in participants' weights are discussed in the "Limitations" section.

4. Statistical Analysis

4.1. Limited statistical power of the t-test due to the small sample size.

Response: The limitations section highlights that the t-test may lead to Type II errors with a small sample. The use of nonparametric tests is recommended for future research.

4.2. Lack of verification of t-test assumptions.

Response: Information about the use of the Shapiro-Wilk test (normality) and Levene’s test (homogeneity of variance) has been added to the manuscript.

4.3. Low test-retest reliability.

Response: The low test-retest reliability is discussed in the "Limitations" section, emphasizing the need for larger samples and advanced statistical models.

4.4–4.7. Alternative statistical methods.

Response: The potential use of nonparametric methods, bootstrapping, and mixed models for future studies has been outlined to improve reliability and robustness.

5. Results and Interpretation

5.1. Low test-retest reliability for negative velocity.

Response: The results of negative velocity have been discussed in the context of test-retest limitations and the small sample size.

5.2. Incorporating limitations into the conclusions.

Response: The conclusions section has been expanded to clearly reflect the limitations related to the small sample size and recording frequency.

6. References and Citations

6.1–6.3. Verification of reference formatting and updating citations.

Response: All references have been checked for compliance with MDPI formatting standards. Newer and more relevant references have been added to support the discussion.

7. Manuscript Structure

7.1–7.3. Improving the abstract, introduction, and conclusions.

Response: The abstract has been reorganized to better balance objectives, methods, results, and conclusions. The introduction is now more focused on the central problem, and the conclusions address the study’s limitations more explicitly.

8. Minor Points and Additional Suggestions

8.1. Detailed discussion of limitations.

Response: The limitations section has been expanded to include detailed discussions of issues such as the definition of "impact" and the recording frequency.

8.2–8.4. Improving text clarity and future directions.

Response: The text has been revised to improve formatting, correct typographical errors, and enhance clarity. Suggestions for future studies, including advanced technologies and more representative samples, have been added.

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Dear authors,

Thank you for considering the suggested changes. The overall manuscript has been improved.

Kindest regards

Author Response

Thank You 

Reviewer 2 Report

Comments and Suggestions for Authors

Congratulations to the authors on the publication of the paper, many thanks to the authors for their contribution to the industry, and the revision of the corresponding content, I ultimately only feel that the Statistical Analysis part of the lack of necessary literature, recommended citation DOI: 10.3390/nu15030582 “Synergistic Effect of Rhodiola rosea and Caffeine Supplementation on the Improvement of Muscle Strength and Muscular Endurance: a Pilot Study for Rats, Resistance Exercise- Untrained and -Trained Volunteers”

Author Response

Dear Reviewer,  

Thank you very much for your kind words and recognition of our article. We greatly appreciate your attention to the section on statistical analysis and your suggestion to enhance the literature.  

In light of your recommendation, we will make the necessary revisions to the manuscript.  

 

Your Sincerly,

dr Łukasz Rydzik 

Reviewer 4 Report

Comments and Suggestions for Authors

The reviewer did not see any responses or modifications to the last comment on the system and related attachments, please check. Additional comments: Figure 4 is too vague, please adjust it. It is recommended that the results be presented as a picture. Also, please just highlight the changes in red, it is difficult to recognize the changes in the current version. For subheadings in the discussion section, please label them in order.

Comments on the Quality of English Language

no

Author Response

Dear Reviewer,

Thank you for your valuable comments, which have greatly contributed to improving our manuscript. Below are our responses to each of your remarks and explanations of the changes made:

1. "The reviewer did not see any responses or modifications to the last comment on the system and related attachments, please check."
   All points from the previous comment have been thoroughly reviewed, and the necessary modifications have been made. The changes have been highlighted in red throughout the manuscript for easy identification.

2. "Figure 4 is too vague, please adjust it. It is recommended that the results be presented as a picture."
   Figure 4 has been revised in accordance with your suggestions. It now presents the results in a graphical format, improving its clarity and facilitating interpretation.

3. "Please just highlight the changes in red, it is difficult to recognize the changes in the current version."
   All changes in the manuscript have been clearly highlighted in red to make them easily recognizable.

4. "For subheadings in the discussion section, please label them in order."
   Subheadings in the "Discussion" section have been labeled in order to enhance the organization and readability of the content. The updated structure is as follows:

   • 4.1. Biomechanical Analysis of Throws
   • 4.2. Impact Forces and Injury Risks
   • 4.3. Limitations and Future Research

5. Addition of graphs to the Results section:
   To better illustrate the findings, new graphs (Figures 5 and 6) have been added to the "Results" section. These graphs visually present the comparisons of peak acceleration and peak negative velocity values for the analyzed techniques, making the biomechanical differences between them easier to understand.

We hope the changes meet your expectations. Thank you again for your constructive feedback, and we remain open to any further suggestions.

Sincerely,
dr Łukasz Rydzik 

Reviewer 5 Report

Comments and Suggestions for Authors

Dear Authors,

Thank you for resubmitting your manuscript entitled "Video-biomechanical analysis of the shoulder kinematics of impact from Sode Tsurikomi Goshi and Tsurikomi Goshi judo throws in elite adult judoka."

I commend your efforts to address the feedback provided during the initial review. The improvements in your manuscript are evident, particularly in the organization of the results, the clarity of tables and figures, and the expanded discussion of certain methodological aspects.

However, there are still areas where further refinement is required to strengthen the scientific rigor and overall clarity of your study. Below, I outline my new feedback and improvement recommendations.

1. While the definition of "impact" was improved, it remains somewhat vague and may lead to misinterpretation. Please, consider providing a more explicit definition.

2. Your conclusions are based on a sample of six male judokas. While the limitations section mentions this, a deeper discussion of how this impacts the generalizability of the findings is necessary.

3. Although Kinovea and SPSS have been identified as validated tools, ICMJE compliance is required. Please correct the presentation of these programs and any equipment used in the research. These guidelines are available at https://www.icmje.org/icmje-recommendations.pdf

4. The 30 Hz recording frequency remains a critical limitation for capturing rapid kinematic movements. Although discussed, it is essential to elaborate further on how this limitation may have impacted the accuracy of acceleration and velocity measurements.

5. Although the paired t-test was used appropriately, the small sample size limits statistical power and increases the likelihood of Type II errors. I suggest using nonparametric tests, such as the Wilcoxon signed-rank test, or bootstrapping methods to obtain more robust confidence intervals. On the other hand, if you prefer to retain parametric tests, I recommend exploring potential interaction effects using linear mixed models given the biomechanical complexity of the techniques analyzed.

6. While Cohen’s d is reported, it would be helpful to contextualize the effect size values within the practical implications of judo training. Your results made me wonder about this. For example, does a "large" effect size in negative velocity translate to a meaningful difference in injury risk?

7. The results could be further clarified with the inclusion of diagrams or schematic illustrations that differentiate kinematic patterns between Sode-Tsurikomi-Goshi and Tsurikomi-Goshi. This is possible?

8. The discussion surrounding test-retest reliability (ICC values) would benefit from more depth. Please, address why the reliability for Tsurikomi-Goshi is moderate (ICC=0.60) and how this variability may affect the study’s conclusions.

In my opinion, your revised manuscript represents a notable improvement, addressing several concerns raised by me during the first review. However, I recommend a revision focusing on the points outlined above to further strengthen the study’s contribution. Finally, I look forward to reviewing the next version of this promising study.

Comments on the Quality of English Language

The second version of the manuscript is understandable and follows a basic academic structure, but further improvements in flow, grammatical consistency, and terminological accuracy are needed.
1. Break down complex sentences: avoid long, multi-clause sentences to improve clarity and readability.
2. Standardize terms: consistently define and use terms such as "impact" and "negative velocity."
3. Formalize tone: replace conversational phrases with academic equivalents.
4. Proofreading: engage a native English editor for final polishing to eliminate minor inconsistencies.

Suggestions:
Page 1, Lines 39–41 simplify to: "Judo, introduced by Kano Jigoro in 1864, became an Olympic sport in 1964..."
Lines 48–57 adjust to: "The risk of musculoskeletal injuries in judo is higher compared to other sports, such as soccer and wrestling, due to the high-impact nature of throws."
Page 4, Lines 138–143 revise to: "A one-meter calibration marker was placed at a safe distance from the throwing area for measurement accuracy."
Lines 161–167 consider breaking into two sentences for readability: "All participants practiced consistent techniques as members of The Aris Judo Club. This ensured uniformity in training style, though it may limit the generalizability of the findings."
Page 10, Lines 393–398 rephrase to: "According to Newtonian physics, acceleration and velocity are proportional to impact forces."
Lines 403–409 clarify that: "Discrepancies between acceleration and negative velocity results likely reflect differing biomechanical demands inherent to each technique."
Page 12, Lines 417–420 revise to: "Our findings suggest that the statistically significant differences in velocity between throws indicate greater velocity may correspond to increased impact forces."

Author Response

Dear Reviewer,

Thank you for your valuable feedback and for acknowledging the improvements made in our manuscript. We appreciate your thoughtful suggestions, which have further guided us in refining the scientific rigor and clarity of our study. Below, we provide detailed responses to each of your comments:

1. Definition of "impact":
Comment: While the definition of "impact" was improved, it remains somewhat vague and may lead to misinterpretation. Please, consider providing a more explicit definition.
Response: The definition of "impact" has been revised to explicitly describe the moment and conditions of initial shoulder contact with the tatami. The revised text provides a clear and consistent explanation to avoid ambiguity. Changes have been made in the "Materials and Methods" section, where "impact" is now defined as "the initial point of contact between uke's shoulder and the tatami, measured visually as the moment when maximum force transfer occurs during the throw."

2. Discussion of generalizability due to sample size:
Comment: Your conclusions are based on a sample of six male judokas. While the limitations section mentions this, a deeper discussion of how this impacts the generalizability of the findings is necessary.
Response: The "Limitations" section has been expanded to address how the small sample size affects the generalizability of the findings. We emphasize that while the study provides valuable insights into shoulder kinematics, the limited number of participants (and absence of female athletes) restricts the applicability of results to broader judo populations. Suggestions for future research include recruiting a larger, more diverse sample across different skill levels and competitive backgrounds.

3. ICMJE compliance for software and equipment:
Comment: Although Kinovea and SPSS have been identified as validated tools, ICMJE compliance is required.
Response: The descriptions of Kinovea and SPSS have been revised to meet ICMJE guidelines. The updated text provides clear details on the software’s version, validation, and relevance to sports biomechanics research. References to the ICMJE recommendations are included to ensure compliance.

4. Impact of 30 Hz recording frequency on measurement accuracy:
Comment: Elaborate further on how this limitation may have impacted the accuracy of acceleration and velocity measurements.
Response: The discussion has been expanded to explain that the 30 Hz recording frequency might have underestimated peak kinematic events due to insufficient resolution for rapid movements. We discuss how this limitation could introduce measurement error, particularly in high-velocity scenarios, and suggest that future studies use higher-frequency cameras (e.g., 120 Hz or more) for improved accuracy.

5. Statistical analysis and small sample size:
Comment: Suggest using nonparametric tests or bootstrapping methods for more robust confidence intervals. Alternatively, consider linear mixed models.
Response: While the paired t-test was used appropriately, we have now conducted additional analyses using the Wilcoxon signed-rank test and bootstrapping methods to validate our results. These analyses confirmed the trends observed with parametric tests. A discussion of the potential for interaction effects and variability has been added, highlighting the utility of linear mixed models in future studies.

6. Contextualizing Cohen’s d values:
Comment: Contextualize the effect size values within the practical implications of judo training.
Response: A new subsection in the "Discussion" highlights how the large effect size for negative velocity may correspond to increased injury risks during TG throws. We discuss the potential biomechanical and practical implications for judo training, including injury prevention strategies and technical adjustments.

7. Additional diagrams or schematic illustrations:
Comment: Include diagrams or schematic illustrations to differentiate kinematic patterns between STG and TG.
Response: New diagrams have been added to visually differentiate the kinematic patterns of Sode-Tsurikomi-Goshi and Tsurikomi-Goshi throws. These illustrations highlight key differences in shoulder acceleration and velocity between the techniques, improving the clarity of the results.

8. Test-retest reliability (ICC values):
Comment: Address why the reliability for Tsurikomi-Goshi is moderate and how this variability may affect conclusions.
Response: The discussion on test-retest reliability has been expanded to explain the moderate ICC for TG (0.60). We attribute this variability to the increased technical complexity and dynamic adjustments required during TG throws. These factors are acknowledged as potential sources of variability and are discussed in relation to the study’s conclusions.

Comments on the Quality of English Language

General Improvements:

1. Breaking down complex sentences: Long sentences have been simplified to improve readability.
2. Standardizing terms: Terms such as "impact" and "negative velocity" have been clearly defined and consistently used throughout the manuscript.
3. Formalizing tone: Conversational phrases have been replaced with appropriate academic equivalents.
4. Proofreading: A native English editor has been engaged to polish the manuscript, ensuring grammatical consistency and eliminating minor errors.

Examples of Specific Revisions:

• Page 1, Lines 39–41: Simplified to "Judo, introduced by Kano Jigoro in 1864, became an Olympic sport in 1964 and is now practiced by over 20 million people worldwide."
• Page 4, Lines 138–143: Revised to "A one-meter calibration marker was placed at a safe distance from the throwing area to ensure measurement accuracy."
• Page 10, Lines 393–398: Rephrased to "According to Newtonian physics, acceleration and velocity are proportional to impact forces."

We hope these revisions address your concerns and meet the expectations for scientific rigor and clarity. Thank you for your valuable feedback, which has greatly contributed to improving our study. We look forward to your evaluation of this revised manuscript.

Sincerely,
dr Łukasz Rydzik