Test–Retest Reliability of Concentric and Eccentric Muscle Strength in Knee Flexion–Extension Controlled by Functional Electromechanical Dynamometry in Women’s Soccer

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Thank you for the opportunity to review this article. While it is important to have portable and affordable devices for evaluating muscle strenght, they have some limitations with respect to what is commonly know as the golden standard. That could be one of the major limitations of the results of this study if not taken into account (please see the specific comments provided bellow). The introduction is short, and research problem not well justified, whereas discussion is short and not conceptualized in the manner expected for this journal. Also, this study would be more impactfull if validity evaluation was provided. Taken all into account, I suggest major revisions.

Specific comments to the authors

Abstract:

Line 31: Please add Functional Electromechanical Dynamometer before the abbreviation (FEMD)

Line 32: Please provide age, mass and height of your participants. Are they amateurs or professional?

Lines 32-34: Please correct language and rewrite sentences for clarity.

Lines 35-35: Consider rewriting to better outline your results. You have good results, but presented this way does not have the intended impact on the reader. Also, please provide ICC and CV values separately for CON and ECC.

Lines 38-40: You have good results so consider rewriting the sentence to outline the practicability and good quality of measurements using FEMD

Main text:

Line 46: Delete the full stop before the reference parenthesis

Line 71: Respectfully, I do not understand the use of “dependability” in this sentence, since later on you provide findings of generally good (high) reliability across different tasks.

Lines 71-91: Consider rewriting these two paragraphs in such a way that you sumarize the findings of the mentioned studies with respect to motor tasks, contraction types, participants etc. It would facilitate understanding and help you make a transition to what has not been investigated – knee muscles strength during concentric and eccentric actions. Moreover, the mentioned studies are mostly conducted on healthy males of different training background thus lacking the investigation involving females and in particular those who play soccer.

Lines 98-100: Consider rewriting. Maybe something like: Based on previous research (REFERENCES), FEMD can be used as a reliable method for the evaluation of concentric and eccentric muscle strength of knee flexion and extension tasks.

Line 100-101: The improtance of the study needs to be better defined.

Methods:

Lines 105-106: so were they familiarization or data collection sessions? It seems that “laboratory familiarization” is unnecessary in this paragraph.

Lines 105-112: This paragraph needs to be rewriten. Please shortly describe protocol by providing details of each session. E.g., first session was used to assess anthropometry, to familiarize participants with measurement procedures and FEMD. Aftewards, participants commenced to experimental trials…..

Line 115: Change “Height” to “height”

Line 132: This should be called Warm-up protocol since that is what it is by the way you described it.

Line 144: Please provide details regarding FEMD, specifically “sensed load” (is this the load used to callibrate FEMD) and sampling frequency.

Line 152: What is the difference between the warm-up and familiarization?

Lines 156-158: Already provided in the Study Desing paragraph

Line 159: Please include Data acquisition and processing paragraph. Did you use a software provided with FEMD or a custom-made one? It is of improtance to provide details how muscle strength was evaluated considering the change in pulling angle across the range of motion (the angle between the shin and the cable). If this was not taken into account than the validity of the measurements is questionable.

Line 175: Remove parenthesis

Line 192: Is this a Hopkin`s reliability spreadsheet? If so, provide spreadsheet version and date when accessed.

Line 206: remove full stop with coma sign before As shown….

Lines 186-190 and 245-284: What was the rationale for including Pearson`s correlation coefficients into realiability analysis when you already have ICC?

Line 191: Respectfully, it is the measures of strength that are reliable, not the device.

Lines 299-301: This sentence has invalid logical contstruct. Study sample does not imply sport specificity.

Line 303: Is this the first study to evaluate knee flexion and extension in concentric and eccentric actions? If so, than emphasize that fact, on the other hand compare your findigns with previous research regarding FEMD and knee muscles strength.

Line 309: Remove “ Sánchez-Sánchez et al.” Since the reference was provided in the parenthesis.

Lines 305-311: The authors basically repeated the same as the text in lines 86-91.

Line 325: This statement is partly related to the comment regarding Line 159 and pulling angle so if this was not taken into account. In my moddest opinion, trustworthy includes both reliability and validity which this study does not have.

Line 329: Please explain what do you consider by “great dependability of FEMD”

Line 330: Respectfully, female sample by itself cannot be the single limitation of this study. Training history, competition level, validity evaluation,possibility of generalization of your findings ….

Conclusion is short and not emphasizing strong enough the bottomline of the research.

 

 

 

 

 

 

Comments on the Quality of English Language

Minor editing needed

Author Response

Dear reviewer: Along with greeting and thanking you for your comments, because they were very helpful in developing a manuscript of better quality and better understanding for the reader, I attach the response to your comments.

Regards

Comment 1: [Line 31: Add Functional Electromechanical Dynamometer before the abbreviation (FEMD)]

Response 1: [Added “functional electromechanical dynamometer” on line 32].

Comment 2: [Line 32: Please indicate the age, mass and height of the participants. Are they amateurs or professionals?].

Response 2: [The players are described as professionals and the age, weight, height and IBM are added on lines 32 and 33].

Comment 3: [Lines 32-34: Correct language and rewrite sentences for clarity].

Response 3: [Edited wording]

Comment 4: [Lines 35-35: Consider rewriting to better describe your results. You have good results, but presented this way they do not have the desired impact on the reader. Also, provide separate ICC and CV values ​​for CON and ECC].

Response 4: [was modified by “No significant mean differences were found in the test-retest analysis (p > 0.05; ES < 0.14), and high reliability was reported for peak muscle strength assessments in both the CON phase (ICC= 0.90 - 0.95 ) and the ECC phase (ICC= 0.85 - 0.97). Furthermore, stable repeatability was presented for extension in the CON phase (CV = 7.39-9.91%) and ECC phases (CV = 8.65-13.64)”].

Comment 5: Lines 38-40: [You have good results, so consider rewriting the sentence to summarize the feasibility and good quality of measurements using FEMD].

Response 5: [The main findings of this study show that maximal muscle strength in knee flexion and extension in the CON and ECC phase is a measure with acceptable absolute reliability and extremely high relative reliability using the FEMD in professional female soccer players].

Comment 6: [Line 46: Remove the period before the reference parenthesis].

Response 6: [Removed].

Comment 7: Line 71: [Respectfully, I do not understand the use of “reliability” in this sentence, as later on it provides findings of generally good (high) reliability across different tasks].

Response 7: [Modified to accept reviewer's comment from lines 73 to 77].

Comment 8: Lines 71-91: [Consider rewriting these two paragraphs in such a way that it summarizes the findings of the mentioned studies regarding motor tasks, types of contraction, participants, etc. This would make it easier to understand and help you transition to what has not been investigated: knee muscle strength during concentric and eccentric actions. Also, the mentioned studies are mostly performed on healthy men with different training backgrounds, so they lack the research involving women and in particular those who play soccer].

Response 8: [We will stick to the format that was implemented in the paragraph, because we have few words as instructed by the general editor, irrelevant information was removed, and more research was described].

Comment 9: [agree rewrite Maybe something like: Based on previous research (REFERENCES), the FEMD can be used as a reliable method for the assessment of concentric and eccentric muscle strength in knee flexion and extension tasks].

Response 9: [The paragraph was restructured].

Comment 10: [Line 100-101: The importance of the study needs to be better defined].

Response11: [added to lines 101 to 104 “Considering that most of the FEMD studies have been carried out on young male university students and there is little evidence on women and none on female soccer players”].

Methods:

Comment 11: [Lines 105-106: So these were familiarization sessions or data collection sessions? It seems that “familiarization in the laboratory” is unnecessary in this paragraph].

Response 11: [Paragraph modified at the suggestion of the editor].

Comment 12: [Lines 105-112: This paragraph should be rewritten. Briefly describe the protocol, giving details of each session. For example, the first session was used to assess anthropometry, to familiarize participants with the measurement procedures and the FEMD. Participants then began the experimental trials].

Response 12: [“Participants attended 2 familiarization sessions (at least 48 h apart) the first session was used to assess anthropometry, to familiarize participants with the measurement procedures and FEMD” was added at the recommendation of the reviewer on line 111 – 114].

Comment 13: [Line 115: Change “Height” to “height”]

Response 13: [Modified]

Comment 14: [Line 132: This should be called Warm-up Protocol, since that is what it is based on the way you described it].

Response 14: [The warm-up protocol on line 155 was added to the peak force sectio].

Comment 15: [Line 144: Please provide details on FEMD, specifically the “load detected” (is this the load used to calibrate FEMD?) and the sampling frequency].

Response 15: [The materials section was included in the methodology line 133 where the device selection properties are described in relation to load detection and the sensors used].

Comment 16: [Line 152: What is the difference between warm-up and familiarization?]

Response 16: [Warm-up and familiarization have been modified].

Comment 17: [Lines 156-158: Already provided in the Study Design paragraph.

Response 17: [Information was removed from the study design].

Comment 18: [Line 159: Please include the paragraph on data acquisition and processing. Did you use software provided with FEMD or custom software? It is important to provide details on how muscle strength was assessed by considering the change in angle of pull throughout the range of motion (the angle between the shin and the cable). If this was not taken into account, the validity of the measurements is questionable].   Response 18: [it was reported in line 169: “recording peak muscle strength values using software provided”, in response to the comment, the muscle strength was evaluated considering the distance the rope travels and the tension detected by the device's sensors].   Comment 19: [Line 175: Remove parentheses]   Response 19: [removed]   Comment 20: Line 192: Is this a Hopkin reliability spreadsheet? If so, please provide the version of the spreadsheet and the date it was accessed.   Response 20: The spreadsheet from the article was used. This is a downloadable Excel spreadsheet. Its validity and reliability are presented in the article Hopkins, W. Spreadsheets for analysis of validity and reliability. Sportscience 2015. 21, 36–44. sportsci.org/2015/ValidRely.htm  

Comment 21: [Line 206: Remove the semicolon before As shown….]

Response  21: [Removed]

Comment 22: [Lines 186-190 and 245-284: What was the reason for including Pearson correlation coefficients in the reliability analysis when the ICC is already available?]

Response 22: [To present an association analysis of the muscle strength assessments from both sessions]

Comment 23: [Line 191: Respectfully, it is the force measurements that are reliable, not the device].

Response 23: [Changed at the reviewer's suggestion to reword paragraph 291 to “The results of our study confirm that the assessment of peak muscle strength in knee flexion and extension, both concentrically and eccentrically, with FEMD is reliable.”]

Comment 24: [Lines 299-301: This sentence has an invalid logical construction. The study sample does not imply sport specificity].

Response 24: [Sentence is deleted].

Comment 25: [Line 303: Is this the first study to assess knee flexion and extension in concentric and eccentric actions? If so, please emphasize that fact and, on the other hand, compare your findings to previous research on FEMD and knee muscle strength].

Response 25: [Added to the discussion on line 329-333: “The assessment of peak muscle strength in knee flexion and extension is an assessment that has been performed with FEMD, and the population evaluated is female soccer players, a population that has “not been studied with FEMD, since most of the research previously conducted with FEMD is in young university students”].

Comment 26: [Line 309: Delete “Sanchez-Sanchez et al.” as the reference was provided in parentheses].

Response 26: [Modified].

Comment 27: [Lines 305-311: The authors basically repeated the same thing as the text on lines 86-91].

Response 27: [was modified by the paragraph on line 332: “Similar results to those of our study were obtained in the level of reliability in the study Sanchez-Sanchez et al. [23], which analyzed the peak muscle strength for the hamstring exercise protocol with eccentric swing at a displacement velocity of 0.4 m s-1 equal to that of this study”].

Comment 28: [Line 325: This statement is partly related to the comment on line 159 and the angle of pull, so if this was not taken into account, IMHO, reliability includes both reliability and validity, which this study does not have].

Response 28: [Device validity was analyzed in the study: Rodriguez-Perea et al. (2021). Reliability and concurrent validity of a functional electromechanical dynamometer device for the assessment of movement velocity: https://journals.sagepub.com/doi/full/10.1177/1754337120984883].

Comment 29: [Line 329: Please explain what you consider “high reliability of FEMD”

Response 29: [There was a typo in the wording, it was modified on line 351: “good reliability”].

Comment 30: [Line 330: Respectfully, the female sample alone cannot be the only limitation of this study. Training history, level of competence, validity assessment, generalizability of its findings].

Response 30: [modified in line 362: “Since training history at other levels of competition alternating in games was not considered, it is not possible to generalize our findings to all athletes in other sports. Future studies should be initiated that analyze different motor gestures of each sport in different populations and levels of competition”].

Comment 31: [The conclusion is brief and does not sufficiently emphasize the final result of the investigation].

Response 31: [modified on line 366 – 371: “The main result of our study reports that the evaluation of peak muscle strength in knee flexion and extension, both concentrically and eccentrically with FEMD, has relative and absolute reliability when evaluating professional female soccer players. This makes it easier to track the progress and development of female footballers by providing another, more affordable option for recording various manifestations of muscle strength and what it implies for the development of the skills specific to the sport].

Thank you very much. Best regards

Reviewer 2 Report

Comments and Suggestions for Authors

Dear Authors,

The article you submitted presents a clear and well-analyzed study. While it follows a distinct protocol, it shares some similarities with the article published in Sports 2024, 12, 175 (https://doi.org/10.3390/sports12070175).

The dynamometric measurement instrument is described with precise and rigorous characteristics regarding validation and calibration. However, in addition to this validation of the eccentric/concentric measurement protocol for knee flexion-extension, it would have been interesting to include a training protocol, such as strength training or running at a controlled speed, to better understand the impact of these practices on the evolution of the measurements.

Apart from this suggestion, which is more of a recommendation than a criticism, we have no significant concerns about the submitted article. However, a few points could be clarified and/or expanded upon:

p2, l73: Could you introduce the abbreviations (CV, ICC, etc.) when they are first mentioned?
p2, l73: What is the unit for ICC? If relevant, indicate "UI".
p3, l108: How is the speed of 0.4 m.s⁻¹ controlled? Is it imposed by the dynamometer? This is not explicitly mentioned in the text.
p3, l132: Could you provide more details about the familiarization protocol, particularly regarding the total warm-up duration? How is the reserve frequency calculated? Why did you choose 5% of body weight for the flexors and 10% for the knee extensors? Which studies inspired these percentage choices?
Thank you for your contribution, and we wish you continued success in your research.

Best regards,
PhC

Author Response

Dear reviewer, along with thanking you for your comments and corrections, I am sending the modifications included by you Greetings and very grateful.

Comment 1: [p2, l73: Could you present the abbreviations (CV, ICC, etc.) when they are first mentioned?]

Response 1: [Abbreviations are presented in the document].

Comment 2: [p2, l73: What is the unit of the ICC? If applicable, indicate "UI"

Response 2: [The ICC has no unit of measurement].

Comment 3: [p3, l108: How is the speed of 0.4 m.s⁻¹ controlled? Is it imposed by the dynamometer? This is not explicitly mentioned in the text].

Response 3: [The materials section is included, which describes the selection properties of the device in relation to the speed of movement of the rope].

Comment 4: [p3, l132: Could you provide more details on the familiarization protocol, in particular on the total duration of the warm-up?].

Response 4: [More background information on the warm-up phase was included in the muscle strength assessment section, line 157]

Comment 5: [How is heart rate reserve calculated?]

Response 5: [It was estimated using the formula Heart Rate Reserve = Maximum Heart Rate. – Resting Heart Rate was also monitored by a heart rate monitor].

Comment 6: [Why did you choose 5% of body weight for the knee flexors and 10% for the knee extensors? What studies inspired these percentage choices?].

Response 6: [Very low initial warm-up loads were chosen to prevent any muscle injuries].

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Congratulate on your work.