Standardization and Utilization of Lower Limb Single Joint Isometric Force Plate Assessments and Recommendations for Future Research

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Add an explicit description of the review method (search criteria, inclusion/exclusion).

 Strengthen the empirical basis for key statements (footwear, sampling frequency).

Correct typographical errors and standardise references.

Incorporate quantitative values (ICC, CV, n of studies) where reliability is mentioned.

Add a final conclusion that connects the recommendations with sports and clinical practice.

Comments for author File: Comments.pdf

Author Response

Thank you for your review and points identified and the opportunity to resubmit following minor amendments. Please see point by point response below.

Add an explicit description of the review method (search criteria, inclusion/exclusion).

The review is narrative in nature and therefore does not include a methods section (including search criteria and inclusion/exclusion), we have tried to make it clear in the purpose by stating it as a narrative review.

 Strengthen the empirical basis for key statements (footwear, sampling frequency).

Thank you for this point, however, we are not sure what the reviewer is referring to as we clearly use appropriate references for the sampling frequency and to date minimal research has published on the use of footwear. We have included further references to support from other areas however, it is purely speculative on it’s effect on other tasks.

Correct typographical errors and standardise references.

Thank you, we have made typographical changes based on specific comments on other reviewers. Hopefully, this is now appropriate.

Incorporate quantitative values (ICC, CV, n of studies) where reliability is mentioned.

As per the initial comment as this is a narrative review, it is difficult to ascertain such information. The aim of this review is to be useable by practitioners and therefore this level of detail may negate such aspects.

Add a final conclusion that connects the recommendations with sports and clinical practice.

We have attempted to improve the conclusion to provide better connection to the sports and clinical practise. It is hoped that the SOP figures do provide this practise based recommendation.

Reviewer 2 Report

Comments and Suggestions for Authors

Thank you for the opportunity to review this manuscript. I found it to be clear and well-written, covering critical information for the use of force plates for isometric testing of single-joint actions involving the hamstrings and plantar flexors. The information is very useful, with sound, evidence-based recommendations stemming from the past work on both these specific tests and related forms of testing.

 

I do not have any critiques of the content in this manuscript. I believe it is accurate and comprehensive enough for covering the topic and providing recommendations. This will be a valuable manuscript for researchers, sport scientists, and coaches who are or who will be employing these types of tests, improving the accuracy, validity, and reliability of the data they obtain. There are a few sentence structure and grammatical issues that should be fixed, but this can be accomplished quickly and easily.

 

Specific comments:

 

Lines 46-47, Fix grammar of this sentence: “The hamstrings have an integral role in ACL rehabilitation they are the most frequently assessed muscle group using single joint isometric assessment [6,7,11,13,14,17-22], followed by plantar flexors [12,23,24].”

 

Line 80, Fix grammar – “reliability associated with test design used”

 

Line 99, fix grammar – “have used cue…”

 

Line 247-248 – sentence fragment

 

Lines 253-255 – sentence fragment

 

Line 308 – need additional comma for “flat stable, solid surface”

 

Line 440 – should be “collect data effectively and accurately”

 

Lines 440-443 – sentence needs rewording for clarity and correct grammar

Author Response

Thank you for your thorough review and positive comments regarding the manuscript and we hope the same with regards the application of the manuscript to practise.

Thank you for the opportunity to review this manuscript. I found it to be clear and well-written, covering critical information for the use of force plates for isometric testing of single-joint actions involving the hamstrings and plantar flexors. The information is very useful, with sound, evidence-based recommendations stemming from the past work on both these specific tests and related forms of testing.

I do not have any critiques of the content in this manuscript. I believe it is accurate and comprehensive enough for covering the topic and providing recommendations. This will be a valuable manuscript for researchers, sport scientists, and coaches who are or who will be employing these types of tests, improving the accuracy, validity, and reliability of the data they obtain. There are a few sentence structure and grammatical issues that should be fixed, but this can be accomplished quickly and easily.

Specific comments:

Lines 46-47, Fix grammar of this sentence: “The hamstrings have an integral role in ACL rehabilitation they are the most frequently assessed muscle group using single joint isometric assessment [6,7,11,13,14,17-22], followed by plantar flexors [12,23,24].”

Thank you for noting this, this has been amended.

Line 80, Fix grammar – “reliability associated with test design used”

Thank you for noting this, this has been amended.

Line 99, fix grammar – “have used cue…” 

Thank you for noting this, this has been amended.

Line 247-248 – sentence fragment 

Thank you for noting this, this has been amended.

Lines 253-255 – sentence fragment 

Thank you for noting this, this has been amended.

Line 308 – need additional comma for “flat stable, solid surface”

Thank you for noting this, this has been amended.

Line 440 – should be “collect data effectively and accurately”

Thank you for noting this, this has been amended.

Lines 440-443 – sentence needs rewording for clarity and correct grammar

Thank you for noting this, this has been amended.

Reviewer 3 Report

Comments and Suggestions for Authors

English usage: While generally clear, the manuscript occasionally includes long and complex sentences that may hinder comprehension (pg. 2, lines 38–42).

• Example: “Force plates can be used across a range of dynamic and isometric multi-joint and single joint tasks to provide valid and reliable accurate assessment of force-time characteristics.” This could be revised for clarity.

Referencing style: The formatting of some in-text references is inconsistent. In several places, the same references are repeated without adding new context (11,13,14 appears repeatedly). Consider condensing or citing selectively when appropriate.

Figures and tables: Table 1 is dense and could benefit from better visual formatting (clearer column delineation, removal of redundant notations).

Raw data: Although not expected in a narrative review, no mention is made of any supplementary materials. Consider including supplementary templates or example SOPs if feasible in future iterations.

Replicability and transparency: While the authors describe existing protocols and their reliability, the review could benefit from more explicit tables or appendices summarizing standardized recommendations (e.g., standard cueing language, setup dimensions, sampling frequency, fixation angles). For instance, on page 4, lines 122–135, the cueing discussion is critical but would be more practical if distilled into a table.

Bias and scope: The review draws heavily from the authors’ own work (notably Ripley et al., Comfort et al., Fahey et al.). Although these are relevant and foundational, a broader inclusion of external sources would help balance the narrative.

Footwear and fixation discussion: Important methodological details are addressed (e.g., pg. 3, lines 110–121), but experimental data on their effects are lacking. This is acknowledged, but the manuscript could be strengthened by suggesting controlled studies or pilot protocols.

Comparative data missing: While the review refers to reliability data across positions (90:90 vs. 30:30), there is limited discussion of normative values or ranges across sports or populations — a limitation acknowledged in Table 3 but worthy of greater emphasis.

Interpretive caution: On page 5 (lines 194–199), the review discusses early RTD as a more sensitive fatigue marker than peak force, which is promising but still preliminary. Authors should emphasize that practical application requires careful contextualization and validation.

Practical implementation: The conclusions could be expanded by discussing barriers to implementation in real-world settings (cost of force plates, staff training, athlete compliance).

Clinical implications: The role of isometric assessments in clinical populations (ACLR, older adults) is mentioned in passing but deserves further elaboration. For example, which protocols are most feasible in a rehabilitation setting?

 

Page 2, lines 42–44: Please clarify the statement “determine potential injury risk, identifying training needs and monitoring fatigue.” Which specific metrics and thresholds are suggested for each?

Page 3, Table 1: Improve formatting and clarity (break down rows visually, explain symbols such as ✓, x, ? more clearly).

Page 4, lines 122–135: Consider creating a table summarizing recommended cueing instructions for each test variation (“Push hard and fast” vs. “Push fast and hard”).

Page 6, Figure 2: If possible, enhance the resolution and labeling of figures for readability. Define all abbreviations in the caption.

Throughout: Moderate the dominance of the authors’ own publications by incorporating more external literature, especially regarding plantar flexor assessments and clinical utility.

Add a table or summary of practical SOP recommendations: include setup positions, sampling frequency, cueing, fixation strategies, footwear recommendations, etc.

Author Response

Thank you for your comprehensive review and points identified and the opportunity to resubmit following minor amendments. Please see point by point response below.

English usage: While generally clear, the manuscript occasionally includes long and complex sentences that may hinder comprehension (pg. 2, lines 38–42).

• Example: “Force plates can be used across a range of dynamic and isometric multi-joint and single joint tasks to provide valid and reliable accurate assessment of force-time characteristics.” This could be revised for clarity.

Thank you for noting this, we have now amended throughout the manuscript.

Referencing style: The formatting of some in-text references is inconsistent. In several places, the same references are repeated without adding new context (11,13,14 appears repeatedly). Consider condensing or citing selectively when appropriate.

Thank you for noting this, we have now amended throughout the manuscript.

Figures and tables: Table 1 is dense and could benefit from better visual formatting (clearer column delineation, removal of redundant notations).

Thank you for noting this; although we acknowledge it is a lot of information however, we feel for a narrative review for practitioners it has visual impact that is clear with the use of ticks, crosses for practitioners to interpret. We have tried to improve the formatting to make the information presented clearer.

Raw data: Although not expected in a narrative review, no mention is made of any supplementary materials. Consider including supplementary templates or example SOPs if feasible in future iterations.

Thank you for this interesting comment, initially, we considered not following this up due to the complexities and considerations but upon further consideration we have provided an example SOP for supplementary material for practitioners.

Replicability and transparency: While the authors describe existing protocols and their reliability, the review could benefit from more explicit tables or appendices summarizing standardized recommendations (e.g., standard cueing language, setup dimensions, sampling frequency, fixation angles). For instance, on page 4, lines 122–135, the cueing discussion is critical but would be more practical if distilled into a table.

Thank you for this comment, due to the scarcity of literature in this area we have decided not to include a further table based on the text included. However, we hope the example SOPs provided do clearly identify.

Bias and scope: The review draws heavily from the authors’ own work (notably Ripley et al., Comfort et al., Fahey et al.). Although these are relevant and foundational, a broader inclusion of external sources would help balance the narrative.

Thank you for noting this, while we agree there is self-citations we do not this think this falls outside of the scope of the present study. This was also acknowledged by the editor. We have in turn based on recommendations for yourself increased the citations from other sources which are non-related to force plates (e.g., utilising isokinetic dynamometry) to provide further external support. Additionally, we have removed some of the less relevant references where Comfort is a middle author. It is important to note the fact that a narrative style review draws on from our work which is not surprising as we are the most published research group in this area and we want to provide this information to the practitioners.

Footwear and fixation discussion: Important methodological details are addressed (e.g., pg. 3, lines 110–121), but experimental data on their effects are lacking. This is acknowledged, but the manuscript could be strengthened by suggesting controlled studies or pilot protocols.

Thank you for noting this, we have made the relation to future research clearer on these two elements. We have also tried to strengthen the empirical positions on these factors using evidence from other aspects of performance (e.g., effect of footwear on peak forces during running and effect of fixation on isokinetic knee flexor assessments).

Comparative data missing: While the review refers to reliability data across positions (90:90 vs. 30:30), there is limited discussion of normative values or ranges across sports or populations — a limitation acknowledged in Table 3 but worthy of greater emphasis.

Thank you for noting this we have provided further discussion on normative values for hamstring and plantar flexor assessments.

Interpretive caution: On page 5 (lines 194–199), the review discusses early RTD as a more sensitive fatigue marker than peak force, which is promising but still preliminary. Authors should emphasize that practical application requires careful contextualization and validation.

Thank you for noting this we have made it clearer around the validation of claims, as this is based purely on two studies albeit from the test design.

Practical implementation: The conclusions could be expanded by discussing barriers to implementation in real-world settings (cost of force plates, staff training, athlete compliance).

Thank you for noting this we have attempted to expand the conclusion without losing the application of the SOP element.

Clinical implications: The role of isometric assessments in clinical populations (ACLR, older adults) is mentioned in passing but deserves further elaboration. For example, which protocols are most feasible in a rehabilitation setting?

Thank you for noting this, we have tried to enhance this aspect (although as expected there is limited information upon this) and hope the changes are sufficient.

Page 2, lines 42–44: Please clarify the statement “determine potential injury risk, identifying training needs and monitoring fatigue.” Which specific metrics and thresholds are suggested for each?

We have provided a clearer explanation for each factor, however, much of the information (e.g., metric and thresholds) is provided in the text and should not be introduced so early in the manuscript.

Page 3, Table 1: Improve formatting and clarity (break down rows visually, explain symbols such as ✓, x, ? more clearly).

We have tried to improve the formatting and clarity of the table, however, we are reluctuant to make larger changes as if we do so it would require the inclusion of substantially more tables requiring reducing the accessibility to practitioners. Additionally, following positive feedback from previous presentations we want to retain this table.

Page 4, lines 122–135: Consider creating a table summarizing recommended cueing instructions for each test variation (“Push hard and fast” vs. “Push fast and hard”).

Thank you for this suggestion, as previously identified on an earlier comment there is a scarcity of research in this area and a table would likely be redundant as all cues need investigation. Only Rasp et al., who added a vector component to the cue rather than maximal or rapid force production element. We are taking suggestions from multi-joint assessments (i.e., isometric mid-thigh pull); we have not suggested this within the text. But we do not feel there is sufficient information to develop a table based on the published information.

Page 6, Figure 2: If possible, enhance the resolution and labeling of figures for readability. Define all abbreviations in the caption.

The resolution matches journal requirements, if the reviewers could identify which abbreviations need defining within the figures will be useful.

Throughout: Moderate the dominance of the authors’ own publications by incorporating more external literature, especially regarding plantar flexor assessments and clinical utility.

Thank you for noting this, as per previous comments we have toned down the use of own publications. It is important to note, that the author who appears most frequently (Comfort) has over 300 publications with a predominant focus around the use of force assessment in different populations. Therefore, it would be hard not to cite some of his work, even if he is only a co-author, moreover, it would also not make sense to exclude Comfort due to his prominence in the area as he is an expert in the area the narrative review is discussing.

Add a table or summary of practical SOP recommendations: include setup positions, sampling frequency, cueing, fixation strategies, footwear recommendations, etc.

Thank you for noting this, unfortunately and as the information presented in the review highlights clear guidance on an SOP is impossible currently provide without considerations (presented in figure 1 and 2) and further research (presented in table 3). As per your previous suggestions we have provided an example SOP within the supplementary material for readers to use and potentially adapt to their own considerations. We hope this addition is sufficient in the practical application of an SOP.

Reviewer 4 Report

Comments and Suggestions for Authors

1. Insufficient Standardization Guidelines：While the review comprehensively summarizes current single-joint isometric assessment methods, it lacks clear differentiation between standardized protocols for laboratory versus applied settings (e.g., joint angles, fixation methods, sampling frequencies).
2. Limited Reliability Analysis：Reliability data for key metrics (e.g., CV/ICC for RFD 0-100 ms) are incomplete or absent in Table 1, undermining conclusions.
3. Inadequate Biomechanical Rationale：The impact of "system mass" differences (e.g., standing vs. kneeling) on force transmission dynamics lacks mechanistic explanation.
4. Underexplored Practical Limitations：Real-world constraints (e.g., uniaxial force plates, device accessibility, operator expertise) are insufficiently addressed.
5. Vague Future Directions：Future research directions should be more specific. It is recommended to reduce redundancy in Table 3 by merging similar types of suggestions, as the current research methodologies are expressed too broadly. Please provide updated and concrete research methods.

Author Response

Thank you for your review and points identified and the opportunity to resubmit following minor amendments. Please see point by point response below.

1. Insufficient Standardization Guidelines：While the review comprehensively summarizes current single-joint isometric assessment methods, it lacks clear differentiation between standardized protocols for laboratory versus applied settings (e.g., joint angles, fixation methods, sampling frequencies).

Thank you for noting this, based on your review and previous reviewers comments we have further explored the standardization guidelines and provided an example of an standard operating procedure.

1. Limited Reliability Analysis：Reliability data for key metrics (e.g., CV/ICC for RFD 0-100 ms) are incomplete or absent in Table 1, undermining conclusions.

Thank you for noting this, we have further clarified the reliability using appropriate descriptors, however, as this is a narrative aimed at practitioners we wanted to retain an ability for easy interpretation. Hence, the lack of specific reliability values. We do not think it undermines the conclusions as these are clearly identified based on the context of the reliability which we have expanded upon.

1. Inadequate Biomechanical Rationale：The impact of "system mass" differences (e.g., standing vs. kneeling) on force transmission dynamics lacks mechanistic explanation.

Thank you for noting this we have provided a better mechanistic explanation for the lower system mass (please note we have also changed the term system mass for system weight for consistency within the manuscript).

1. Underexplored Practical Limitations：Real-world constraints (e.g., uniaxial force plates, device accessibility, operator expertise) are insufficiently addressed.

Thank you for noting this, while we have identified the real-world constraints further, with regards to technology availability and cost, and the associated considerations from practitioners. We feel we have explored these considerations, more over the inclusion of example standard operating procedures provides further practical application.

1. Vague Future Directions：Future research directions should be more specific. It is recommended to reduce redundancy in Table 3 by merging similar types of suggestions, as the current research methodologies are expressed too broadly. Please provide updated and concrete research methods.

Thank you for noting this, we have tried to improve the research questions with more clarity and reduced redundancy.

Round 2

Reviewer 4 Report

Comments and Suggestions for Authors

The authors have revised and improved the manuscript in accordance with the feedback provided previously and are in agreement with its acceptance for publication.