Exploring the Effect of Prolonged Ankle Plantar-Flexed Standing on Postural Control, Balance Confidence, Falls Efficacy, and Perceived Balance in Older Adults

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Thanks for the opportunity to review the paper " Exploring the effect prolonged ankle plantar-flexed standing on postural control, balance confidence, falls efficacy and perceived balance in older adults".

A pertinent and topical subject for older adults.

The review will be carried out in the order of the different sections, making the reading more perceptible.

Abstract

They should revise the entire methodology section, as it is not clear what type of study was carried out and where the participants came from.
Regarding the methodology, it is not clear what was carried out, the abstract was written for those who are familiar with the subject, not for those who are learning about it and reading it for the first time. The results lack the data needed to draw a conclusion. Nor does the conclusion respond to the proposed objectives.

The keywords should not be the same as those already in the title, please change them.

Introduction

The introduction does not justify the relevance of developing the study in question, and is very poor in its justification.
The objectives proposed in the introduction are not in line with those described in the abstract.

Materials and Methods 

We need to know which institution submitted the study, which ethics committee approved it and the registration number of the ethics committee's report.

The entire methodology needs to be reviewed and reformulated, since it is not clear what has been done, even in terms of the questionnaires to be filled in.

Results

The results as presented are very confusing.

Why there is no characterisation of the participants, several of their characteristics may help to explain the results found.

They must standardise the decimal places in the different tables.

The different tables lack legends for the different acronyms used.

Table 2 is not referenced in the text in the results section.

Discussion 

In this section you should discuss these questions: (1) How does prolonged activity affect postural control in older adults; (2) What evidence suggests that the plantar flexor muscles were fatigued; (3) What factors might explain the individual differences in postural control responses to prolonged activity; (4) How could future research improve upon the methods used in this study to better assess fatigue effects on postural control.

Conclusions 

The conclusions do not respond to the proposed objectives, they should be reformulated.

Author Response

Dear Reviewer,

Thank you for your review and the time taken to offer such constructive feedback. I have reviewed each point made and have made the following changes. I believe these changes to have strengthened the paper.

Abstract

They should revise the entire methodology section, as it is not clear what type of study was carried out and where the participants came from.

Regarding the methodology, it is not clear what was carried out, the abstract was written for those who are familiar with the subject, not for those who are learning about it and reading it for the first time. The results lack the data needed to draw a conclusion. Nor does the conclusion respond to the proposed objectives.

The keywords should not be the same as those already in the title, please change them.

Please find below, the responses to these points.

• The method section was modified to include the design of the study and where the participants came from
• I have tried to re-write the method to help those reading it for the first time understand what took place. The results and conclusions have been amended to be more inline with the study aims. I am limited, however to how much additional information I can include given the 250-word limit (see lines 9 to 29).
• The key words have been modified, so that they are different to those used in the title (see line 30).

Introduction

The introduction does not justify the relevance of developing the study in question, and is very poor in its justification.

• I have reworded the introduction to emphasise the relevance of the study (see lines 37-54).

The objectives proposed in the introduction are not in line with those described in the abstract.

• The aims and objectives are now more aligned with the abstract and discussion (see lines 55-63).

Materials and Methods 

We need to know which institution submitted the study, which ethics committee approved it and the registration number of the ethics committee's report.

• Institutional data and ethics committee reference number are included (see lines 67-68)

The entire methodology needs to be reviewed and reformulated, since it is not clear what has been done, even in terms of the questionnaires to be filled in.

• I have reviewed the procedural information for clarity, and have made changes that will hopefully make this section clearer.

Results

The results as presented are very confusing.

• I have reviewed the results to make it clearer

Why there is no characterisation of the participants, several of their characteristics may help to explain the results found.

• The method section contains participant characteristics (see lines 65-72). However, some additional information on the participants based on questionnaire scores (see lines 158-164)

They must standardise the decimal places in the different tables.

• The data are different and therefore a consistent number of decimal places would not be possible. Where they are similar variables (i.e. sway path lengths), these are in a consistent format.

The different tables lack legends for the different acronyms used.

• The tables now contain legends as requested (see line 198)

Table 2 is not referenced in the text in the results section.

• Table 2 is now referenced in text (see line 208)

Discussion 

In this section you should discuss these questions: (1) How does prolonged activity affect postural control in older adults; (2) What evidence suggests that the plantar flexor muscles were fatigued; (3) What factors might explain the individual differences in postural control responses to prolonged activity; (4) How could future research improve upon the methods used in this study to better assess fatigue effects on postural control.

Responses can be seen via:

• See lines 235-239
• See line 235
• See lines 284-289
• See lines 299-311                                               

Conclusions 

The conclusions do not respond to the proposed objectives, they should be reformulated.

• Conclusions are now aligned with the aims.

Reviewer 2 Report

Comments and Suggestions for Authors

Overall –

 

Not bad at all. Below are some observations/comments intended to help refine the manuscript in a positive manner. 

 

Some sentences are overly complex or awkwardly structured, making them difficult to read. Consider breaking long sentences into two or restructuring for better flow.  

 

Certain words or phrases could be more precise or natural to enhance readability.  

 

Some sections contain verb tense inconsistencies. Ensure past or present tense is used consistently throughout.  

 

Some instances where definite or indefinite articles should be used for clarity.  

 

A few spelling and typographical errors need correction.  

 

Title:  

Exploring the effect prolonged ankle plantarflexed standing on postural control, balance confidence, falls efficacy and perceived balance in older adults.  

 

Suggestion: 

Exploring the Effect of Prolonged Ankle Plantarflexed Standing on Postural Control, Balance Confidence, Falls Efficacy, and Perceived Balance in Older Adults. 

 

Abstract:  

Following these trials, participants then stood with ankles plantarflexed for up to 7.5 minutes, before collecting another force plate quiet standing trial.  

 

Suggestion: 

Following these trials, participants stood with their ankles in a plantarflexed position for up to 7.5 minutes before completing another quiet standing trial on the force plate. 

 

Mean values for the 5 trials at each time point were calculate for each postural control variable... 

 

Suggestion:  

Mean values for the five trials at each time point were calculated for each postural control variable...

 

Changes in postural control occurred without a change in balance confidence or falls efficacy suggesting that the change in balance may not be practically significant or perceptible to the individual; this information is often missing in similar research.  

 

Suggestion:   

Changes in postural control occurred without a change in balance confidence or fall efficacy, suggesting that the change in balance may not be practically significant or perceptible to the individual. This information is often missing in similar research.  

 

Introduction:  

This section should be expanded. The information offered does not 'paint' a clear enough picture of what is of interest and why it is interesting. Specific suggestions follow: 

 

Older adults who undertake prolonged activity of the ankle plantar flexors can experience muscular fatigue, leading to greater postural sway area and sway path [3], indicative of an increased falls risk [4-5].  

 

Suggestion: 

Older adults who engage in prolonged activity involving the ankle plantar flexors may experience muscular fatigue, leading to increased postural sway area and sway path [3], which is indicative of a greater risk of falling [4-5]. 

 

Previous studies of older adult PC taken after prolonged activity have not explored control strategy change nor do they offer interpretation of their findings in relation to the data’s absolute and relative reliability, both of which can impact the conclusions drawn.  

 

Suggestion: 

Previous studies on postural control in older adults following prolonged activity have not explored changes in control strategy, nor have they provided interpretations of their findings in relation to the data’s absolute and relative reliability, both of which can impact conclusions.

 

Materials and Methods: 

Overall - well done. Specific suggestions follow: 

Participants signed informed consent forms, confirming that they were understood the nature of the study and were happy to participate.  

 

Suggestion: 

Participants signed informed consent forms, confirming that they understood the nature of the study and agreed to participate.  

 

PF standing was then repeated a further 4 times, each lasting 2minutes; quiet standing data was again recorded after each.   

 

Suggestion: 

Plantarflexed standing was then repeated four more times, each lasting two minutes; quiet standing data was recorded after each session.

 

Results:  

I found this section to be adequate. Specific suggestions follow:

All participants performed 5 PF standing trials although 7 participants could not sustain the maximum protocol duration (7.5minute duration) for trial 1; all completed the PF standing trials 2 – 4 (2minute durations).  

 

Suggestion:  

All participants performed five plantarflexed standing trials, although seven participants could not sustain the full 7.5minute duration for the first trial. However, all participants completed trials two through four, each lasting two minutes.

 

Prolonged standing resulted in in significantly greater AP (t (23) = 3.39, p = 0.003, d = 0.54) and total sway path length...  

 

Suggestion: 

Prolonged standing resulted in significantly greater AP (t(23) = 3.39, p = 0.003, d = 0.54) and total sway path length...

 

Discussion:  

I found this section to be the most robust. Please avoid repeating transitional words, despite is used to begin a few paragraphs. Shift that term. Other specific suggestions follow:

 

This study explored the effect on prolonged activity on PC.  

 

Suggestion: 

This study explored the effect of prolonged activity on postural control. 

 

Group change may have also been influenced by noise within the data, affecting the data reliability. 

 

Suggestion: 

Group differences may have also been influenced by variability in the data, affecting its reliability.

 

The document is well structured and contains valuable research, but improving grammar and syntax will enhance its readability. All of which are small changes that can be completed in short order. 

 

 

Author Response

Dear Reviewer,

Thank you for your review and the time taken to offer such constructive feedback. I have reviewed each point made and have made the following changes. I believe these changes to have strengthened the paper.

 

Some sentences are overly complex or awkwardly structured, making them difficult to read. Consider breaking long sentences into two or restructuring for better flow.  

 

Certain words or phrases could be more precise or natural to enhance readability.  

 

Some sections contain verb tense inconsistencies. Ensure past or present tense is used consistently throughout.  

 

Some instances where definite or indefinite articles should be used for clarity.  

 

A few spelling and typographical errors need correction.  

 

• Thank you I have gone through and revised the paper based on these points

 

Title

• The suggested change reads better, thank you

Abstract

Suggestion: Following these trials, participants stood with their ankles in a plantarflexed position for up to 7.5 minutes before completing another quiet standing trial on the force plate.

• Change accepted (see line 16-18)

Mean values for the five trials at each time point were calculated for each postural control variable...

• Change accepted (see line 22)   

Changes in postural control occurred without a change in balance confidence or fall efficacy, suggesting that the change in balance may not be practically significant or perceptible to the individual. This information is often missing in similar research.  

• Change accepted (see lines 27-29) 

Introduction

This section should be expanded. The information offered does not 'paint' a clear enough picture of what is of interest and why it is interesting. Specific suggestions follow: 

• I have placed greater emphasis on the need for the study and why it is of interest (see lines 37-54)

Older adults who engage in prolonged activity involving the ankle plantar flexors may experience muscular fatigue, leading to increased postural sway area and sway path [3], which is indicative of a greater risk of falling [4-5]. 

• Change accepted (see lines 33-36)

Previous studies on postural control in older adults following prolonged activity have not explored changes in control strategy, nor have they provided interpretations of their findings in relation to the data’s absolute and relative reliability, both of which can impact conclusions.

• Change accepted (see lines 40- 48) – please note that this is incorporated with another reviewer’s comments.

Materials and methods

• Thank you for the suggested changes please see changes below

Participants signed informed consent forms, confirming that they understood the nature of the study and agreed to participate. 

• Change accepted (see lines 74-76) – please note that this is incorporated with another reviewer’s comments.

Plantarflexed standing was then repeated four more times, each lasting two minutes; quiet standing data was recorded after each session.

• Change accepted (see lines 88 – 90) – please note that this is incorporated with another reviewer’s comments.

Results

• Thank you for the suggested changes

All participants performed five plantarflexed standing trials, although seven participants could not sustain the full 7.5minute duration for the first trial. However, all participants completed trials two through four, each lasting two minutes.

• Change accepted (see lines 162-164)

Prolonged standing resulted in significantly greater AP (t(23) = 3.39, p = 0.003, d = 0.54) and total sway path length...

• Change accepted (see line 165)

Discussion

I found this section to be the most robust. Please avoid repeating transitional words, despite is used to begin a few paragraphs. Shift that term.

• Transitional words have been revised.

This study explored the effect of prolonged activity on postural control. 

• Change accepted (see line 227)

Group differences may have also been influenced by variability in the data, affecting its reliability.

• Change accepted (see line 271)

The document is well structured and contains valuable research, but improving grammar and syntax will enhance its readability. All of which are small changes that can be completed in short order. 

• Thank you. I have reviewed this carefully.

Reviewer 3 Report

Comments and Suggestions for Authors

The author must be commended for the concise write up, yet the methodology lacks sufficient detail, leading to the veracity of the results being questionable. Simple citations to other papers about methodology are not adequate. A quick description or summary is warranted. Novel aspects like how fractal dimensions were calculated are required. 

There are far too many acronyms used in this manuscript, which is confusing for the reader. Df is usually synonymous with degrees of freedom. Please use standardized terms used in biomechanics. Non standardized terms should be spelled out.

• Rodgers MM, Cavanagh PR. Glossary of biomechanical terms, concepts, and units. Phys Ther. 1984 Dec;64(12):1886-902. doi: 10.1093/ptj/64.12.1886. PMID: 6505033.

 

Material and Methods

• Twenty-four healthy community living older adults (73.7 ± 6.8 years; Male/Female = 52 9/15) volunteered for this study.
• Describe the sites or locations where research was conducted.
• Describe methods used to identify and recruit study participants. Sample and sampling method including why this sample was chosen I,e, Random selection, combined convenience and snowball sampling.
• Describe whether medical record reviews were undertaken, or other clinical information used to identify and clear potential subjects.
• Identify Exclusion Criteria
  • Impact of Diabetic Complications is a disqualifier, which is known to impact balance due to complications like peripheral neuropathy, vestibular dysfunction, and vision loss thus impairing balance and increased risk of fall.
    • D'Silva LJ, Lin J, Staecker H, Whitney SL, Kluding PM. Impact of Diabetic Complications on Balance and Falls: Contribution of the Vestibular System. Phys Ther. 2016 Mar;96(3):400-9. doi: 10.2522/ptj.20140604. Epub 2015 Aug 6. PMID: 26251477; PMCID: PMC4774386
  • Large-joint issues: Pain and disability.
  • Body mass index (BMI) is correlated with balance, with higher BMI linked to poorer balance. This is because excess weight can impact postural stability
• Further elucidate the a-priori sample size determination of 24 participants based on statistical power of 0.8 with p = 0.05, and d = 0.75. Which postural control variable was used is not specified. Specify how means differences between two dependent means (matched pairs) was determined, whether from pilot data of identified from the literature (citation required).
• Baseline sway measure, PF trial, then 5 repeated 20s sway measurements interspersed between 2 min PF interventions.
• Specify what software was used to compute linear measurements (A-P), (M-L) and total sway path length and A-P and M-L RMS and RMS radius. Sway area (95% confidence ellipse) was also determined. Whether proprietary Kistler Bioware software or data imported into MatLab or other software and metrics derived offline is not specified.
• Postural stability and fractal dynamics [16]. Only the reference was cited in how fractal dimensions were calculated over the 20s baseline and PF intervals. Notable, were averages derived over the 5 baseline trials and similarly the 5 post baseline intervals? Why? Would not the pre and last trial be more relevant? Please substantiate.

All data analysis was conducted using SPSS (IBM SPSS Statistics, version 25).  Missing data was omitted from calculations and reflected in the overall count of responses.  Statistical significance was accepted at p<.05.

FE (Falls Efficacy Scale, FES-I) [17]. Likert Scale Ranked ordinal data

The FES-I questionnaire consists of 16 questions on functional activities, which is used to assess the fear of falling issue among older adults.  The shortened version of the FES-I scale contains 7 items originating from the original FES-I questionnaire, allowing for a faster survey among the elderly individuals. The FES-I, as opposed to the Short FES-I is recommended for clinicians and researchers interested in all 16 activities accounted for on the scale. Specify which version was used. Notably, the reference for validating the FES-I and short FES-I scales was for the Polish Falls Efficacy Scale, which is inappropriate for this study.

Review the following, summarize, and report psychometric properties.

1. Greenberg, S. A. (2012). Analysis of measurement tools of fear of falling among high-risk, community-dwelling older adults. Clinical Nursing Research, 21(1), 113-130. https://doi.org/10.1177/1054773811433824.
2. Greenberg, S. A., Sullivan-Marx, E., Sommers, M. S., Chittams, J., & Cacchione, P. Z. (2016). Measuring fear of falling among high-risk, urban, community-dwelling older adults. Geriatric Nursing, 37(6), 489-495. https://doi.org/10.1016/j.gerinurse.2016.08.018.
3. Hauer, K.A., Kempen, G.I., Schwenk, M., Yardley, L., Beyer, N., Todd, C., Oster, P., & Zijlstra, G.A. (2011). Validity and sensitivity to change of the Falls Efficacy Scales International to assess fear of falling in older adults with and without cognitive impairment. Gerontology, 57(5), 462-472. https://doi.org/10.1159/000320054.
4. Kempen,G.I., Todd, C.J., Van Haastregt, J.C., Zijlstra, G.A., Beyer, N., Freiberger, E., Hauer, K.A., Piot-Ziegler, C.,& Yardley, L. (2007). Cross-cultural validation of the Falls Efficacy Scale International (FES-I) in older people: Results from Germany, the Netherlands and the UK were satisfactory. Disability and Rehabilitation, 29(2), 155-162. https://doi.org/10.1080/09638280600747637.
5. Kempen, G. I., Yardley, L., van Haastregt, J. C., Zijlstra, G. A., Beyer, N., Hauer, K., & Todd, C. (2008). The Short FES-I: A shortened version of the Falls Efficacy Scale-International to assess fear of falling. Age and Ageing, 37(1), 45-50. https://doi.org/10.1093/ageing/afm157.
6. Tinetti, M.E., Mendes de Leon, C.F., Doucette, J.T., & Baker, D.I. (1994). Fear of falling and fall-related efficacy in relationship to functioning among community-living elders. Journal of Gerontology: Medical Sciences, 49(3), M140-M147. https://doi.org/10.1093/geronj/49.3.m140.
7. Tinetti, M.E., Richman, D., & Powell, L. (1990). Falls efficacy as a measure of fear of falling. Journal of Gerontology, 45(6), P239-P243 https://doi.org/10.1093/geronj/45.6.p239.
8. Yardley, L., Beyer, N., Hauer, K., Kempen, G., Piot-Ziegler, C., & Todd, C. (2005). Development and initial validation of the Falls Efficacy Scale-International (FES-I). Age and Ageing, 34(6), 614-619. https://doi.org/10.1093/ageing/afi196.

Overall summary of internal reliability and test retest reliability

• Sherry A. Greenberg. Assessment of Fear of Falling in Older Adults: The Falls Efficacy Scale-International (FES-I). The Hartford Institute for Geriatric Nursing, New York University, Rory Meyers College of Nursing is cited as the source. https://hign.org/sites/default/files/2022-11/FES-I.pdf.

Balance confidence was assessed with the Activities-specific Balance Confidence (ABC) Scale [9].   Outcome scores are ordinal (ranked) data

< 50 indicated a low level of physical functioning

≥ 50 < 80 indicated a moderate level of functioning

≥ 80 are indicative of highly functioning,

 

15-point Generalised Rating of Change (GRC) question [17] modified

• The self-report GRC is a single-item, recall-based questionnaire of global well-being and pain since an initial treatment encounter.
• Patients make global ratings on changes in balance since the baseline examination on a 15-point self-report Likert scale (from −7 to 7). Degree and importance ratings of change are summed for a range of 1 to 14 for improvement, 0 for no change, or −1 to −14 for deterioration.
• Outcome scores are ordinal (ranked) data
• This global rating format has been used previously to provide an external standard for change in functional status. Report moderate psychometric properties when used in the short term.
  • Paul W Stratford, Jill M Binkley, Daniel L Riddle, Health Status Measures: Strategies and Analytic Methods for Assessing Change Scores, Physical Therapy, Volume 76, Issue 10, 1 October 1996, Pages 1109–1123, https://doi.org/10.1093/ptj/76.10.1109
  • John Schmitt, Richard P. Di Fabio. The Validity of Prospective and Retrospective Global Change Criterion Measures. Archives of Physical Medicine and Rehabilitation, 86(12), 2005, Pages 2270-2276. https://doi.org/10.1016/j.apmr.2005.07.290.

Ordinal data is less precise than interval data because it doesn't indicate the degree of variation between data points.

To score pre-post ordinal data, typically you would calculate the difference between the post-test score and the pre-test score for each individual, essentially creating a new variable representing the "change" in their ranking on the ordinal scale; this is commonly referred to as a "gain score" and is a simple way to analyze whether there was an overall improvement or decline in the measured variable across the pre and post conditions.

Associations between the change in PC (continuous) data and change in BC and FE (ranked ordinal data) should not be deriver using Pearson’s Correlation Coefficients. Pearson (r) are suited for continuous data. Rather the following are likely more appropriate:

• Point biserial correlations (r_pb) reported for dichotomous/continuous associations,
• Phi coefficients (ϕ) reported for dichotomous/dichotomous associations,
• Kendall (T) and Spearman (rs) for ordinal (ranked) data.

Author Response

Dear Reviewer,

Thank you for your review and the time taken to offer such constructive feedback. I have reviewed each point made and have made the following changes. I believe these changes to have strengthened the paper.

The author must be commended for the concise write up, yet the methodology lacks sufficient detail, leading to the veracity of the results being questionable. Simple citations to other papers about methodology are not adequate. A quick description or summary is warranted. Novel aspects like how fractal dimensions were calculated are required.

• Thank you and the fractal dimension equation has now been added (see line 103).

There are far too many acronyms used in this manuscript, which is confusing for the reader. Df is usually synonymous with degrees of freedom. Please use standardized terms used in biomechanics. Non standardized terms should be spelled out.

• Thank you this has been reviewed throughout. To note Df is the typical abbreviation of fractal dimension, although I agree it is easier to follow when written out.

Material and Methods

Describe the sites or locations where research was conducted.

• Information has been included (see lines 67 – 68)

Describe methods used to identify and recruit study participants. Sample and sampling method including why this sample was chosen I,e, Random selection, combined convenience and snowball sampling.

• Information has been included (see line 71)

Describe whether medical record reviews were undertaken, or other clinical information used to identify and clear potential subjects.

• Medical records were not checked

Identify Exclusion Criteria

• These have been added (see lines 69-72)

Impact of Diabetic Complications is a disqualifier, which is known to impact balance due to complications like peripheral neuropathy, vestibular dysfunction, and vision loss thus impairing balance and increased risk of fall.

• No participant reported these issues and was part of the exclusion criteria (see line 66-72)

Large-joint issues: Pain and disability.

• No participant reported these issues and was part of the exclusion criteria (see line 66-72)

Body mass index (BMI) is correlated with balance, with higher BMI linked to poorer balance. This is because excess weight can impact postural stability

• This is added to the discussion. However, given this is a within subject design study there is limited evidence that this would directly impact the effect of prolonged standing.

Further elucidate the a-priori sample size determination of 24 participants based on statistical power of 0.8 with p = 0.05, and d = 0.75. Which postural control variable was used is not specified. Specify how means differences between two dependent means (matched pairs) was determined, whether from pilot data of identified from the literature (citation required).

• Apriori sample size was calculated on a large effect size, deemed by the researcher as appropriate given this would be needed for a change in the subjective data; this was described in the paper (see line 72-75).

Baseline sway measure, PF trial, then 5 repeated 20s sway measurements interspersed between 2 min PF interventions.

• Changes to the sentence regarding baseline sway measures were made (see line 83-84).

Specify what software was used to compute linear measurements (A-P), (M-L) and total sway path length and A-P and M-L RMS and RMS radius. Sway area (95% confidence ellipse) was also determined. Whether proprietary Kistler Bioware software or data imported into MatLab or other software and metrics derived offline is not specified.

• Information on the software used to calculate the variables is now included (see line 99-102)

Postural stability and fractal dynamics [16]. Only the reference was cited in how fractal dimensions were calculated over the 20s baseline and PF intervals. Notable, were averages derived over the 5 baseline trials and similarly the 5 post baseline intervals? Why? Would not the pre and last trial be more relevant? Please substantiate.

• The average of 5 trials were used since this improves the reliability. The first and last trials would include too much variability to use alone. A comment has been added on reliability (see line 131-133)

All data analysis was conducted using SPSS (IBM SPSS Statistics, version 25).  Missing data was omitted from calculations and reflected in the overall count of responses.  Statistical significance was accepted at p<.05.

• Comment on omitted data is now added (see line 141-143)

FE (Falls Efficacy Scale, FES-I) [17]. Likert Scale Ranked ordinal data

The FES-I questionnaire consists of 16 questions on functional activities, which is used to assess the fear of falling issue among older adults.  The shortened version of the FES-I scale contains 7 items originating from the original FES-I questionnaire, allowing for a faster survey among the elderly individuals. The FES-I, as opposed to the Short FES-I is recommended for clinicians and researchers interested in all 16 activities accounted for on the scale. Specify which version was used. Notably, the reference for validating the FES-I and short FES-I scales was for the Polish Falls Efficacy Scale, which is inappropriate for this study.

Review the following, summarize, and report psychometric properties.

Thank you a review of the literature was undertaken. Your guidance here was very much appreciated.

• Content added on FES-1 (see lines 106-113)
• Content added on ABC (see lines 113-119)
• Content added on GRC (see lines 120-129)

To score pre-post ordinal data, typically you would calculate the difference between the post-test score and the pre-test score for each individual, essentially creating a new variable representing the "change" in their ranking on the ordinal scale; this is commonly referred to as a "gain score" and is a simple way to analyze whether there was an overall improvement or decline in the measured variable across the pre and post conditions.

• Gain score is now mentioned (see line 136)

Associations between the change in PC (continuous) data and change in BC and FE (ranked ordinal data) should not be deriver using Pearson’s Correlation Coefficients. Pearson (r) are suited for continuous data. Rather the following are likely more appropriate:

• Difference and correlations have been re-evaluated using a Wilcoxon and Spearman’s rank correlation respectively (See lines 134, 136).

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Thank you for the opportunity to review this paper again.

The changes that were suggested and made have greatly improved the paper.

However, in the discussion section, I think we still need to discuss more and understand these two points better: (1) How does prolonged activity affect postural control in older adults; (2) What evidence suggests that the plantar flexor muscles were fatigued; 

Author Response

Dear Reviewer,

Thank you very much for your comment:

However, in the discussion section, I think we still need to discuss more and understand these two points better: (1) How does prolonged activity affect postural control in older adults; (2) What evidence suggests that the plantar flexor muscles were fatigued; 

I believe that I have now provided detail on this within the manuscript (please see lines 234 - 251).

Best wishes.

Reviewer 3 Report

Comments and Suggestions for Authors

In general, I think the manuscript is interesting in exploring prolonged standing ankle plantar-flexion on postural control, balance confidence, falls efficacy, and perceived balance in older adults.  The author has satisfactorily incorporated many of the required changes and the current revision is well written and coherent.

Yet, my concern on subject recruitment remain, which I think warrents futher elaboration. See below as example. 

A convenient sample of 24 older adults (73.7 ± 6.8 years; Male/Female = 9/15) meeting the inclusion and exclusion criteria were recruited from a well-established independent senior living facility in the [location] area. Inclusion criteria include older adults be (1) at least 60 years old and (2) could independently walk without an assistant device (e.g., cane and walkers).  Older adult residents with cognitive impairment, deteriorated musculoskeletal or neurological function, and any medical disease history that impair walking and balance (e.g., arthritis, diabetes, visuospatial deficits) were excluded.   

Otherwise, there are comments listed as track change on the document that need to be adddressed. 

Author Response

Dear Reviewer, thank you for the suggestion provided:

A convenient sample of 24 older adults (73.7 ± 6.8 years; Male/Female = 9/15) meeting the inclusion and exclusion criteria were recruited from a well-established independent senior living facility in the [location] area. Inclusion criteria include older adults be (1) at least 60 years old and (2) could independently walk without an assistant device (e.g., cane and walkers).  Older adult residents with cognitive impairment, deteriorated musculoskeletal or neurological function, and any medical disease history that impair walking and balance (e.g., arthritis, diabetes, visuospatial deficits) were excluded.   

This has been incorporated where relevant into the text (please see Lines 65-71) and track changes have now been removed. 

Best wishes

Dan