Review Reports - Gait Symmetry Is Unaffected When Completing a Motor Dexterity Task While Using a Walking Workstation in Healthy, Young Adults

Round 1

Reviewer 1 Report

Review comment

This manuscript entitled “Gait symmetry is unaffected when completing a motor dexterity task while using a walking workstation in healthy, young adults” primarily aimed to examine lower extremity gait symmetry while completing a fine motor dexterity task, and to quantify and compare fine motor hand dexterity task performance while using a walking workstation compared to baseline. The authors bring an interesting study, but there are still some problems that cannot up this study to a publishing level. Some suggestions are listed in the specific comments below.

Specific comments:

1. Line 10, the description of the study background is too wordy, please simplify it further. In addition, the authors should emphasize the purpose of this study in the abstract section.

2. Line 20, ‘Using a walking workstation did not affect gait function in healthy, young adults…’ ‘walking workstation use may decrease hand dexterity, and potentially work performance’, these conclusions are not rigorous and more evidence needs to be provided to support them.

3. Line 25, Please modify and improve the quality of the keywords as this will assist others when they are searching for information on your research topic. Avoid using ‘Gait symmetry’ and ‘Walking Workstation’ since they appear in the title.

4. Line 65, It is definitely of general interest to understand better the influence of dual-task conditions on gait parameters. But more than this, it is not clear the reason why gait symmetry was chosen here to investigate its association with the motor dexterity task. Please further emphasize the significance and potential value of this study.

5. Line 103, I suggest that the authors could add a figure to give the readers a better understanding of the procedures in this study.

6. Line 152, ‘Symmetry of bilateral lower extremity angular joint positions (hip, knee, and ankle), and stride length were used for analysis.’, more details need to be provided to illustrate the parameters included in this study and the processing methods.

7. In summary, please ensure that your manuscript is prepared correctly and formatted before submitting a revision.

Author Response

We thank the reviewer for the suggestions.

Specific comments:

Line 10, the description of the study background is too wordy, please simplify it further. In addition, the authors should emphasize the purpose of this study in the abstract section.

The background has been simplified in the document on line 10. We have also added the purpose of the study to the abstract in lines 11-13.

Line 20, ‘Using a walking workstation did not affect gait function in healthy, young adults…’ ‘walking workstation use may decrease hand dexterity, and potentially work performance’, these conclusions are not rigorous and more evidence needs to be provided to support them.

The conclusions have been revised to be more rigorous by citing the outcomes revealed by the study in line 21-23.

Line 25, Please modify and improve the quality of the keywords as this will assist others when they are searching for information on your research topic. Avoid using ‘Gait symmetry’ and ‘Walking Workstation’ since they appear in the title.

The keywords have been updated; ‘Gait symmetry’ and ‘walking workstation’ have been removed and replaced with ‘Purdue Pegboard Test’ and ‘gait function’.

Line 65, It is definitely of general interest to understand better the influence of dual-task conditions on gait parameters. But more than this, it is not clear the reason why gait symmetry was chosen here to investigate its association with the motor dexterity task.Please further emphasize the significance and potential value of this study.

Further clarification has been added to line 87.

Line 103,I suggest that the authors could add a figure to give the readers a better understanding of the procedures in this study.

We have included images of the pegboard and the walking workstation after lines 128 and 156, respectively.

Line 152, ‘Symmetry of bilateral lower extremity angular joint positions (hip, knee, and ankle), and stride length were used for analysis.’, more details need to be provided to illustrate the parameters included in this study and the processing methods.

The angular joint position details, now on line 168, have been updated for clarification.

In summary, please ensure that your manuscript is prepared correctly and formatted before submitting a revision

The authors appreciate this comment, however, we have followed the MDPI biomechanics template and author guidelines to ensure the manuscript is prepared and formatted correctly.

Reviewer 2 Report

Dear Authors, the comments are attached.

Comments for author File: Comments.pdf

Author Response

Introduction: Line 31, 35 - please insert spaces after workers, and after numbers (linie 35).

Authors have included these spaces.

In line 90 the sharing model is mentioned, it is previously mentioned in line 39. Please describe it better in the introduction if a hypothesis is drawn based on this model.

Authors have added further clarification of the sharing model in line 98.

Material and Methods

-Participants section - Did you check how people walk on the treadmill before the survey? Or was just a verbal declaration enough?

Participants were asked to walk on a treadmill prior to data collection in order to determine their comfortable gait speed, however we did not examine treadmill walking prior to testing.

-Procedures - Did you save the results from the sitting and standing positions of the test?

Yes, the results from the sitting and standing positions of the test were saved. They were also included in analysis where we revealed that sitting and standing positions were not significantly different. The only significant difference among the conditions was during walking. PPT scores are reported in lines 215-224 and in figure 4.

Please include a picture of the Purdue Pegboard Test in this section. I had to see what it was about on the Internet, because I was not familiar with this test. I suppose many readers may not know it.

An image of the PPT was included in the manuscript.

I understand that data was collected only from the lower limbs? Again, please post photo of participant on the treadmill and Workstation desk.

Correct, the data was only collected from the lower limbs; an image of the workstation and markers was added for ease of understanding.

Why was one of the Vicon protocols not used?

The marker set we used was part of a larger dataset that required a more precise set of markers than one of the Vicon protocols could provide. The Vicon Plug-in-Gait model is only sufficient for sagittal plane motion analysis, however, the cluster marker set provides more accurate and representative data in the frontal and transverse planes.

-Line 144 – which number of Nexus?

Nexus v2.9.1; see addition to the manuscript on line 162.

-Line 150 – 159 - Did Xr and Xl represent trajectories of angles in the gait cycle domain? So, did SI represent a trajectory? Why did you subtract from Xr - Xl and not vice versa? What did you do when there was a negative value? This disturbs the veracity of the average count in the next section. The absolute value should be counted to avoid error.

As described in the manuscript, we utilized the symmetry index ratio proposed by Robinson and colleagues, which has been utilized throughout the gait literature since it was published in 1987, as referenced in the Błażkiewicz (2014) paper you recommended below. However, the authors understand how negative outcomes from this method can alter mean values, as such, we have recomputed all SI values and reported the absolute SI value to remove any confusion. We have included this in-text, as well. Additionally, we have included baseline and DT mean and standard deviation values in Table 1 for easier comparison between the conditions. This was omitted in the initial version.

-Line 158 – 159 – please, provide the intervals for each sub-phase.

The authors have added clarification of the sub-phase percentages to lines 178-180.

Results

-It is assumed that p-values should have 4 decimal places, please correct throughout the text.

The authors have updated the p-values to have 4 significant digits and 3 decimal places.

-Figure 1 is of poor quality and I am unable to read what the stride length was. Please add the means and standard deviations above the bars.

Please see the newly revised Fig 1.

-I do not understand Table 1.

Please see the newly revised Table 1.

-I see negative values in the table, which makes my assumption from the earlier section correct. Please recalculate the symmetry index again so that there are no negative values using the absolute value or by subtracting the smaller number in the numerator from the larger number.

The Table has been updated in the manuscript with corrections.

-Additionally, if these are ANOVA results, the table should look different. Let me not continue to read the work, because if my assumptions are good, then the discussion is bad.

Table 1 is not an ANOVA table because dependent t-tests were used as statistical tests.

-In conclusion, I ask you to recalculate the indexes again and correct the work. Please look at the paper: Błażkiewicz M., Wiszomirska I., Wit A. (2014) Comparison of four methods of calculating the symmetry of spatial-temporal parameters of gait. Acta of Bioengineering and Biomechanics 16 (1)

The authors appreciate the text recommendation and have corrected the work.

Reviewer 3 Report

Main comments

The article aimed to verify the influence of using a workstation combined with a dual task during gait on dexterity and lateral gait symmetry. Symmetry was not modified with the addition of the warkstation to the dual-task condition but dexterity was reduced. The strengths of the study are i) that the study is well written and organized; ii) the biomechanical methods and equipment are well used. My central criticism is the lack of overall biomechanical results (space-time (length, stride frequency, contact time and swing), and description of mean +- dp values of the angular results. Another central criticism is the lack of results in the no dual task condition. I also suggest to insert a figure showing the setup of the workstation and it would be very nice to see a video as supplementary material showing the conditions. Consider including the speeds chosen in results.

Minor points

Line 146 – consider including the order of filter used.

I think you used the lower limb model of plug-in-gait of Vicon. Inform.

I suggest replacing the bar graph in figures 1, 2 with combining dot plots with box or violin plots

Also, consider including the real mean values +- dp in table 1 of every condition.

Looking closely at the figure, I notice that the stride length values decreased in the dual task and the variability increased. It would be interesting to see if interstride variability increased, and, of course, to compare stride length and frequency.

Author Response

Main comments

The authors appreciate the concern; however, we disagree on the lack of biomechanical results. Gait function, which was measured as gait symmetry of the lower extremity angular joint positions, is a direct examination of the angular space each lower extremity joint pairing moved. Additionally, we quantified stride length symmetry, which is also a direct examination of space. Furthermore, we examined gait sub-phases which are temporally split for various actions during the gait cycle. To the reviewer’s point, specifically quantifying length, stride frequency, contact time, etc. was not performed in this study, we examined derivatives of many biomechanical variables including stride length, and angular joint positions.

And description of mean +- dp values of the angular results.

The table for angular results has been updated

Another central criticism is the lack of results in the no dual task condition.

The authors would like to refer the reviewer to the updated Table 1, which displays dual task symmetry magnitudes. This information was omitted in error on the initial submission.

I also suggest to insert a figure showing the setup of the workstation and it would be very nice to see a video as supplementary material showing the conditions. Consider including the speeds chosen in results.

Please see the figure of the set up within the manuscript after line 156. The authors excluded speed comparisons due to the speeds being chosen by participants remaining constant between all conditions and the within-subjects design. Had this study used a between-subjects design, differing speeds would need to have been controlled for to ensure outcomes were not confounded.

Minor points

Line 146 – consider including the order of filter used.

Please see the highlighted section on line 168.

I think you used the lower limb model of plug-in-gait of Vicon. Inform.

The authors used an adaptation to the lower limb model from Vicon, however it is not plug-in-gait; the model used includes marker clusters rather than single lateral markers to allow assessment of frontal and transverse plane motion more accurately, should we choose to analyze these planes.

I suggest replacing the bar graph in figures 1, 2 with combining dot plots with box or violin plots

The authors chose to use bar graphs to show symmetry between the limbs rather than distribution of the data that may be represented by a box or violin plots. Additionally, understanding individual participant outcomes is outside of the scope of this project as we were only concerned with gait symmetry on this relative population.

Also, consider including the real mean values +- dp in table 1 of every condition.

Table 1 has been updated.

The authors appreciate this comment, however, variability and interstride metrics are outside of the scope of this symmetry analysis. Additionally, the stride length values did decrease slightly, but without statistical significance.

Round 2

Reviewer 2 Report

Dear Authors, thank you for improving your paper. All my comments have been taken into account and I have no further comments.