Preliminary Evidence That Design Fluency Is Related to Dual-Task Treadmill Gait Variability in Healthy Adults

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript expored the relationship between inhibition, reasoning, fluency, and variability in stride length and step width during dual task treadmill walking in a sample of 19 healthy adults. Three experimental conditions were assessed. Results evidenced that processing speed was reduced, step width increased, and stride length decreased while dual tasking. However, variability in gait parameters was not modified consistently with a gait/posture first approach. Higher performance on a visual design fluency task which represented cognitive flexibility was associated with lower dual task stride length and step width vatiability.

I found the manuscript interesting, nicely structured and described, appropriate for the Journal. I encourage the Authors to tackle my points listed below in a suitable revision before the paper can be considered for Publication by the Editors.

1. The Introduction should be improved. A more solid and coprehensive theoretical framework should be provided. A strong rationale for the current investigation should be justified. For example, the Authors quoted only one study as primarily relevant (i.e., van Iersel et al., 2008). I wonder whether further empirical contribuions are available and what has been done up to date on dual task. What this study adds to the existing literature? Clarification is needed.

2. Although a convenience sample was considered, I feel that the eligibility criteria (i.e., both including and excluding) for the recruited participants should be included and finely detailed.

3. n the discussion section, the implications of the findings for both research and clinical practice should be critically argued and relevant citations should be added. Currently, the Authors nicely discussed the results but the implications are lacking.

4. Future research perspectives, currently missing, should be included in a final section.

Author Response

We thank the reviewers for their time and effort in carefully reviewing our manuscript. We found their comments very helpful and believe that the changes they precipitated resulted in an improved manuscript. Our responses to their specific comments can be found below.

 

REVIEWER 1

 

1. The Introduction should be improved. A more solid and coprehensive theoretical framework should be provided. A strong rationale for the current investigation should be justified. For example, the Authors quoted only one study as primarily relevant (i.e., van Iersel et al., 2008). I wonder whether further empirical contribuions are available and what has been done up to date on dual task. What this study adds to the existing literature? Clarification is needed.

Additional background information was added to the Introduction to address these issues and more clearly guide the reader to the rationale for the study.

2. Although a convenience sample was considered, I feel that the eligibility criteria (i.e., both including and excluding) for the recruited participants should be included and finely detailed.

Additional details were added to the manuscript regarding eligibility criteria.

3. n the discussion section, the implications of the findings for both research and clinical practice should be critically argued and relevant citations should be added. Currently, the Authors nicely discussed the results but the implications are lacking.

Additional information regarding the implications of the results was added to the Discussion.

4. Future research perspectives, currently missing, should be included in a final section.

The section regarding suggestions regarding future research was elaborated.

Reviewer 2 Report

Comments and Suggestions for Authors

Thank you for the opportunity to review your paper.

 

I found it very interesting, but I had some major concerns.

 

Details are provided below.

 

As the authors mention in the introduction, many studies on dual-task have been reported in the past. I understand that the novelty of the authors' research lies in the focus on parietal lobe functions such as visuospatial cognition, in addition to traditional executive functions (frontal lobe functions). However, the circumstances that led the authors to this focus are abrupt and unclear. This is an important point of the study, so please explain it in detail.

 

Regarding participant characteristics.

The average age is 39.74 years old, and the standard deviation is 22.65.

Also, looking at the standard deviation of walking speed, there are some subjects with a walking speed equivalent to sarcopenia.

I believe that sampling bias cannot be denied in these cases.

 

Regarding statistical analysis.

The authors mention that they chose to calculate Pearson's correlation coefficient and paired t-test.

These are parametric tests.

For this reason, please provide the results of a normality test.

 

This relates to the results of the statistical analysis above, but is a matter of the assertion made by the authors in their discussion. It is difficult to make a statement based only on the results of the correlation coefficient and univariate analysis. It is necessary to increase the number of subjects and then present the results of the multivariate analysis. I am puzzled as to why these points were not mentioned as limitations of the study. I interpret this as meaning that this is a preliminary study.

 

That's all.

Author Response

We thank the reviewers for their time and effort in carefully reviewing our manuscript. We found their comments very helpful and believe that the changes they precipitated resulted in an improved manuscript. Our responses to their specific comments can be found below.

REVIEWER 2

 

As the authors mention in the introduction, many studies on dual-task have been reported in the past. I understand that the novelty of the authors' research lies in the focus on parietal lobe functions such as visuospatial cognition, in addition to traditional executive functions (frontal lobe functions). However, the circumstances that led the authors to this focus are abrupt and unclear. This is an important point of the study, so please explain it in detail.

This section of the Introduction was elaborated.

Regarding participant characteristics. The average age is 39.74 years old, and the standard deviation is 22.65. Also, looking at the standard deviation of walking speed, there are some subjects with a walking speed equivalent to sarcopenia. I believe that sampling bias cannot be denied in these cases.

Linked to the comment below regarding the preliminary nature of the study (with which we agree), the sample is certainly heterogeneous in terms of age. This point is noted in the paragraph addressing limitations in the Discussion, the second to last paragraph.

We believe that the walking speed of our participants was not abnormally slow, given the age range and older adults included. In a large sample of adults 65 and older, a walking speed of 0.6 – 1.0 m/s was considered an “intermediate” walking speed (vs. “slow” or “fast” walking speed; citation below). While six of the 19 participants in our sample were over 65 years of age, none had a walking speed less than 0.6 m/s. The slowest walking speed in the sample was 0.75 m/s in a 5’0” tall individual 69 years of age. The stringent exclusion criteria also speak to the relative health of the sample.

Studenski S, Perera S, Wallace D, Chandler JM, Duncan PW, Rooney E, Fox M, Guralnik JM. Physical performance measures in the clinical setting. J Am Geriatr Soc. 2003 Mar;51(3):314-22. doi: 10.1046/j.1532-5415.2003.51104.x. PMID: 12588574.

Regarding statistical analysis. The authors mention that they chose to calculate Pearson's correlation coefficient and paired t-test. These are parametric tests. For this reason, please provide the results of a normality test.

Results regarding tests of normality were added to the manuscripts. The distribution of three variables were found to deviate significantly from normal. Analyses involving these variables were repeated using non-parametric tests. The results of these analyses were consistent with the results from the parametric tests. This information was added to the manuscript.

This relates to the results of the statistical analysis above, but is a matter of the assertion made by the authors in their discussion. It is difficult to make a statement based only on the results of the correlation coefficient and univariate analysis. It is necessary to increase the number of subjects and then present the results of the multivariate analysis. I am puzzled as to why these points were not mentioned as limitations of the study. I interpret this as meaning that this is a preliminary study.

These points were added as limitations of the study and noted as directions for future research. We agree that the study is preliminary in nature and language was added to the Abstract and body of the manuscript to describe it as such.

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

I have read the revised draft.

 

Please correct the following

 

About the title

 

As with the abstract, the title should clearly state that this is a preliminary study.

This will help readers to understand better.

 

About statistical analysis

 

It is better to mention the following before presenting the results to avoid discrepancies.

 

First, confirm the normality of the subject's data. Then, if normality is confirmed, the parametric tests, paired t-test and Pearson's product-moment correlation coefficient, are selected. If normality is not confirmed, the Wilcoxon signed-rank test and Spearman's rank correlation coefficient are selected.

 

For Table 2, the authors choose the Wilcoxon signed-rank test, which is a nonparametric test. For this reason, it is preferable to present the numerical values as median and interquartile range instead of mean and standard deviation.

 

Uniform notation throughout the text

 

Singular and plural forms are intermixed. For example, "older adults" and "older adult". Please also check for any other typographical errors or omissions.

 

That is all.

Author Response

We thank Reviewer 2 for their time and effort in reviewing the updated draft. We believe that the changes outlined below fully address their comments.

1. As with the abstract, the title should clearly state that this is a preliminary study.

The title was changed to reflect the preliminary nature of the study.

2. It is better to mention the following before presenting the results to avoid discrepancies. First, confirm the normality of the subject's data. Then, if normality is confirmed, the parametric tests, paired t-test and Pearson's product-moment correlation coefficient, are selected. If normality is not confirmed, the Wilcoxon signed-rank test and Spearman's rank correlation coefficient are selected.

This information was added to the Statistical Analysis section, prior to the results.

3. For Table 2, the authors choose the Wilcoxon signed-rank test, which is a nonparametric test. For this reason, it is preferable to present the numerical values as median and interquartile range instead of mean and standard deviation.

In Table 2, the mean and standard deviation values were replaced with median and IQR values for variables that were not normally distributed.

4. Uniform notation throughout the text. Singular and plural forms are intermixed. For example, "older adults" and "older adult". Please also check for any other typographical errors or omissions.

The manuscript was checked for typographical errors and such errors were corrected. A few errors regarding the statistical analyses and their interpretation that were present in earlier versions of the manuscript were also corrected.