The Impact of Induced Acceleration Perturbations in Selected Phases of the Gait Cycle on Kinematic and Kinetic Parameters

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Report for applsci-2985991-peer-review-v1

Kajetan Ciunelis, Rafał Borkowski, Michalina Błażkiewicz

 

Overall, it is relevant and interesting to report the influence of treadmill perturbations on joint torques. The idea to use SPM for quantifying the statistical effects on the time series is really good and interesting.

 

There are major issues that make that I can only recommend a rejection: 

 

- The introduction provides no motivation or hypothesis other than that joint torques might not have been reported before for gait perturbations. Accordingly, this is an entirely descriptive study, which is simply insufficient for such an extensively studied action such as gait. 

 

- According to the methods, the perturbations were not timed to the walking phase but rather to the predefined second of the recording. The low number of perturbations will have been assigned post-hoc to an approximate phase leaving very few repetitions (and probably non some conditions of some subjects) and jittery in timing. This would make the timing of the perturbations so imprecise that the whole study is useless and should be repeated.

 

- Also, many details of the protocol and methods are not provided and make it impossible to judge the quality of the data. For example, since there is a large body of literature on the kinematics, it is not acceptable to only stick to the descriptive level for these parameters.

 

- Using the SPM simply with paired t-tests is not appropriate. Appropriate correction for multiple testing must be applied here.

 

Specific issues:

 

Introduction:

 

- The introduction focuses heavily on old age, but only young sporty female subjects are included in the study

 

- The only motivation for this study is that joint torques have not been reported for perturbed gait (“However, to the best of our knowledge, no one has so far studied the extreme values of the joint torques in perturbated [sic!] non-dominant limbs at Initial Contact, Mid Stance, and Pre-Swing altogether.”) whereas not research question and no hypotheses are provided.

 

Materials and methods

 

Participants:

- Were the participants students of sports education? This would be relevant information, since these can be expected to be more sports-affine than the average women of this age group

 

Measurement protocol:

 

“three walks:”

- how long were these gaits? how long was the initialization time?

 

“non-dominant limb”: 

- how was this determined; were right- and non-dominant legged subjects excluded?

 

“Magnitude 5” means what? 

- what acceleration and 

- how long until the new belt speed?

- how much time until the belt speed was reset to normal

- how much belt-offset (in m) does this perturbation evoke?

- which was the direction of acceleration: did the belt speed up or slow down?

 

The perturbations were apparently not timed to the walking phase, but in the 30th, 40th, 50th etc second of the measurement. In that case, 5 perturbations in three recordings does not seem much. 

- how were the perturbations binned to phase and how many repetitions (min, mean, max) per phase condition and subject?

- how much variation with respect to the walking phase?

 

stride length: 

- why so complicated: usually, the calibration is aligned with the belt, and so you would only have to use the x (or y, depending on the alignment).

 

Fig. 1: The figure is difficult to read like this. However, the “initial contact” perturbation in the upper row shows no deviation of the left lower leg. Rather, it is the third row that deviates with respect to the other two conditions (phase 2). 

- It would be good to have non-perturbed a reference figure (possibly greyed) behind each of the figures to see the influence of the perturbations

- I again ask how well the timing of the perturbations was to the walking phase. If indeed the perturbations were not timed to the walking phase but rather to the second of the recording, the whole study is useless and should be repeated.

 

 

Fig 2: How were means and stdev calculated? Across all trials or on the means of the subjects?

 

Author Response

Dear Reviewer. Responses are attached. 

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

According to the authors, the aim of this study is to examine the effect of acceleration of one belt of a treadmill during three different phases of the gait cycle on kinematic and kinetic parameters and relate these changes to unperturbed gait.

Comments in attached pdf file.

 

Comments for author File: Comments.pdf

Comments on the Quality of English Language

Author Response

Dear Reviewer. Responses are attached. 

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

This nice paper investigates postural control and gait response to mechanical perturbations during different phases of the gait cycle (Initial Contact, Mid Stance, and Pre-Swing) using a dual-belt treadmill and a motion capture system in a laboratory setting. Although only twenty-one healthy young women were in the study, some interesting results were obtained.

The paper follows good research methods and protocols. The discussion is based on the main findings. On the other hand, the generalization to older people or for rehabilitation is controversial. Results from young, healthy individuals may not directly apply to older adults or those with health conditions. The physiological and biomechanical responses to perturbations can vary significantly across age groups and health statuses. Moreover, using high-intensity protocols derived from young, healthy participants might lead to inappropriate or unsafe rehabilitation practices if not properly adjusted for the target individual’s capabilities. I suggest the authors highlight these issues in the conclusion chapter.

I did not notice major English language issues on the paper.

 

Author Response

We want to thank you for dedicating your time to reviewing our manuscript and providing such positive feedback on our work. We have carefully considered your suggestions and have made revisions accordingly. In particular, we have addressed the concern regarding the generalization of our findings to older populations or for rehabilitation purposes. We apologize for any overreaching conclusions and have added a section titled ‘Practical Application’ where we elaborate further on the potential benefits and emphasize the importance of expert assessment when programming rehabilitation protocols based on research such as ours.

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The authors have provided an excellent revision of the original manuscript. It is now very much better to understand. The improved figures also help very much. The revised introduction now fits the research and sufficiently substantiates the research objectives. 

I only have two questions left:

1. you now describe the perturbation direction and the change in belt velocity, but I should need to know the belt acceleration to reach the velocity changes. Moreover I still could not find the duration of the perturbation and the size of the perturbation in m (e.g. assuming an infinite acceleration a perturbation of 1 s would lead to a perturbation of 0.5 m - the left belt would move 0.5 m further than the right one).

2. I could still not understand exactly on what criteria the phase was determined. I gather the Motec system automatically determined the phase. Was this on the basis of the marker movement? Or rather the percentage of the average walking cycle duration with respect to the heel strike? Or still differently?

Author Response

Reviewer 1

The authors have provided an excellent revision of the original manuscript. It is now very much better to understand. The improved figures also help very much. The revised introduction now fits the research and sufficiently substantiates the research objectives. I only have two questions left:

1. you now describe the perturbation direction and the change in belt velocity, but I should need to know the belt acceleration to reach the velocity changes. Moreover I still could not find the duration of the perturbation and the size of the perturbation in m (e.g. assuming an infinite acceleration a perturbation of 1 s would lead to a perturbation of 0.5 m - the left belt would move 0.5 m further than the right one).

Thank you for your question. We completed the manuscript by incorporating additional information found in the system and *.mox files generated by D-flow. We also added figures to the manuscript illustrating the increase in velocity during the generation of perturbations. Similar information can be found in the papers:

• Hepp, J.; Shiraishi, M.; Tran, M.; Henson, E.; Ananthanarayanan, M.; Soangra, R. Exploring Teslasuit’s Potential in Detecting Sequential Slip-Induced Kinematic Changes among Healthy Young Adults. Sensors 2023, 23, 6258. https://doi.org/10.3390/s23146258
• Sessoms PH, Wyatt M, Grabiner M, Collins JD, Kingsbury T, Thesing N, Kaufman K. Method for evoking a trip-like response using a treadmill-based perturbation during locomotion. J Biomech. 2014 Jan 3;47(1):277-80. doi: 10.1016/j.jbiomech.2013.10.035

We hope that we have now cleared up any doubts.

 

2. I could still not understand exactly on what criteria the phase was determined. I gather the Motec system automatically determined the phase. Was this on the basis of the marker movement? Or rather the percentage of the average walking cycle duration with respect to the heel strike? Or still differently?

Thank you for your question. Motek automatically determines the phases of the gait cycle based on ground reaction forces and body markers. However, the manufacturers do not provide a detailed explanation of this procedure in their instructions, nor have we found any papers that describe these elements explicitly. You can find all related papers on the Motek website (https://knowledge.motekmedical.com/research/). The studies that offer more detailed descriptions of these procedures are focused on Motek Caren, but it is unclear if the same specifications apply to Motek Grail.

• Hepp, J.; Shiraishi, M.; Tran, M.; Henson, E.; Ananthanarayanan, M.; Soangra, R. Exploring Teslasuit’s Potential in Detecting Sequential Slip-Induced Kinematic Changes among Healthy Young Adults. Sensors 2023, 23, 6258. https://doi.org/10.3390/s23146258
• Sessoms PH, Wyatt M, Grabiner M, Collins JD, Kingsbury T, Thesing N, Kaufman K. Method for evoking a trip-like response using a treadmill-based perturbation during locomotion. J Biomech. 2014 Jan 3;47(1):277-80. doi: 10.1016/j.jbiomech.2013.10.035

Reviewer 2 Report

Comments and Suggestions for Authors

Please find attached my comments.

Comments for author File: Comments.pdf

Comments on the Quality of English Language

OK.

Author Response

Thank you very much for your review. Please find the answers in the attached file. 

Author Response File: Author Response.pdf

Round 3

Reviewer 2 Report

Comments and Suggestions for Authors

Some minor comments.

Comments for author File: Comments.pdf

Comments on the Quality of English Language

Author Response

Thank you for review. Please find the answers in the attached file. 

Author Response File: Author Response.pdf