A Comparison of Denoising Methods in Onset Determination in Medial Gastrocnemius Muscle Activations during Stance (Version 1, Original)
|Reviewer 1 Michele Vecchio Università degli Studi di Catania, Catania, Italy||Reviewer 2 Chi Hwan Lee Department of Mechanical Engineering, Purdue University, West Lafayette, IN, USA|
Approved with revisions
Approved with revisions
Zhang, J.; Soangra, R.; E. Lockhart, T. A Comparison of Denoising Methods in Onset Determination in Medial Gastrocnemius Muscle Activations during Stance. Sci 2020, 2, 39.
Zhang J, Soangra R, E. Lockhart T. A Comparison of Denoising Methods in Onset Determination in Medial Gastrocnemius Muscle Activations during Stance. Sci. 2020; 2(2):39.Chicago/Turabian Style
Zhang, Jian; Soangra, Rahul; E. Lockhart, Thurmon. 2020. "A Comparison of Denoising Methods in Onset Determination in Medial Gastrocnemius Muscle Activations during Stance." Sci 2, no. 2: 39.
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Università degli Studi di Catania, Catania, Italy
1.A greater number of subjects would fit better this kind of study
2.Is it unclear if and how subjects’ skin was prepared before the application of the surface EMG electrodes; furthermore, did Authors follow any guideline for the correct position of them?
3. Regarding the choice of reporting only gastrocnemius medialis: Authors wrote that collected more muscles data. Probably it would have been useful to analyze at least one other muscle (for example an antagonist like the anterior tibial) in comparison.
4. In the discussion Authors mentioned the phenomenon of fiber switching into type I especially in gastrocnemius muscle in elders: a reference would be appropriate.
Response to Reviewer 1Sent on 12 Jul 2020 by Jian Zhang, Rahul Soangra, Thurmon E. Lockhart
Department of Mechanical Engineering, Purdue University, West Lafayette, IN, USA
The authors explored four different denoising techniques to determine the onset and cessation events of muscle activity under different conditions. It is interesting that the detection results of onset showed different behavior by denoising methods as well as walking speed. The authors explained the theory and experimental results to classify the pros and cons of various denoising methods and analyzed well. In the below, I listed several questions and comments to further improve the manuscript.
- In figure 3, authors marked onset and cessation by red stars. However, they are hard to see. Please use clearer marks.
- In figure 5, the authors insisted that they did not find any significant differences among older and younger participants’ muscle activation time for any denoising method. Please try to match with the y-axis scale between the two graphs in figure 5. It seems the activation time of young participants is faster than older.
- In the section of 2.3.6. Wavelet Denoising, the authors found that a decomposition level of 6 was adequate and would not remove EMG signal artifacts. What is the level and why was level 5 adequate? Please explain them.
- I agree with one of conclusion in the article that relying on only low pass filtering is not the solution to determine true muscle onset based on results. Then, the authors mentioned that “delayed onset of lower extremity muscle is an indication that the activation is stimulated by a stretch stimulus, rather than central nervous system control. Delay of gastrocnemius action until late terminal stance implies the influence of passive stretch during dorsiflexion.” I could not find that information or arguments in this article. How do you derive the conclusion? Please explain more details or use references to better understand the conclusion.
- The values, letters, and characters of x-axes and y-axes in all figures are too small which makes it difficult to see. Please enlarge and modify them to be clear.