Lower-Limb Electromyography Signal Analysis for the Bottom Group of Muscles Fitness Norm before and after Intensive Exercise
Round 1
Reviewer 1 Report
This article is a study of the muscle electrical activity of non-fit people before and after training a short-term training program.
This article shows that electrical activities have evolved between pre and post-training.
English writing and presentation seem good, the topic is interesting and the authors took time to explain and detail contextual information such as in the introduction. This is much appreciated.
However, this works suffer from several flaws:
- Point 1: Their no research question or hypothesis, and therefore it is not clear why the authors are measuring the electrical activity of the muscles.
- Point 2: The 3 intensity zones (low, moderate, and high) do not match actual recommendations from NSCA or ACSM concerning strength training and therefore seem arbitrary.
- Point 3: The experimental design is weak: experiments are conducted sequentially, are not randomized, and occur during the same session.
The first experiment is conducted until failure hereby raising serious doubt concerning the aptitude to pursue the procedure from there.
- Point 4: Conclusion and taken-off of this article are weak: The authors showed that training within the same condition as the test allows performing better during the test, which is basically the concept of specificity.
- Point 5: The topic of this article is more or less related to the science of exercise and does not seems to match the editorial line of this journal.
- Point 6: The material section (hardware, software, etc.) is very laconic and mainly contained within Figure 2. The authors could elaborate on it.
I would like to let the authors a right to answer in case I misunderstood something here. But in the current state, and given the lack of experimental design, I recommend rejecting this article.
Author Response
Thank you for your comments.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The topic of the article is very interesting. I am very interested in what is the division into sex and age in the study group? The research results presented in the work are very uniform. In my opinion, the test results should differ by gender.
Author Response
Thank you for your comments.
Author Response File: Author Response.pdf
Reviewer 3 Report
This study is interesting and offers new information to the field. However, there are some methodological issues that need to be fixed before the results can be considered reliable for publication.
The main problem is that the study is based on small samples (n=10, 11, 8), especially the bottom 20% group (the core study group) which has only 8 subjects. Also, with this small sample, the authors conducted parametric statistics. Two questions here: 1. why did the author not consider non-parametric statistics when testing group differences? 2. why did the authors not recruiting more subjects for the bottom group this is the group of interest?
It is obvious that the results might be implicated by this low sample size. In tables 2 and 3, there are many comparison's p levels are marginal, at 0.1, 0.07, 0.06 etc. Would this be due to statistical power? Why did the authors not address this issue and/or not getting more participants? I am concerned about the reliability of this set of results.
A limitation section is missing, the limitation section is needed to at least address the low sample size.
In the conclusion, the authors mentioned: "Previous study has been performed base on EMGs recorded in exercise and force plate experiments under different exercise intensities for three university freshmen groups with distinct levels of physical fitness, time-domain and frequency-domain analysis." Which study? Please cite the study. It looks like the current study was conducted based on this previous study but the information hasn't been provided earlier in the introduction. The authors mentioned in the last paragraph of the introduction that there was a previous study [15]; was the "previous study mentioned in the conclusion" refer to the previous study mentioned in the introduction? This needs to be clarified.
Author Response
Thank you for your comments.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
I would like to thanks the authors for taking seriously the previous comments. The manuscript is easier to read, more clear and provides a sufficient description of the experimental procedure.
Two issues remain concerning Point 2 and Point 3 of our previous exchange, which I reported here:
Point 2: The 3 intensity zones (low, moderate, and high) do not match actual recommendations from NSCA or ACSM concerning strength training and therefore seem arbitrary.
Response 2: Thank you for your comments. Considering that the subjects who performed the weight-bearing squat experiment are all freshmen, not professional athletes. Before the start of the study, some members of the Human Research Ethics (IRB) were worried that if the exercise intensity is too high, it may cause the subjects to suffer potential risks that may also make it impossible to complete the high-intensity exercise. In order to enable all three physical fitness norms to complete the exercise experiment, and to avoid the potential high-intensity injury risk of the bottom 20% groups of physical fitness norms. Therefore, the three-level exercise intensity standard for this study was established after discussion by the research team. The designed exercise intensity of this research has been appropriately explained in the revised paper. (Line 158~163 on page 4)
Response To Response 2: Thank you for providing such a description and improving the manuscript according to my comment. However, I would argue that 18 and 28 repetitions belong to the same repetition zone (muscular endurance training), and therefore that the authors have only two levels of difficulty. Above all, I personally don’t know a training program making a difference between 18 and 28 repetitions, so even if there is some statistical difference between the two-level of intensity, there will likely be no practical implication.
Point 3: The experimental design is weak: experiments are conducted sequentially, are not randomized, and occur during the same session. The first experiment is conducted until failure hereby raising serious doubt concerning the aptitude to pursue the procedure from there.
Response 3: Thank you for your valuable comments. The flowchart and description in Figure 2 (original) was caused misunderstandings by reviewer. After the completion of the no load and 1RM test, the subjects will rest for 6 days and then perform the exercise experiments and the force plate experiments. The exercise experiment intensity of this study was divided into the following three levels: light exercise (28RM), moderate exercise (18RM), vigorous exercise (8RM). After completing each exercise experiment (isotonic contraction), the force plate experiment (isometric contraction) was performed to acquire the EMG signal and the strength failure signal immediately. Rest for 3 minutes in each level of exercise experiment. The schematic diagram of experimental procedures and descriptions have been revised in this version. (Line 86~92 on page 2; on page 3; Line 131~133 on page 4)
Response To Response 3: I appreciate the efforts that were put into the figure and the description of the experiment. However, the consideration remains as exhaustion happens in all three levels and most importantly within the same session. The authors should also consider that fatigue occurs sooner in beginners. Since the study was not randomized, I honestly wonder if the results would have been the same if the order between the exercise were different.
These are strong experimental biases, which at least needs to be well stated and discussed at the end of the study.
Author Response
Thank you for your comments. Your valuable comments have been stated and discussed in the revised article.
Author Response File: Author Response.pdf
Round 3
Reviewer 1 Report
The authors answered some of the previous comments considering the experimental bias at the end of the conclusion. However:
- I highly recommend reviewing the English grammar and style l. 328-342
- "In general, more than 20RM belongs to muscle endurance training". This statement is false. According to NSCA [1], a repetition zone greater than 12 belongs to endurance training (therefore 18 and 28 reps are in the same repetition zone)
I highly recommend the authors taking into account these considerations.
[1] National Strength & Conditioning Association NSCA’s Guide to Program Design; Hoffman, J. (Ed.) Human Kinetics: Champaign, IL, USA, 2011; ISBN 978-1-4925-8277-9
Author Response
Thank you for your comments. Your valuable comments have been added in the revised article. (Line 336~337 on page 11; Line 393~394 on page 12 )
Author Response File: Author Response.pdf
