Changes in Muscle Activity Imbalance of the Lower Limbs Following 3 Weeks of Supplementary Body-Weight Unilateral Training

Round 1

Reviewer 1 Report

General comments

The study has potential practical applications, however I cannot ignore the fact the lack of a control group renders much of the analysis and interpretation of the data redundant.

For the study to be accepted for publication and the analysis valid a control groups is required. The authors may wish to resubmit elsewhere as a case study.

Abstract

Line 12, in the title it is stated that the work will analyse changes in functional asymmetry, let here you state that changes in “muscle activity”, this is not the same thing. Please be consistent.

Line 13, age should be reported to zero decimal places, report all values to the number of decimal places to which they are recorded. Also, stature is more appropriate than “body height”. Training experience should also be to zero decimal places.

Line 13, what evaluations? More information is required here. Were measures taken pre and post intervention, please be clear.

Line 17, Which specific muscles within the quads, hamstrings and glutes?

Lines 18-19, information on the shorts material is not required here.

Line 21, imbalance is more appropriate than disbalance.

Introduction

I would delete the first 2 sentences, they do not provide any useful information to the reader.

Line 35-36, is there no more recent data than this, the data you refer to is at least 5 years old and is therefore unlikely to be relevant.

Line 46, I would cite these references earlier to better support your point.

Line 49, insufficient inhibition of what?

Line 50-51, I would delete this sentence.

Line 54, this is not strictly correct, it provides information on the magnitude of muscle activation, not simply whether the muscle is active or not.

Line 56, change SEMG to sEMG.

Lines 56 – 59, much of this information is not necessary and in some cases is incorrect, I am also not sure what point the authors are making here, please consider re writing to improve clarity.

Lines 63 – 67, these sentences do not make sense, please re write.

The rationale for the study is not well presented, you present no evidence that a supplementary body weight based training programme will have any positive effects on muscular imbalances. The efficacy of this needs to be discussed throughout the intro as this is what you are investigating here.

Lines 70-72, how exactly to athletes learn to activate their muscles, I am very sceptical of this statement and I would strongly consider rephrasing this information.

Lines 72-74, why do you hypothesis this, you haven’t presented any information which indicates a training programme of this nature would be effective.

Methods

As per my previous comment re reporting values to the correct number of decimal places.

Lines 101 – 102, surely participants should have ran at speeds based on a percentage of their maximum speed or maximal aerobic speed? In my opinion on blanket speed for all participants is not appropriate here.

Stats

I am confused how data were analysed here, as you recorded EMG from 8 separate muscles yet analyse the data across 3 groups, please can you clarify how the data were pooled to constitute Q, H and G?

Results

As previously stated, imbalance is more appropriate than disbalance here.

So the analyses were run on mean difference between right and left limbs for each muscle group, is this correct? If so this needs to be clarified within the methods.

Figure 1 is very very poorly presented, it appears to be copy and pasted directly from excel. Please properly format the figure, remove the gridlines etc.

I would also like to see the individual muscle group data, not all the musculature you have assessed within each muscle group will response in the same way to the training provided.

Also a major problem here is that you have no control group, as such how can you be sure that the improvements in imbalances are not simple due to the football training conducted, testing was conducted in season right?

Discussion

As you don’t have a control group and the players were performing additional sport specific training you cannot say your intervention was effective. I do concede, from a practical perspective it is likely that the intervention did have a positive effect on improving strength imbalances. However, it is extremely bad science to conclude this based on your design and analysis.

Author Response

General comments

The study has potential practical applications, however I cannot ignore the fact the lack of a control group renders much of the analysis and interpretation of the data redundant.

For the study to be accepted for publication and the analysis valid a control groups is required. The authors may wish to resubmit elsewhere as a case study.

We sincerely thank the Reviewers for careful peer-reviewing the manuscript and for their valuable comments provided in the review letter. Below, we have included a response letter where we have replied item-by-item to the comments provided by the Reviewers. We have highlighted the changes within the manuscript in yellow. We feel that the manuscript is improved in the light of the suggested changes.

We agree with the reviewer that the lack of a control group does not allow us to conclusively state that the change in the pattern of muscle activity due to the supplementary training, or from the soccer training itself. However, due to the elite level of participants, the sample was small, and dividing it into a control group would significantly reduce its power. Nevertheless, we believe that the results obtained can provide valuable information for the design of future research, and also for trainers and practitioners.

Abstract

Line 12, in the title it is stated that the work will analyse changes in functional asymmetry, let here you state that changes in “muscle activity”, this is not the same thing. Please be consistent.

Reply: According to the Reviewer’s suggestion we decided to change the title of the manuscript and use “muscle activity imbalance” term throughout the manuscript.

Line 13, age should be reported to zero decimal places, report all values to the number of decimal places to which they are recorded. Also, stature is more appropriate than “body height”. Training experience should also be to zero decimal places.

Reply: Changes has been made as suggested by Reviewer.

Line 13, what evaluations? More information is required here. Were measures taken pre and post intervention, please be clear.

Reply: Thank you for this comment. According to the Reviewer’s suggestion the sentence has been changed to: “The evaluations of lower-limbs muscle activity imbalance via surface electromyography (sEMG) were performed twice (pre- and post-intervention), at a three-week interval.”

Line 17, Which specific muscles within the quads, hamstrings and glutes?

Reply: Shorts are measuring the sEMG data from the area of quadriceps femoris, hamstrings, and gluteal muscles. The limitation of electrodes embedded in the fabric of the shorts relates to the inability to measure specific muscles (e.g., vastus lateralis) within the entire muscle group (e.g., quadriceps)

Lines 18-19, information on the shorts material is not required here.

Reply: We have deleted this information as suggested by Reviewer.

Line 21, imbalance is more appropriate than disbalance.

Reply: Corrections have been done as suggested by Reviewer.

Introduction

I would delete the first 2 sentences, they do not provide any useful information to the reader.

Reply: According to the Reviewer’s suggestion we decided to delete those sentences.

Line 35-36, is there no more recent data than this, the data you refer to is at least 5 years old and is therefore unlikely to be relevant.

Reply: We decided to keep this citation due to the fact that it is a study that analyzed a long period of time and considered a very large sample size. So far, no research of comparable quality has emerged in the existing literature on the subject.

Line 46, I would cite these references earlier to better support your point.

Reply: As suggested by the Reviewer, the sentences have been moved to the beginning of the introduction. Line 31-37

Line 49, insufficient inhibition of what?

Reply: We decided to delete that sentence.

Line 50-51, I would delete this sentence.

Reply: We have deleted this sentence as suggested by Reviewer

Line 54, this is not strictly correct, it provides information on the magnitude of muscle activation, not simply whether the muscle is active or not.

Line 56, change SEMG to sEMG.

Lines 56 – 59, much of this information is not necessary and in some cases is incorrect, I am also not sure what point the authors are making here, please consider re writing to improve clarity.

Reply: Thank you for pointing this out. We agree with the Reviewer and decided to rewrite whole paragraph. Line: 46-61

Lines 63 – 67, these sentences do not make sense, please re write.

Reply: As mentioned above, we decided to rewrite whole paragraph. Line: 46-61

The rationale for the study is not well presented, you present no evidence that a supplementary body weight based training programme will have any positive effects on muscular imbalances. The efficacy of this needs to be discussed throughout the intro as this is what you are investigating here.

Reply: Thank you for this comment. The whole paragraph has been rewritten and currently provide a brief review of the literature. Line: 46-61

Lines 70-72, how exactly to athletes learn to activate their muscles, I am very sceptical of this statement and I would strongly consider rephrasing this information.

Lines 72-74, why do you hypothesis this, you haven’t presented any information which indicates a training programme of this nature would be effective.

Reply: Thank you for this comment. The whole paragraph has been rewritten. Line: 46-61

Methods

As per my previous comment re reporting values to the correct number of decimal places.

Reply: Correction has been done as suggested by the Reviewer.

Lines 101 – 102, surely participants should have ran at speeds based on a percentage of their maximum speed or maximal aerobic speed? In my opinion on blanket speed for all participants is not appropriate here.

Reply: The 18 km/h speed of running was selected since it was considered as the low range value of a high-speed running zone in previous studies in soccer players (Gimenez et al., 2020; García-Unanue et al., 2018; Casamichana et al., 2013). Moreover, it was a value that was considered safe by all participants. This information has been added in the procedure section Line: 90-92.

Gimenez, J.V.; Jimenez-Linares, L.; Garcia-Unanue, J.; Sanchez-Sanchez, J.; Gallardo, L.; Felipe, J.L. Analyse Success Model of Split Time and Cut-Off Point Values of Physical Demands to Keep Category in Semi-Professional Football Players. Appl. Sci. 2020, 10, 5299, doi:10.3390/app10155299.

García-Unanue, J.; Pérez-Gómez, J.; Giménez, J.-V.; Felipe, J.L.; Gómez-Pomares, S.; Gallardo, L.; Sánchez-Sánchez, J. Influence of Contextual Variables and the Pressure to Keep Category on Physical Match Performance in Soccer Players. PLOS ONE 2018, 13, e0204256, doi:10.1371/journal.pone.0204256.

Casamichana, D.; Castellano, J.; Calleja-Gonzalez, J.; San Román, J.; Castagna, C. Relationship Between Indicators of Training Load in Soccer Players: J. Strength Cond. Res. 2013, 27, 369–374, doi:10.1519/JSC.0b013e3182548af1.

 Stats

I am confused how data were analysed here, as you recorded EMG from 8 separate muscles yet analyse the data across 3 groups, please can you clarify how the data were pooled to constitute Q, H and G?

Reply: The average muscle activity imbalance between lower limbs for each muscle group was used for analysis. As we mentioned above, the limitation of electrodes embedded in the fabric of the shorts relates to the inability to measure specific muscles (e.g., vastus lateralis) within the entire muscle group (e.g., quadriceps)

Results

As previously stated, imbalance is more appropriate than disbalance here.

Reply: As suggested we have use “muscle activity imbalance” term throughout the manuscript.

So the analyses were run on mean difference between right and left limbs for each muscle group, is this correct? If so this needs to be clarified within the methods.

Reply: Correct. As suggested, this information has been provided in Electromyography section Line 113-114. “The average muscle activity imbalance between lower limbs for each muscle group was used for further analysis.”

Figure 1 is very very poorly presented, it appears to be copy and pasted directly from excel. Please properly format the figure, remove the gridlines etc.

I would also like to see the individual muscle group data, not all the musculature you have assessed within each muscle group will response in the same way to the training provided.

Reply: We decided to remove the Figure 1, since its replicate data from the Table 1. As we mentioned earlier the limitation of electrodes embedded in the fabric of the shorts relates to the inability to measure specific muscles (e.g., vastus lateralis) within the entire muscle group (e.g., quadriceps).

Also a major problem here is that you have no control group, as such how can you be sure that the improvements in imbalances are not simple due to the football training conducted, testing was conducted in season right?

Discussion

As you don’t have a control group and the players were performing additional sport specific training you cannot say your intervention was effective. I do concede, from a practical perspective it is likely that the intervention did have a positive effect on improving strength imbalances. However, it is extremely bad science to conclude this based on your design and analysis.

Reply: We agree with the reviewer that the lack of a control group does not allow us to conclusively state that the change in the pattern of muscle activity due to the supplementary training but to the soccer training itself. However, due to the elite level of participants, the sample was small, and dividing it into a control group would significantly reduce its power. Therefore, we have highlighted this issue several times in the discussion and softened the provided statements. Nevertheless, we believe that the results obtained can provide valuable information for the design of future research, and also for trainers and practitioners.

Reviewer 2 Report

Disbalance is key to the paper but only mentioned for the first time in the last line of the introduction. The authors are suggested to clarify what is meant by disbalance. Is it between muscle groups in one leg (L134 mention disbalance between muscle groups) or between similar muscle groups between legs. A clear description of disbalance and how it is being calculated is required and/or need clarification.

It seems that the same data is presented in Table 1 and Figure 1. Figure 1 can be deleted.

The authors need to provide information that treadmill running speed was allowed to be similar for all participants as it can be assumed that maximal running velocity is different so participants were tested at different percentages of their maximal running speed. Is the observed disbalance independent of running speed? This needs to be discussed.

In the text of the results section, there is no references to Table 1.

L77. Change training experience “12.4 ± 4.53” to “12.4 ± 4.5”

I suggest to provide subject characteristics age, height and body mass without decimal places.

L102. How long were they running on the treadmill. In addition, please clarify when sEMGs were collected/analysed.

L102. A speed of 18 km/h may be fatiguing depending on how long subject were running for, so manuscript needs to be clear on recording of sEMGs during the treadmill run.

L105. Please clarify what is meant by “2 short accelerations”

L124. Please define ARV, could be done in L110.

Author Response

Disbalance is key to the paper but only mentioned for the first time in the last line of the introduction. The authors are suggested to clarify what is meant by disbalance. Is it between muscle groups in one leg (L134 mention disbalance between muscle groups) or between similar muscle groups between legs. A clear description of disbalance and how it is being calculated is required and/or need clarification.

We sincerely thank the Reviewers for careful peer-reviewing the manuscript and for their valuable comments provided in the review letter. Below, we have included a response letter where we have replied item-by-item to the comments provided by the Reviewers. We have highlighted the changes within the manuscript in yellow. We feel that the manuscript is improved in the light of the suggested changes.

Reply: Thank you for this comment. The introduction section has been considerably rewritten. Line 31-37 and 46-61.

It seems that the same data is presented in Table 1 and Figure 1. Figure 1 can be deleted.

Reply: Thank you for pointing this out. According to the suggestion, we have deleted Figure 1.

The authors need to provide information that treadmill running speed was allowed to be similar for all participants as it can be assumed that maximal running velocity is different so participants were tested at different percentages of their maximal running speed. Is the observed disbalance independent of running speed? This needs to be discussed.

Reply: The 18 km/h speed of running was selected since it was considered as the low range value of a high-speed running zone in previous studies in soccer players (Gimenez et al., 2020; García-Unanue et al., 2018; Casamichana et al., 2013). Moreover, it was a value that was considered safe by all participants. This information has been added in the procedure section Line: 90-92: “This treadmill running speed was chosen since it was considered as the low range value of a high-speed running zone in previous studies in soccer players [25–27] and was well tolerated by all participants of this study.”

Gimenez, J.V.; Jimenez-Linares, L.; Garcia-Unanue, J.; Sanchez-Sanchez, J.; Gallardo, L.; Felipe, J.L. Analyse Success Model of Split Time and Cut-Off Point Values of Physical Demands to Keep Category in Semi-Professional Football Players. Appl. Sci. 2020, 10, 5299, doi:10.3390/app10155299.

García-Unanue, J.; Pérez-Gómez, J.; Giménez, J.-V.; Felipe, J.L.; Gómez-Pomares, S.; Gallardo, L.; Sánchez-Sánchez, J. Influence of Contextual Variables and the Pressure to Keep Category on Physical Match Performance in Soccer Players. PLOS ONE 2018, 13, e0204256, doi:10.1371/journal.pone.0204256.

Casamichana, D.; Castellano, J.; Calleja-Gonzalez, J.; San Román, J.; Castagna, C. Relationship Between Indicators of Training Load in Soccer Players: J. Strength Cond. Res. 2013, 27, 369–374, doi:10.1519/JSC.0b013e3182548af1.

 In the text of the results section, there is no references to Table 1.

Reply: Thank you for pointing this out. The Table 1 has been cited in the result section, Line: 134

L77. Change training experience “12.4 ± 4.53” to “12.4 ± 4.5”

I suggest to provide subject characteristics age, height and body mass without decimal places.

Reply: Changes has been made according to the Reviewer suggestion.

L102. How long were they running on the treadmill. In addition, please clarify when sEMGs were collected/analysed.

Reply: Thank you for this comment. As suggested by the Reviewer, we have provided the details. Line 89-90: “The sEMG data were collected during two 10 s runs (separated by a 1 min rest) at a speed of 18km/h on a treadmill (Matrix T5X) at baseline and after 3 weeks of training.” And Line 98-102: “The bipolar electrode pairs are embedded onto the internal surface of shorts and measure the average rectified sEMG signal, on the distal part of the Q, H, G, and the reference electrodes are located longitudinally along the left and right lateral sides (over tractus iliotibialis) providing valid and repeatable data [28–30]. However, it should be emphasized that they are unable to measure specific muscles (e.g., vastus lateralis) within the overall muscle group (e.g., quadriceps).” Line 113-114: “The average muscle activity imbalance between lower limbs for each muscle group was used for further analysis.”

L102. A speed of 18 km/h may be fatiguing depending on how long subject were running for, so manuscript needs to be clear on recording of sEMGs during the treadmill run.

Reply: As mentioned above, the 18 km/h speed of running was selected since it was considered as the low range value of a high-speed running zone in previous studies in soccer players (Gimenez et al., 2020; García-Unanue et al., 2018; Casamichana et al., 2013). Moreover, it was a value that was considered safe by all participants. This information has been added in the procedure section Line: 90-92. Participants performed two 10 s runs. Line 89-90: “The sEMG data were collected during two 10 s runs (separated by a 1 min rest) at a speed of 18km/h on a treadmill (Matrix T5X) at baseline and after 3 weeks of training.”

L105. Please clarify what is meant by “2 short accelerations”

Reply: According to the suggestion we have provided this information.

L124. Please define ARV, could be done in L110.

Reply: Correction has been done.

Reviewer 3 Report

Study examined the effects of a short-term supplementary body-weight training program on changes in the muscle 10 activity imbalance of lower-limbs during high-speed running in soccer players.

Experiment is properly prepared. All parts of manuscript is easy to follow and clear for readers. 

Methodology section is well prepared.

Discussion includes interesting comparisons to other works in the field of presented research area.

Round 2

Reviewer 2 Report

Thanks for addressing my comments and suggestions.

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

This study seems to have focus on muscle activity during running following a resistance training program. The analysis of the data and the presentation of the data is unclear and very confusing.

EMG recordings were made in both legs but not clear which one is dominant and non-dominant and this being an issue is discussed. The data presentation needs substantial clarification.

Do we need “Changes in” in the title. Please reconsider.

L11. The aim needs to be revised. There is no mention of training.

L19-20. Please clarify “Changes in muscle activity after 3 weeks of sports specific movement patterns were statistically significant”. Are you referring here to muscle activity during running?

L20 and L24. Is disproportion the same as disbalance. Please be consistent in terminology.

L23. Please delete “Obtained”

L23. Change “glute” to “gluteal”

L24. The conclusion should be clear that the changes were due to sport-specific resistance training.

L24. Disbalance during what? Please clarify.

P2, L43. Please clarify “indicating insufficient inhibition

The introduction need to provide some information on the training and justification on the training.

L61. The aim needs to be revised. There is no mention of training.

L65. There was no control group. Why not? Please provided strong justification for the design of your study.

L70. “(nr RSA)”. Is this correct? Was this the approval code?

L74. As this was during the competitive season, more information needs to be provided on other training sessions and games played. How can you be sure that the observations were not just do to other activities in the 3-4 week period.

L75. Please clarify why the exercise were sport-specific. Specific for which sport (I assume football) but why.

Glute, glutes and gluteal muscles are used in the paper. I suggest to be consistent with terminology. In addition, “glute” or glutes” are colloquial, in my view.

L79. Please clarify that the EMG recording was during running. In addition, what was the reason for 18km/hr.

L105. Please provide detailed information on how “functional asymmetry” was determined.

L109. What was the coefficient of variation of quantification of muscle activity (and functional assymetry) during treadmill running at 18 km/h. The authors need to provide the coefficient of variation values.

Fig 1 legend. Is “specific movement pattern training” different than sport-specific training. Please be consistent in terminology.

Fig.1 It is not clear what is baseline and what is post-intervention data.

Ls 145-146. “A decreasing asymmetry was observed for the quadriceps muscles but the changes were not statistically significant.” You cannot state a decreasing asymmetry, there was no change.

Throughout the paper statements are made about changes but then not backed up with statistical significance. Please changes those statements throughout the paper.

Reviewer 2 Report

Applied sciences review

General comments

 Overall a poorly presented and confusing study to read. The aim of the work is at no point clear and insufficient and in some cases incorrect information is provided in numerous sections. The only section that is at an acceptable standard for publication is the EMG analysis section. See below specific comments;

Abstract

Line 11, this is not the aim I was expecting based on the title.

Line 12, sex of the players is needed, some other descriptive characteristics would also be helpful.

Line 12, you cant just say “the evaluations” what evaluations? You haven’t even told the reader what is being evaluated yet.

Line 21, change disbalance to imbalance

After the reading the rest of your abstract it is apparent that the aim doesn’t match the content of your analysis. In the aims you state that running patterns are analysed, yet your primary discussion is around muscular imbalances. The title also seems inappropriate.

The final statement around injuries is too speculative for an abstract, please re word or remove this.

Introduction

The first statement around injury requires at least one supporting reference.

Soccer is not a sport discipline, it’s simply a sport, and unless you provide specific information on the demands of the sport with citations to support your statements this sentence is not worth including.

A reference is required for the rates of femoral tendon injuries.

Line 33, are these risk factors actually statistically predictive or are they merely association with the injuries, these are not the same thing. Please clarify.

Line 35, Change side-to-side to left to right

Line 36-38, a reference is required to support this statement

Line 38-39, again a reference is required to support this statement

Line 43, please be clear what you are referring to by “insufficient inhibition”

Line 44, you should not use the word significant unless you are referring to statistics

Line 47, motor entities sounds strange in English, please re word this

Line 49, this is not strictly correct, EMG gives information of the magnitude of neuromuscular activity and not “whether a muscle is active or not”

Line 51, what exactly is meant by speed and load data here, please be clear what specific metrics you are referring to

Line 53-55, please provide more information as to why this EMG assessment method is particularly relevant to this project.

Line 56-57, this sentence does not make sense in English, please re word.

After reading the abstract and intro I am very confused as to what the aim of this study is, here it seems the focus of the study is changes in activity patters across different running speeds, yet in the abstract you discuss a training intervention. Much of this needs to be re written to improve clarity.

Methods

 The sex of the participants is needed.

Reported all values to the number of decimal places to which they are recorded, i.e. age should not contain any decimal places.

The SI unit for stature is m and not cm

Line 68, change written consent, to written informed consent

Line 70, what does ( nr RSA) mean?

Line 75, you state the players performed strength training based on movement patterns, what movement patterns?

Line 77, much more justification is needed on the choice of exercise here.

Line 79, for all equipment and software you refer to you need to state the model, manufacturer and manufacturer location.

Line 81, so participants ran once, for 30 s at 18 km/h? if so why, much more detail and justification for this protocol is required. More detailed information is also needed on the BIA protocol.

The EMG section in the methods is well written and contains the appropriate level of detail required. This is not the case for the rest of the methods section, much of this needs to be re written.

More information on your statistical analyses is needed, were the variables normally distributed or not? Was change examined using raw data? What about any differences at baseline? It is also not clear what is the primary effect your seeking to analyse.

After reading the abstract, intro and now methods section I am still not completely clear as to what this study is trying to achieve.

Results

In table 1 the number of decimal places within variables is inconsistent, also in some cases . is used for decimal place and in other , is used.

Figure 1 is very poorly presented with the abstracts not being labelled.

Discussion

Line 139, how can you attribute anything to strength when strength wasn’t even measured here?

Line 145-146, if the change was not statistically significant then there was no change, basic statistics here.

Your data do not support your conclusions, particularly the statement around injury.

Reviewer 3 Report

The authors present a study evaluating changes in functional asymmetry of the lower limbs in 15 professional soccer players following a short 3-week unilateral bodyweight resistance training intervention. Although this topic may be of interest to the field there are components of the manuscript that are lacking in detail and clarity. General and specific comments can be found below.

Specific:

L13: 'with a three-week interval'

L29: 'are related with'

L36-38: This statement does not read well.

L78: Appears to be a double space after unilaterally.

In the abstract the p values appear as P=0.01 whereas other parts it is denoted with a comma. Please be consistent.

L197: 95% confidence intervals?

L138: 'unilateral resistance training'

Major:

Overall, the introduction is limited in that it does not really introduce the topic well. For example, there is no presentation of previous resistance studies, their effectiveness, structure etc in soccer. Hence, the reader does not really get a feel for your study until the methods section.

More detail about the training intervention is required. For example, how much rest between sets and exercises, when was it performed in relation to training (before or after) and competition?

There is a lack of information about electrode placement in relation to anatomical landmarks. This makes the study difficult to reproduce.

Why only a three-week intervention? This seems short and importantly the rationale for this has not been presented by the authors. Moreover, why only the sue of bodyweight exercises?

Were any other functional tests of limb/muscle strength conducted? This would help make the findings more convincing.

It is not clear exactly what is being presented in Table 1 and Figure 1. Units of measurement are not denoted and axis labels are missing. It is also unclear how total muscle activity is less than the other muscle groups even if this is an averaged value. Overall the presentation of the results requires significant amendment.

What type of ANOVAs was used and were there any post-hoc follow-up tests?

Raw traces of EMG data from an example participant before and after the intervention would be advantageous and this is commonly shown in similar studies. It also provides a visual depiction of the data.

The discussion is limited and does not reflect on the data presented in the study and thus, comparison to other relevant literature.

L160: It is unclear what ‘inner structure’ means in this context.