Effects of a Rehabilitation Exercise Program Using Electro Muscle Stimulation following Anterior Cruciate Ligament Reconstruction on the Circumference, Activity, and Function of the Quadriceps Muscle

Round 1

Reviewer 1 Report (Previous Reviewer 2)

I don't have further questions.

Author Response

I don't have further questions..

- We thank the reviewers for their guidance for further improving our revised manuscript (applsci-2288158) entitled “Effects of a Rehabilitation Exercise Program using Electro Muscle Stimulation following Anterior Cruciate Ligament Reconstruction on the Circumference, Activity, and Function of the Quadriceps Muscle”.

Reviewer 2 Report (Previous Reviewer 3)

The authors showed how an exercise-based rehabilitation program can benefit from electrical muscle stimulation for the recovery of the patient undergoing reconstruction surgery of the anterior cruciate ligament. The authors have certainly improved the study compared to the previous review but in my opinion some points still need to be improved:

Where is the study design? are we faced with an RCT? Indeed, the study shows an experimental group and a control group. Therefore, it is appropriate to follow the CONSORT guidelines for RCT studies. Was the study registered on clinicaltrials.gov? How was the potential risk of BIAS managed? How was the sample size calculated? Do the improvements achieved by patients reach the MCID? The study may have an impact on the clinic, but the sample size is very small. Despite this I think it is very interesting and I ask the authors to implement the required points in order to publish the article.

Best regards

Author Response

The authors showed how an exercise-based rehabilitation program can benefit from electrical muscle stimulation for the recovery of the patient undergoing reconstruction surgery of the anterior cruciate ligament. The authors have certainly improved the study compared to the previous review but in my opinion some points still need to be improved:

 

Where is the study design? are we faced with an RCT? Indeed, the study shows an experimental group and a control group. Therefore, it is appropriate to follow the CONSORT guidelines for RCT studies.

- Thank you for your valuable opinion. The design of the study is written in line 121. This study was conducted in accordance with the CONSORT guidelines and controlled bias-related potential risk factors through an RCT.

Was the study registered on clinicaltrials.gov?

- Our study is not registered on clinicaltrials.gov, but we will make it available for registration later.

How was the potential risk of BIAS managed?

- Thank you for your valuable opinion. In this study, efforts were made not to unfairly or unfairly distort favorable or unfavorable judgments about people or objects, such as the CONSORT flowchart.

How was the sample size calculated?

- Thank you for your valuable opinion. The sample size information is added as follows. ‘The G*Power 3.1.9.2 software was used to determine the necessary number of participants for each population (Faul et al., 2007). Based on the findings of the study by Thomé et al.(2021), that confirmed the impact of isokinetic muscle function, we used an effect size of.35, a significance level of.05, and a power of.80. Given that 10 participants per group seemed to be the minimum need, 15 subjects per group were ultimately chosen.’

Faul, F., Erdfelder, E., Lang, A. G., & Buchner, A. (2007). G* Power 3: A flexible statistical power analysis program for the social, behavioral, and biomedical sciences. Behavior research methods, 39(2), 175-191.

Thomé, G. R., Costa, R. A., Marquezi, M. L., Aparecido, J. M., Durigan, J. L. Q., Amorim, C. F., & Liebano, R. E. (2021). Effects of neuromuscular electrical stimulation on torque and performance in recreational distance runners: a randomized controlled trial. Journal of Bodywork and Movement Therapies, 28, 369-375.

Do the improvements achieved by patients reach the MCID?

- Thank you for your valuable opinion. In this study, the control group compared the rehabilitation group with EMS added to the basic rehabilitation group and the exercise group, which showed that the comparison between the two groups was more effective in EMSG and that the MCID standard was reached.

The study may have an impact on the clinic, but the sample size is very small. Despite this I think it is very interesting and I ask the authors to implement the required points in order to publish the article.

 

- I appreciate the reviewer's favorable comments. We thank the reviewers for their guidance for further improving our revised manuscript (applsci-2288158) entitled “Effects of a Rehabilitation Exercise Program using Electro Muscle Stimulation following Anterior Cruciate Ligament Reconstruction on the Circumference, Activity, and Function of the Quadriceps Muscle”.

Reviewer 3 Report (Previous Reviewer 4)

In terms of clinical application, I am missing a more detailed description of the use of EMS within the rehabilitation program (the text mentions that it was used in 20 minutes outside of every 60 minutes of the therapy unit) - was this before or after the rehabilitation exercise and why? I.e. was EMSG given the same program as CONG plus 20 minutes of EMS each time? Wouldn't other physical therapy with myotrophic effect have the same effect? This is what I would expect to see in the discussion.
It is not entirely clear from the methodology how the EMG was evaluated.
Figure 2 would need a graphic edit.
The text is not easy to read but contains information that can be used further.

 

Author Response

In terms of clinical application, I am missing a more detailed description of the use of EMS within the rehabilitation program (the text mentions that it was used in 20 minutes outside of every 60 minutes of the therapy unit) - was this before or after the rehabilitation exercise and why? I.e. was EMSG given the same program as CONG plus 20 minutes of EMS each time? Wouldn't other physical therapy with myotrophic effect have the same effect? This is what I would expect to see in the discussion.

- I appreciate the kind remarks from the reviewer. For a more thorough explanation of how EMSG exercise, I updated the data below. ‘In a total of 3 sets, each exercise was done 15 times. Between sets, there was a 30-second pause, and there was a 2-minute rest in between exercises. In the same manner as CONG, EMSG carried out a rehabilitation exercise program for 40 minutes, and EMS was worn on the thighs to carry out electrical stimulation for 20 minutes. The entire EMS process is fully described in the EMS measuring technology.’

 

It is not entirely clear from the methodology how the EMG was evaluated.

- Thank you for your valuable opinion. As you noted, I updated the materials below to describe the EMG methodology.

‘Surface myoelectricity tests were carried out to exert as much force on the femoral quadriceps as possible while seated on the floor in order to assess the level of muscle activation through isometric contraction of the femoral quadriceps, and the vastus me-dialis (VM), vastus lateralis (VL), and rectus femoris (RF) were also assessed.’

 

Figure 2 would need a graphic edit.

- Thank you for your valuable opinion. Figure 2 was updated as described by the reviewer based on the further explanation of the EMS exercise approach.

 

The text is not easy to read but contains information that can be used further.

- I appreciate the reviewer's favorable comments. We thank the reviewers for their guidance for further improving our revised manuscript (applsci-2288158) entitled “Effects of a Rehabilitation Exercise Program using Electro Muscle Stimulation following Anterior Cruciate Ligament Reconstruction on the Circumference, Activity, and Function of the Quadriceps Muscle”.

Round 2

Reviewer 2 Report (Previous Reviewer 3)

I thank the authors for having edited the paper. Congratulations for the work done.

Best regards

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

Thank you for submitting this interesting manuscript. The authors have investigated the effects of post ACL surgery rehabilitation with NMES + standard exercise rehabilitation programme v only standard exercise rehabilitation. They reported interesting results with observed improvements in the Lysholm, score, muscle circumference, muscle activity and muscle function. However, there are several major issues which must be addressed before publication.

Major

-The manuscript requires extensive editing of English language and style.

-The methodology section requires greater detail and more clarity as to what was done and why. Currently, and possibly due to requirements for language editing, its unclear in sections. e.g. more details around the selection of stimulation parameters is required as they seem arbitrary. There is some discussion of parameters in the introduction but this does not link to the parameters selected.  

-The introduction doesn't build a stong enough justification for the study. Perhaps the focus could be more on how you have adapted the NMES protocol or aligned it to others in the literature. You do begin to discuss this but fail to expand. 

Minor

Be consistent with terms throughout, in particular your use of NMES. 

Line 41-43 - the opening sentence need to be re-written as current it is awkward. 

line 50 - you report  quadriceps muscle weakness of 20-30%. Specify what this is referring to. 

line 68- be more specific as to how electrical impulses are delivered to the body

line 94 -use past tense (undergo)

line 103-108 - add this to the results

Figure 1 should be made clearer as currently it is difficult to understand particularly the timeline of the intervention

line156-162 - you make no reference to the intensity at which the NMES was delivered. Was it a visible contraction, maximum tolerable intensity etc

line 181-185 - is this a standard method of assessing thigh circumference? Reference this method if so

Line 187-190 - same comment as above for EMG. Is the position used standard?

Line 270 - the studies you reference are for whole body NMES which uses a significantly different methodology with NMES super imposed to voluntary movements. Are these studies relevant?

line 292- you refer to the pulse frequency as intensity. these are different and the distinction should be made 

Line 308- this is speculative and should be supportive by a reference. 

line 309 - you need an alternative word to related.

line 330 - what are you referring here with total momentum? This isnt mentioned as an outcome in the methodology

line 342 - what do you mean by contraction locks?

line 343 - 347 - from As such... to function, this sentence is too long and difficult to read.

line 351 - you make reference to intensity but no where else in the manuscript. This needs to be discussed much earlier

Author Response

Reviewer1:

 

Thank you for submitting this interesting manuscript. The authors have investigated the effects of post ACL surgery rehabilitation with NMES + standard exercise rehabilitation programme v only standard exercise rehabilitation. They reported interesting results with observed improvements in the Lysholm, score, muscle circumference, muscle activity and muscle function. However, there are several major issues which must be addressed before publication.

- We thank the reviewers for their guidance for further improving our revised manuscript (applsci-2010303) entitled “Effects of Rehabilitation Exercise Program with Neuromuscular Electrical Stimulation after Anterior Cruciate Ligament Reconstruction on Quadriceps Muscle Circumference, Activity, and Function”. As described below, we have responded to all the comments brought up by the reviewers and incorporated all the changes suggested by the reviewer. In addition, we have received English corrections from the English grammer editing company, Editage.

 

Major

-The manuscript requires extensive editing of English language and style.

- Thank you for your valuable opinion. As you pointed out, we have done extensive editing of English and style.

 

-The methodology section requires greater detail and more clarity as to what was done and why. Currently, and possibly due to requirements for language editing, its unclear in sections. e.g. more details around the selection of stimulation parameters is required as they seem arbitrary. There is some discussion of parameters in the introduction but this does not link to the parameters selected.

- Thank you for your valuable opinion. In this study, it is important to quickly recover the circumference, activity, and function of the femoral quadriceps around the knee joint in order to quickly return to daily life after ACL surgery. Considering that muscle mass decreases by 20-30% after surgery during the introduction, we decided that recovery of variables related to the femoral parietal muscle would be important, so we chose three variables: circumference, activity, and function of the femoral parietal muscle. Also, the circumference of the femoral quadriceps was measured to indirectly evaluate the increase in muscle size as the muscle function recovers. In the future, we plan to study the degree of actual muscle improvement through ultrasound and MRI for thigh circumference and muscle size.

 

-The introduction doesn't build a stong enough justification for the study. Perhaps the focus could be more on how you have adapted the NMES protocol or aligned it to others in the literature. You do begin to discuss this but fail to expand.

- Thank you for your valuable comments. The purpose of this study was to confirm the effectiveness of the rehabilitation exercise program using NMES rather than general rehabilitation exercise, and to provide a standard program of current parameters for the effect of NMES. Therefore, the following contents were added in the introduction and discussion.

Line 74 ‘The NMES effect requires manipulation of current parameters such as amplitude of the current, pulse duration, and frequency of the pulses, which are major determinants. In addition, surface electrode properties such as size, type, and location should be considered (Maffiuletti et al., 2014).’

Line 87 ‘Therefore, the purpose of this study was to examine the effects of NMES on the muscle activity and function of the quadriceps femoris in patients undergoing ACL reconstruction, and to provide a standard program for NMES effect.’

Line 359 ‘Langeard et al. (2017) reported that performing NMES training at least 4 weeks and 2 to 4 times a week at a frequency between 20 Hz and 70 Hz is effective for muscle nerve improvement, and should be performed at a frequency above 50 Hz and at least 9 weeks to induce effects on functional parameters such as walking. Furthermore, when used to improve muscle size, structure, or function, pulse width and frequency are reported to be effective in the use of an ideal pulse current of 100-400 μs, typically transmitted at a stimulation frequency of 50-100 Hz, 5-10 s contraction (Blazevich et al., 2021; de Oliveira Melo et al., 2013). Therefore, it is judged that the NMES program for 12 weeks of 10 sec contraction 50 sec relaxation at frequencies 70 Hz and 300-400 μs pulses in this study was positive for the improvement of related parameters.’

 

Minor

Be consistent with terms throughout, in particular your use of NMES.

- Thank you for your valuable opinion. As you pointed out, we have unified the NMES terms as much as possible.

 

Line 41-43 - the opening sentence need to be re-written as current it is awkward.

- Thank you for your valuable opinion. As you pointed out, I re-written the contents of the first sentence of the introduction. The contents are as follows.

Line 41-46 ‘Anterior cruciate ligament (ACL) injury induces rotation and anterior instability of the knee joint, leading to early degeneration and chronic instability of the knee joint, so surgical reconstruction was being performed rather than conservative treatment [1]. However, after ACL reconstruction, edema and long-period non-movement may cause atrophy and weakness of the quadriceps and weakening of knee functions such as range of motion (ROM) [2,3], rehabilitation is necessary for recovery quickly after surgery.’

 

line 50 - you report quadriceps muscle weakness of 20-30%. Specify what this is referring to.

- Thank you for your valuable opinion. I modified and supplemented it with ‘muscle mass’.

 

line 68- be more specific as to how electrical impulses are delivered to the body

- Thank you for your valuable opinion. I modified it as follows: ‘NMES is an effective way in which electrical pulses delivered to muscles through electrodes placed on the skin stimulate motor nerves to induce muscle contraction and generate functionally useful movements through electrical stimulation, which can generate large forces with minimal neuromuscular fatigue.’

 

line 94 -use past tense (undergo)

- Thank you for your valuable opinion. I changed it to the past tense.

 

line 103-108 - add this to the results

- As you pointed out, I added the contents to the research results.

Figure 1 should be made clearer as currently it is difficult to understand particularly the timeline of the intervention

- Thank you for your valuable opinion. Figure 1 has been modified to make it easier to understand.

 

line156-162 - you make no reference to the intensity at which the NMES was delivered. Was it a visible contraction, maximum tolerable intensity etc

- Thank you for your valuable opinion. In this study, the NMES program was organized by referring to the reference below. And the frequencies and pulses conducted in this study are within the range of the maximum acceptance. The intensity is determined by frequency and pulse, but the word intensity is omitted.

Blazevich, A. J., Collins, D. F., Millet, G. Y., Vaz, M. A., & Maffiuletti, N. A. (2021). Enhancing adaptations to neuromuscular electrical stimulation training interventions. Exercise and sport sciences reviews, 49(4), 244.

 

line 181-185 - is this a standard method of assessing thigh circumference? Reference this method if so

- Thank you for your valuable opinion. For the recovery of muscle mass in ACL patients, the femoral circumference measurement method used in this study was used, and additional references were presented.

Soderberg, G. L., Ballantyne, B. T., & Kestel, L. L. (1996). Reliability of lower extremity girth measurements after anterior cruciate ligament reconstruction. Physiotherapy Research International, 1(1), 7-16.

Wright, A. R., Richardson, A. B., Kikuchi, C. K., Goldberg, D. B., Marumoto, J. M., & Kan, D. M. (2019). Effectiveness of accelerated recovery performance for post-ACL reconstruction rehabilitation. Hawai'i Journal of Health & Social Welfare, 78(11 Suppl 2), 41.

 

Line 187-190 - same comment as above for EMG. Is the position used standard?

- Thank you for your valuable opinion. In previous studies, the muscle activity measurement sites were measured by rectus femoris (RF), vastus lateralis (VL), and vastus medialis (VM), and were also used in this study with reference to this. Additional references are provided.

Tillin, N. A., & Folland, J. P. (2014). Maximal and explosive strength training elicit distinct neuromuscular adaptations, specific to the training stimulus. European journal of applied physiology, 114(2), 365-374.

 

Line 270 - the studies you reference are for whole body NMES which uses a significantly different methodology with NMES super imposed to voluntary movements. Are these studies relevant?

- Thank you for your valuable opinion. As you pointed out, I deleted the reference for whole body NMES. And we added references to the region of NMES after ACL reconstruction.

Xiong, J., Zhang, Q., & Li, Y. (2022). Clinical Study of Neuromuscular Electrical Stimulation in the Prevention of Deep Venous Thrombosis of Lower Extremities after Anterior Cruciate Ligament Reconstruction. Journal of Healthcare Engineering, 2022.

Glattke, K. E., Tummala, S. V., & Chhabra, A. (2022). Anterior Cruciate Ligament Reconstruction Recovery and Rehabilitation: A Systematic Review. JBJS, 104(8), 739-754.

 

line 292- you refer to the pulse frequency as intensity. these are different and the distinction should be made

- Thank you for your valuable opinion. I revised the term as you pointed out.

 

Line 308- this is speculative and should be supportive by a reference.

- Thank you for your valuable opinion. We added a reference that it is effective in improving muscle thickness through the NMES program.

Mancinelli, R., Toniolo, L., Di Filippo, E. S., Doria, C., Marrone, M., Maroni, C. R., Verratti, V., Bondi, D., Maccatrozzo, L., Pietrangelo, L., & Fulle, S. (2019). Neuromuscular electrical stimulation induces skeletal muscle fiber remodeling and specific gene expression profile in healthy elderly. Frontiers in physiology, 10, 1459.

Oliveira, P., Modesto, K. A. G., Bottaro, M., Babault, N., & Durigan, J. L. Q. (2018). Training effects of alternated and pulsed currents on the quadriceps muscles of athletes. International journal of sports medicine, 39(07), 535-540.

 

line 309 - you need an alternative word to related.

- Thank you for your valuable opinion. I modified the sentence in the text.

 

line 330 - what are you referring here with total momentum? This isnt mentioned as an outcome in the methodology

- Thank you for your valuable opinion. The ‘total momentum’ is a typo and has been modified to ‘total work’.

 

line 342 - what do you mean by contraction locks?

- Thank you for your valuable opinion. I corrected it with a word error.

 

line 343 - 347 - from As such... to function, this sentence is too long and difficult to read.

- Thank you for your valuable opinion. According to the reviewer's point, the parts that are difficult to read due to the long sentences were divided into two sentences to increase readability.

Line 351 ‘As such, it is judged that the combined treatment of NMES and other dynamic exercises (eg, plyometrics, sprints, vertical jumps) to improve muscle function in ACL patients can induce more muscle contractions. In addition, it is considered to be effective in that more fast-twitch fibers muscle are mobilized during muscle contraction, which helps to improve muscle hypertrophy and function.’

 

line 351 - you make reference to intensity but no where else in the manuscript. This needs to be discussed much earlier

- Thank you for your valuable opinion. I deleted the part related to the strength. I added the contents of ‘amplitude of the current, pulse duration, and frequency of the pulses' as shown below.

Author Response File: Author Response.docx

Reviewer 2 Report

This is a very well-written paper. The authors designed a set of valid experiments to show that Neuromuscular stimulation can help patients restore functionalities after ACL. Statistical results show that the stimulation intervention is superior to the control group, which proves the validity of the stimulation. The data size is adequate, and the methods were performed correctly. I believe that this paper is acceptabel. But please check the title. There is a 'Neu-ro-Muscu-2 lar', which should be Neuromuscular.

Author Response

- We thank the reviewers for their guidance for further improving our revised manuscript (applsci-2010303) entitled “Effects of Rehabilitation Exercise Program with Neuromuscular Electrical Stimulation after Anterior Cruciate Ligament Reconstruction on Quadriceps Muscle Circumference, Activity, and Function”. As described below, we have responded to all the comments brought up by the reviewers and incorporated all the changes suggested by the reviewer.

 

Reviewer2:

This is a very well-written paper. The authors designed a set of valid experiments to show that Neuromuscular stimulation can help patients restore functionalities after ACL. Statistical results show that the stimulation intervention is superior to the control group, which proves the validity of the stimulation. The data size is adequate, and the methods were performed correctly. I believe that this paper is acceptabel. But please check the title. There is a 'Neu-ro-Muscu-2 lar', which should be Neuromuscular.

- Thank you for your positive assessment. As per the reviewer comment, the part of the title 'Neu-ro-Muscu-2lar' was revised to 'Neuromuscular'.

Author Response File: Author Response.docx

Reviewer 3 Report

The study investigates an interesting element in the rehabilitation approach to patients after ACLR. However, the study did not detect major elements of innovation compared to the studies already present in the literature.

I think the introduction can also be expanded in the light of the latest research which compares the outcomes of patients undergoing surgery and patients following a conservative path.

 Some points are not clear to me: did the two groups perform a different exercise protocol? From what you wrote in the protocol it seems so, the infographic on line 120 instead seems to suggest something else. Please clarify this point.

Regarding the design of the study it is defined as interventional, there is a control group but I did not find any mention of a randomization system of the sample in the two groups. How were the patients distributed?

Please clarify this point.

Did the study follow guidelines such as the CONSORT guidelines?

Please implement this part.

In the materials and methods part I did not find a part describing the potential BIAS of this study.

I think it is useful to insert a flowchart and a timeline of the study.

Why did you choose 70Hz stimulation given the frequency variability found in the literature?

What was the surgical method used for the reconstruction?

 

How were the pacing electrodes placed? it could be useful to insert a photo on the positioning to make the study reproducible.

 

Another limitation of the study is represented by the fact that no follow-up was foreseen.

What is the clinical impact of this study and what does it say that is different or new compared to what is present in the literature?

 

 

Please clarify.

Best regards

Author Response

- We thank the reviewers for their guidance for further improving our revised manuscript (applsci-2010303) entitled “Effects of Rehabilitation Exercise Program with Neuromuscular Electrical Stimulation after Anterior Cruciate Ligament Reconstruction on Quadriceps Muscle Circumference, Activity, and Function”. As described below, we have responded to all the comments brought up by the reviewers and incorporated all the changes suggested by the reviewer.

 

Reviewer:

 

The study investigates an interesting element in the rehabilitation approach to patients after ACLR. However, the study did not detect major elements of innovation compared to the studies already present in the literature.

- Thank you for your valuable comments. Many studies have been reported on the effectiveness of NMES training. In addition, some studies have been conducted on patients with anterior cruciate ligament reconstruction and are reporting improvement in muscle function. However, there are insufficient studies to clearly confirm the effect of rehabilitation exercise program using NMES in the quadriceps femoris muscle activity and function after ACL reconstruction compared with a general rehabilitation exercise program. In addition, the NMES effect re-quires manipulation of current parameters such as amplitude of the current, pulse duration, and frequency of the pulses, which are major determinants. Therefore, we analyzed important and various indicators (questionnaire, thigh circumference, muscle activity, isokinetic muscle function) in the study of patients with anterior cruciate ligament reconstruction. And it was to confirm the effectiveness of the rehabilitation exercise program using NMES rather than general rehabilitation exercise, and to provide a standard program of current parameters for the effect of NMES.

 

I think the introduction can also be expanded in the light of the latest research which compares the outcomes of patients undergoing surgery and patients following a conservative path.

- Thank you for your valuable opinion. In this study, exercise was conducted on participants who received surgical treatment, but as the reviewer said, we will plan and try to study surgical treatment and conservative treatment in the future.

 

 Some points are not clear to me: did the two groups perform a different exercise protocol? From what you wrote in the protocol it seems so, the infographic on line 120 instead seems to suggest something else. Please clarify this point.

- Thank you for the good comment. As the reviewer commented, the unclear picture was revised and supplemented.

 

Regarding the design of the study it is defined as interventional, there is a control group but I did not find any mention of a randomization system of the sample in the two groups. How were the patients distributed?

Please clarify this point.

- Thank you for your valuable opinion. The randomly assigned conducted in this study was additionally described. ‘A total of 30 patients scheduled to undergo ACL reconstruction were randomly assigned to 1 of 2 groups: general rehabilitation exercise (GRE) program group (CONG, n = 15) and neuromuscular electrical stimulation group (NMESG, n = 15).’

 

Did the study follow guidelines such as the CONSORT guidelines?

Please implement this part.

In the materials and methods part I did not find a part describing the potential BIAS of this study.

- Thank you for your valuable opinion. This study followed the CONSORT guidelines and added a flow chart. In this study, such as the CONSORT flow chart, efforts were made not to unreasonably and unfairly distort judgments that are favorable or unfavorable to people or objects.

 

I think it is useful to insert a flowchart and a timeline of the study.

- Thank you for your valuable opinion. Figure 2 has been modified and supplemented to make the flow of the study easier to understand.

 

Why did you choose 70Hz stimulation given the frequency variability found in the literature?

- Thank you for your valuable opinion. In previous studies, when used to improve muscle size, structure, or function, pulse width and frequency are reported to be effective in using an ideal pulse current of 100-400 μs, typically transmitted at stimulation frequencies of 50-100 Hz, so this study selected the available range of 70 Hz frequencies.

 

What was the surgical method used for the reconstruction?

- Thank you for your valuable opinion. The surgical method used in this study was self-transplantation and was performed through one orthopedic surgeon. Additional description is provided in Line 95.

 

How were the pacing electrodes placed? it could be useful to insert a photo on the positioning to make the study reproducible.

- Thank you for your valuable opinion. Additional Figure of the attachment part of the electrode were inserted.

 

Another limitation of the study is represented by the fact that no follow-up was foreseen.

- Thank you for your valuable opinion. Added follow-up measures for limitation to Line 385. ‘Follow-up, since simply measuring the perimeter is limited in determining the actual changed size of the muscle, future studies are expected to clarify the reason for the difference in thigh circumference by identifying the difference in actual muscle size with NMES through ultrasound or MRI.’

 

What is the clinical impact of this study and what does it say that is different or new compared to what is present in the literature?

- Thank you for your valuable opinion. We believe that we have made a significant contribution to clarifying the need and effectiveness of the rehabilitation exercise program after anterior cruciate ligament reconstruction. Rehabilitation after ACL surgery is a quick return to daily life. As such, efforts are needed to reduce muscle mass and improve various problems appearing in ACL surgery, and this study attempted to confirm the effectiveness of the rehabilitation exercise program using NMES. Therefore, it was confirmed that the amplitude of the current, pulse duration, and frequency of the pulses applied in this study are more effective rehabilitation techniques for improving muscle surrounding, muscle activity during muscle contraction, and muscle function compared to general rehabilitation exercises. In addition, it is judged that a standard program for NMES effect can be provided as an ACL postoperative rehabilitation program.

Author Response File: Author Response.docx

Reviewer 4 Report

Figure 1:

picture in the middle of the table unclear

Methods:

a) It is not clear from the text whether these were planned operations or an acute solution immediately after the injury and what type of operation it was (own transplant, tissue bank transfer)

b) "all participants carried out the RHB exercise programe for 60 minutes in 12 weeks" vs. NMESG plus 20´? (line 160) - it is not clear in the text whether both groups received RHB training and the NMESG received an extra 20 minutes of NMES each time...

c) the decision about NMES 70Hz stimulation and pulsation time for contraction and relaxation is not explained or justified in the discussion

d) muscle activity (line187) - EMG of isometric contraction (sitting on the floor with knees extended - line 190) - but how the isokinetic contraction 60degrees/sec was measured in EMG in such a  position? (described in 2.8.?, why mentioned in 2.7.?)

e) no vastus medialis or lateralis "oblique" exist

Results:

a) Figures 2-5 mentioned Time: p=...???? What a time, when just 2 measurments?

b) In all EMG results just "significal increase of VMO during isokinetic contraction..." - increase of what?

 

Author Response

- We thank the reviewers for their guidance for further improving our revised manuscript (applsci-2010303) entitled “Effects of Rehabilitation Exercise Program with Neuromuscular Electrical Stimulation after Anterior Cruciate Ligament Reconstruction on Quadriceps Muscle Circumference, Activity, and Function”. As described below, we have responded to all the comments brought up by the reviewers and incorporated all the changes suggested by the reviewer.

 

Reviewer:

 

Figure 1:

picture in the middle of the table unclear

- Thank you for the good comment. As the reviewer commented, the unclear picture was revised and supplemented.

 

Methods:

1. a) It is not clear from the text whether these were planned operations or an acute solution immediately after the injury and what type of operation it was (own transplant, tissue bank transfer)

- Thank you for the good comment. In this study, most of the anterior cruciate ligament was own transplanted. In addition, both acute and planned patients were included due to anterior cruciate ligament injury, and all patients who visited the hospital were treated by the same orthopedic knee specialist and rehabilitation team. I added these contents below the line 96.

 

1. b) "all participants carried out the RHB exercise programe for 60 minutes in 12 weeks" vs. NMESG plus 20´? (line 160) - it is not clear in the text whether both groups received RHB training and the NMESG received an extra 20 minutes of NMES each time...

- Thank you for the good comment. Both groups conducted general rehabilitation exercise (GRE) program, and NMESG additionally described in line151 that NMES was performed by wearing NMES during GRE program. ‘NMESG performed the same GRE program, and electrical stimulation was performed for 20 minutes out of 60 minutes of GRE program by wearing it on the thigh.’

 

1. c) the decision about NMES 70Hz stimulation and pulsation time for contraction and relaxation is not explained or justified in the discussion

- As you pointed out, we added a discussion on determination of stimulation and pulsation time for contraction and relaxation of NMES to line 359. The contents added are as follows: ‘Langeard et al. (2017) reported that performing NMES training at least 4 weeks and 2 to 4 times a week at a frequency between 20 Hz and 70 Hz is effective for muscle nerve improvement, and should be performed at a frequency above 50 Hz and at least 9 weeks to induce effects on functional parameters such as walking. Furthermore, when used to improve muscle size, structure, or function, pulse width and frequency are reported to be effective in the use of an ideal pulse current of 100-400 μs, typically transmitted at a stimulation frequency of 50-100 Hz, 5-10 s contraction (Blazevich et al., 2021; de Oliveira Melo et al., 2013). Therefore, it is judged that the NMES program for 12 weeks of 10 sec contraction 50 sec relaxation at frequencies 70 Hz and 300-400 μs pulses in this study was positive for the improvement of related parameters.’

 

2. d) muscle activity (line187) - EMG of isometric contraction (sitting on the floor with knees extended - line 190) - but how the isokinetic contraction 60degrees/sec was measured in EMG in such a position? (described in 2.8.?, why mentioned in 2.7.?)

- As you pointed out, the explanation of the measurement posture seems to be wrong. Therefore, we modified it as follows. ‘Participants attached radio surface electromyography (EMG) for the muscle activity, which exerts maximum force on the femoral quadriceps in a sitting position on the isokinetic dynamometer (Biodex system Ⅳ, Biodex medical, NY, USA) chair.’

 

1. e) no vastus medialis or lateralis "oblique" exist

- Thank you for the good comment. As you pointed out, I deleted the "oblique".

 

Results:

1. a) Figures 2-5 mentioned Time: p=...???? What a time, when just 2 measurments?

- Thank you for your valuable opinion. The time mentioned in the results of this study means before and after intervention. Therefore, a total of two measurements were made, and pre-test before ACL surgery and post-test after exercise program for 12 weeks were measured.

 

1. b) In all EMG results just "significal increase of VMO during isokinetic contraction..." - increase of what?

- Thank you for your valuable opinion. The following results indicate a significant increase in 'muscle activity' of the VM, VL, and RF during isokinetic contraction. Therefore, we added 'muscle activity' to the results.

Author Response File: Author Response.docx

Round 2

Reviewer 3 Report

Thanks for correcting the article. Greetings