Effect of Medial-Lateral, Inferior-Superior, and Rotational Positions of Palms on Muscle Recruitment during the Push-Up Exercise^†

Round 1

Reviewer 1 Report

Dear Authors,

This manuscript is well written, and the topic is original and very interesting. It will need to be improved by just a few points.

Below are my specific comments:

Abstract

The abstract summarizes the manuscript correctly and presents important practical applications.

 

Keywords

Replace the keywords " Medial-lateral palm position; inferior-superior palm position; rotational positions of palms." with another word other than the title. To optimize the search for the manuscript through search engines, it is necessary to enter keywords other than the title.

 

 Introduction

The authors have provided a good summary of the literature in a concise way. The gap in the literature to be filled has been correctly described and the aims and hypotheses formulated are clear.

 

 Methods and Materials

The methodology was clearly explained.

The measurements taken were described correctly.

The statistics used are appropriate.

My concerns for clarification:

1. Please specify the characteristics of the study group in order to better match the conclusion. In my opinion, the statement "professional fitness athletes" is insufficient.

2. If you use the nomenclature of "participants", keep that name throughout the manuscript, avoiding the name "subjects"

 Results

The Results section was written correctly.

The tables and figures are explanatory.

 

 Discussion

The authors' discussions and conclusions are justified by the findings made.

Discussion and conclusions are written clearly and precisely. The limitations described are appropriate.

 Conclusion

The take-home message is clear.

 

References

The references cited are relevant and mostly current.

Author Response

Sub.: Revision of the manuscript ID applsci-1872604 titled ‘Effect of medial-lateral, inferior-superior, and rotational positions of palms on muscle recruitment during the push-up exercise.

 

Dear Chair,

I would like to immensely thank you for the opportunity given to revise the manuscript, ‘Effect of medial-lateral, inferior-superior, and rotational positions of palms on muscle recruitment during the push-up exercise. I would like to thank the reviewers for having spent their valuable time in going through the manuscript and for their suggestions. In my opinion, the manuscript has been revised considering all the suggestions of the reviewers.

 

The responses to the reviewers’ comments are given one after the other. The responses are highlighted in bold and italics including how the text has been modified in the revision.

 

I would like to emphasise that the content of the paper has not been previously published elsewhere or has not been submitted simultaneously for publication elsewhere. The paper has been revised in consultation with the co-authors.

 

Thank you.

 

 

Yours Sincerely,

Gunarajulu Renganathan (Co-Author)

Hiroshima University

 

 

 

 

Reviewer #1:

Suggestion 1.) This manuscript is well written, and the topic is original and very interesting. It will need to be improved by just a few points.

Below are my specific comments:

Abstract -The abstract summarizes the manuscript correctly and presents important practical applications.

 Response: Thank you very much for your suggestion and inputs.

Keywords -Replace the keywords " Medial-lateral palm position; inferior-superior palm position; rotational positions of palms." with another word other than the title. To optimize the search for the manuscript through search engines, it is necessary to enter keywords other than the title.

Response: Thank you very much for your suggestion and inputs. The following correction has been made in the manuscript.

The following excerpt has been added to the “Abstract” section of the manuscript.

Keywords: Push-up; Muscle activity; Hand Position; Palm Position; Exercise

 Introduction -The authors have provided a good summary of the literature in a concise way. The gap in the literature to be filled has been correctly described and the aims and hypotheses formulated are clear.

 Response: Thank you very much for your suggestion and inputs.

Methods and Materials- The methodology was clearly explained. The measurements taken were described correctly. The statistics used are appropriate.

Response: Thank you very much for your suggestion and inputs.

My concerns for clarification:

1. Please specify the characteristics of the study group in order to better match the conclusion. In my opinion, the statement "professional fitness athletes" is insufficient.

Response: Thanks for pointing out this suggestion. The following correction has been made in the manuscript.

The following excerpt has been added to the “Study Selection” section of the manuscript.

Fifteen professional fitness athletes participated in this study. These subjects have more than 6 hours of regular training per week. The average of each athlete's experience in professional sport is more than 10 years. Athletes were free from any mental or physical problems. Table 1 presents the anthropometric information of athletes. All volunteers were excluded if they had any injuries or comorbidity affecting push-ups such as previous orthopaedic surgery, musculoskeletal injuries, or a history of neurologic disorders. Written informed consent was obtained from all subjects. The current study protocols were in accordance with the Declaration of Helsinki.

The following excerpt has been added to the “Conclusion” section of the manuscript.

The push-up is a common activity for rehabilitation and workout. Various types of push-ups are known by varying positions of the upper body, lower limb, trunk, head, and support surfaces. The main aim of the current study was to find the relationships of muscle activation among medial-lateral, superior-inferior, rotational positions of palms. According to the results, the narrow positions of palms increased the infraspinatus, upper pectoralis major, triceps brachii (lateral and medial head), middle trapezius, and lower trapezius muscles while wide positions of palms enhanced the lower pectoralis major muscle. Superior positions of palms enhanced the upper trapezius while the inferior positions of palms increased the anterior deltoid, posterior deltoid, infraspinatus, all pectoralis major, biceps brachii, middle trapezius, and lower trapezius muscles. Internal positions of palms increased all pectoralis major muscles while external positions of palms enhanced the middle deltoid, latissimus dorsi, biceps brachii, middle trapezius, and lower trapezius muscles. The information about muscle activation during various types of push-ups can potentially help athletes, coaches, personal trainers, and clinicians to apply the modified push-up exercises to get new and useful exercise plans. For example, coaches can train their players via specific push-up exercises because they will be aware of each muscle role and muscle activation in each push-up type. Further research could evaluate the muscle synergy among various types of push-ups to find how CNS (central nervous system) controls the muscles.

2. If you use the nomenclature of "participants", keep that name throughout the manuscript, avoiding the name "subjects"

Response: Thanks for pointing out this suggestion. The suggested correction has been made in the manuscript.

Results- The Results section was written correctly. The tables and figures are explanatory.

Response: Thank you very much for your suggestion and inputs.

Discussion- The authors' discussions and conclusions are justified by the findings made. Discussion and conclusions are written clearly and precisely. The limitations described are appropriate.

Response: Thank you very much for your suggestion and inputs.

Conclusion- The take-home message is clear.

Response: Thank you very much for your suggestion and inputs.

References -The references cited are relevant and mostly current.

Response: Thank you very much for your suggestion and inputs.

Author Response File: Author Response.docx

Reviewer 2 Report

[Review Report]

Effect of medial-lateral, inferior-superior, and rotational positions of palms on muscle recruitment during the push-up exercise

 

[Introduction]

# I think the study's purpose is well explained in the introduction.

 

[Methods, Results]

Point 1: Participants

# Please provide the basis for calculating the sample size.

 

Point 2: Statistical Analysis

# Statistical analysis suitable for the research design presented by you is the result of one-way ANOVA for each of 'medial-lateral,' 'superior-inferior,' and 'rotational.' And, you only show the Post-Hoc test results in Figures 5, 6, and 7. I hope you will display one-way ANOVA results and post-test results in Figures 5, 6, and 7.

 

Point 3: Figure 5, 6, and 7

# The push-up pictures in Figures 5, 6, and 7 you presented are all the same. Please insert the push-up pictures relevant to the topic.

Author Response

Sub.: Revision of the manuscript ID applsci-1872604 titled ‘Effect of medial-lateral, inferior-superior, and rotational positions of palms on muscle recruitment during the push-up exercise.

 

Dear Chair,

I would like to immensely thank you for the opportunity given to revise the manuscript, ‘Effect of medial-lateral, inferior-superior, and rotational positions of palms on muscle recruitment during the push-up exercise. I would like to thank the reviewers for having spent their valuable time in going through the manuscript and for their suggestions. In my opinion, the manuscript has been revised considering all the suggestions of the reviewers.

 

The responses to the reviewers’ comments are given one after the other. The responses are highlighted in bold and italics including how the text has been modified in the revision.

 

I would like to emphasise that the content of the paper has not been previously published elsewhere or has not been submitted simultaneously for publication elsewhere. The paper has been revised in consultation with the co-authors.

 

Thank you.

 

 

Yours Sincerely,

Gunarajulu Renganathan (Co-Author)

Hiroshima University

 

 

 

 

 

 

 

Reviewer #2:

Suggestion 1.) [Introduction] # I think the study's purpose is well explained in the introduction.

Response: Thank you for your best comments.

Suggestion 2.) [Methods, Results]

Point 1: Participants # Please provide the basis for calculating the sample size.

Response: Thank you for your best comments. The basis for calculating the sample size were according to previous literatures and our experimental limitations.

Point 2: Statistical Analysis # Statistical analysis suitable for the research design presented by you is the result of one-way ANOVA for each of 'medial-lateral,' 'superior-inferior,' and 'rotational.' And you only show the post-Hoc test results in Figures 5, 6, and 7. I hope you will display one-way ANOVA results and post-test results in Figures 5, 6, and 7.

Response: Thanks for pointing out this suggestion. But in the manuscript one way ANOVA results and Post test results are included in the results sections.

One way ANOVA results:

Figure 5 presents the mean and standard deviation of normalized muscle activities for fourteen muscles: the anterior deltoid, middle deltoid, posterior deltoid, infraspinatus, upper pectoralis major, middle pectoralis major, lower pectoralis major, latissimus dorsi, triceps lateral, triceps medial, biceps brachii, upper trapezius, middle trapezius, and lower trapezius muscles in three medial-lateral positions of palms (narrow, normal, and wide). No significant differences were observed in medial-lateral positions of palms in the anterior deltoid, middle deltoid, middle pectoralis major, latissimus dorsi, biceps brachii, upper trapezius muscle activation (p>0.05). The narrow palm position tended to enhance muscle activation of the anterior deltoid, middle deltoid, posterior deltoid, infraspinatus, upper pectoralis major, middle pectoralis major, latissimus dorsi, triceps lateral, triceps medial, biceps brachii, upper trapezius, middle trapezius, and lower trapezius muscles while the wide palm position increased the lower pectoralis muscle by 0.69±0.06 of normalized muscle activation. The star sign indicated respective p-values<0.05 with respect to Tukey-Kramer post-hoc significant difference criterion. The greatest changes happened in infraspinatus (0.74±0.03) and lower pectoralis major (0.69±0.06).

Figure 6 shows the relationship between superior-inferior positions of palms and muscles activities during push-up exercise. The main impact of superior-inferior positions of palms affected all muscles (p<0.05) except the middle deltoid, lower pectoralis major, latissimus dorsi, triceps lateral, and triceps medial muscles (figure 6). The Inferior positions of the palm enhanced muscle activity in eight out of fourteen muscles (p<0.05) from 0.14-0.66 of normalized muscle activity in the middle deltoid, lower pectoralis major, latissimus dorsi, triceps lateral, and triceps medial muscles while the superior positions of palms tended to enhance muscle activation of the upper trapezius middle trapezius (p<0.05) (Figure 6).

Figure 7 presents the mean and standard deviation of normalized muscle activities for fourteen muscles: the anterior deltoid, middle deltoid, posterior deltoid, infraspinatus, upper pectoralis major, middle pectoralis major, lower pectoralis major, latissimus dorsi, triceps lateral, triceps medial, biceps brachii, upper trapezius, middle trapezius, and lower trapezius muscles in three rotational positions of palms (90° internal rotation, 0° rotation, and 90° external rotation). The star sign indicated respective p-values<0.05 with respect to Tukey-Kramer post-hoc significant difference criterion. No significant differences were observed in rotational positions of palms in the posterior deltoid, infraspinatus, triceps brachii lateral, triceps brachii medial, upper trapezius muscle activation. The Internal rotation of palms positions tended to enhance muscle activation of the upper pectoralis major, middle pectoralis major, and lower pectoralis major muscles while the external rotation of palms positions enhanced the anterior deltoid, middle deltoid, latissimus dorsi, biceps brachii, middle trapezius, and lower trapezius muscle. The rotational positions of palms changed muscle activation in nine out of fourteen muscles, with the highest rotational variations with external palm rotation being a 0.2 enhance in the latissimus dorsi and 0.07 decrease in lower pectoralis major. The highest deviation affected by external rotation of palms was in the biceps brachii of 0.18 while the lowest deviation was in anterior deltoid and infraspinatus muscles (around zero). The highest deviation from the internal rotation of palms was 0.14 in the middle pectoralis major (p<0.05) while the lowest deviation was in the posterior deltoid and triceps lateral muscles were 0.2 (figure 7).

Post-test results are included within the figure 5, 6 and 7 in the Results section.  

Point 3: Figure 5, 6, and 7 # The push-up pictures in Figures 5, 6, and 7 you presented are all the same. Please insert the push-up pictures relevant to the topic.

Response: Thanks for pointing out this suggestion. The main goal of inserting the pictures in bottom of figures is for understanding the phases of push-ups. Table 2 indicates about the position of palms during the push-up exercise. The following correction were made in the manuscript as per the reviewer suggestion.

The following excerpt has been added to the “Experimental Setup” section of the manuscript.

Participants warmed up and stretched for ten minutes before experiments. After warming up and stretch trainings the markers and EMG electrodes were attached on bodies. Before starting the experiments, the subjects trained for experiments to best performance. Participants executed push-up in three medial-lateral positions (narrow, normal, and wide), three superior-inferior positions (superior, normal, and inferior), and three rotational positions (internal, normal, and external) of palms. Therefore, each subject executed 9 types of push-ups. Each subject performed 5 trials for each type of push-up. The information about each type of push-up were illustrated in table 2.

The following excerpt has been added to the “Results” section of the manuscript.

The experimental results of the muscular activity during push-up exercise were explained in detail below. The push-up posture depicted below the Figures 2, 3, and 4 were shown for understanding the phases of the push-up. The information on the push-up type and positions of the palms were detailed in Table 2.

 

Reviewer 3 Report

Comments and Suggestions for Authors

 

Effect of medial-lateral, inferior-superior, and rotational positions of palms on muscle recruitment during the push-up exercise

by  Hamidreza Barnamehei, Gunarajulu Renganathan, Fatemeh Aflatounian5, Samirasadat Fatemigarakani, Ava Maboudmanesh, Aidasadat Fatahzadeh, Aram Shaabani 1and Yuichi Kurita

 The manuscript deals with the comparison of the neuromuscular activation pattern between medial-lateral, superior-inferior and rotational positions of the palms of the hands for selective muscles during push-up exercise. The results found on muscle activation during different types of push-ups can potentially help athletes, coaches, personal trainers and clinicians to apply modified push-up exercises to obtain a new systematic plan and useful exercise plans.

 Reviewer's comments:

·         The abstract should be improved, it must be more descriptive of the work presented.

·         The introduction should be improved, the state of the art of the problem to be solved is not identified, the importance of the subject matter cannot be appreciated,

·         The anthropometric parameters are very few, what other parameters did you consider?

·         Reduce the description of all figures to make it more descriptive.

·         Improve the description of the methodology, especially how the tests are developed.

·         The conclusions should be improved, these are very subjective, in the current state they do not contribute or add anything to the state of the art of the subject.

·         The contribution of the work is not really appreciated, the work is developed but what do I do with the results?

Author Response

Sub.: Revision of the manuscript ID applsci-1872604 titled ‘Effect of medial-lateral, inferior-superior, and rotational positions of palms on muscle recruitment during the push-up exercise.

 

Dear Chair,

I would like to immensely thank you for the opportunity given to revise the manuscript, ‘Effect of medial-lateral, inferior-superior, and rotational positions of palms on muscle recruitment during the push-up exercise. I would like to thank the reviewers for having spent their valuable time in going through the manuscript and for their suggestions. In my opinion, the manuscript has been revised considering all the suggestions of the reviewers.

 

The responses to the reviewers’ comments are given one after the other. The responses are highlighted in bold and italics including how the text has been modified in the revision.

 

I would like to emphasise that the content of the paper has not been previously published elsewhere or has not been submitted simultaneously for publication elsewhere. The paper has been revised in consultation with the co-authors.

 

Thank you.

 

 

Yours Sincerely,

Gunarajulu Renganathan (Co-Author)

Hiroshima University

 

 

 

 

Reviewer #3:

Comments.) ·        

The abstract should be improved, it must be more descriptive of the work presented. The introduction should be improved, the state of the art of the problem to be solved is not identified, the importance of the subject matter cannot be appreciated.

Response: Thank you very much for your suggestion and inputs. The following correction has been made in the manuscript.

The following excerpt has been added to the “Introduction” section of the manuscript.

Introduction

A push-up is a common bodyweight exercise executed by lowering and elevating the upper body while keeping the back straight (Golfeshan et al., 2020). The application of the push-up exercise may be for athletes or patients (Ebben et al., 2011). It is a closed kinetic chain exercise that involves many upper limb and core muscles (Kang et al., 2014; Lehman et al., 2008; K.-M. Park et al., 2014; Yoon & Lee, 2013; You-Sin Kim, Do-Yeon Kim, 2016). There are many muscles responsible for specific motions during push-up exercises. Although, the activation of each muscle depends on different factors such as hand position variants. It plays a key role in the co-contraction of multiple muscles such as agonist and antagonist muscles, therefore it was prescribed to athletes or patients to develop joint stability, injury prevention, and rehabilitation program by sports coaches or physiotherapists (Jung & Cho, 2015). The push-up consists of many variants such as medial-lateral, superior-inferior, and rotation variations of the palms (H Barnamehei & Abbasizadeh, 2021; Dhahbi et al., 2017). The push-up and its variants were investigated by techniques that involved surface electromyography (EMG) (Choi et al., 2017; Dhahbi et al., 2018).

Previous literature has studied the impacts of various variations of push-up separately such as different medial-lateral, superior-inferior, rotational positions, and executing the push-ups on various surfaces (Aguilera-Castells et al., 2020; Dhahbi et al., 2018). Despite the many excellent studies, there is no evidence for a relationship among various palm positions. Therefore, the main aim of the current study was to discover relationships of muscle activation among medial-lateral, superior-inferior, and rotational positions of palms during push-up exercise. Through the outcome of the study, it is possible to reveal correct understanding of the muscle functions in sport and clinical applications of this movement correctly in various hand positions.

 

The anthropometric parameters are very few, what other parameters did you consider?

Response: Thank you very much for your suggestion and inputs. The following correction has been made in the manuscript.

The following excerpt has been added to the “Study Selection” section of the manuscript.

Study Selection

Fifteen professional fitness athletes participated in this study. These subjects have more than 6 hours of regular training per week. The average of each athlete's experience in professional sport is more than 10 years. Athletes were free from any mental or physical problems. Table 1 presents the anthropometric information of athletes. All volunteers were excluded if they had any injuries or comorbidity affecting push-ups such as previous orthopaedic surgery, musculoskeletal injuries, or a history of neurologic disorders. Written informed consent was obtained from all subjects. The current study protocols were in accordance with the Declaration of Helsinki.

Table 1. Anthropometrics and experience information for the subjects.

Variables	Mean (± SD)
Age (years)	24.50 (7.50)
Weight (kg)	68.35 (7.18)
Height (cm)	175 (3.40)
Experience (years)	14 (3.50)

 

 

 

 

Reduce the description of all figures to make it more descriptive.

Response: Thank you very much for your suggestion and inputs.

Figure caption is essential to get all the complete information about the figure presented including the muscles, position of the palms, indication of coloured lines and shaded area within the figures. Figure captions are described based on the journal guidelines.

 

Improve the description of the methodology, especially how the tests are developed.

Response: Thank you very much for your suggestion and inputs. The following correction has been made in the manuscript.

The following excerpt has been added to the “Study Selection” section of the manuscript.

Study Selection

Fifteen professional fitness athletes participated in this study. These subjects have more than 6 hours of regular training per week. The average of each athlete's experience in professional sport is more than 10 years. Athletes were free from any mental or physical problems. Table 1 presents the anthropometric information of athletes. All volunteers were excluded if they had any injuries or comorbidity affecting push-ups such as previous orthopaedic surgery, musculoskeletal injuries, or a history of neurologic disorders. Written informed consent was obtained from all subjects. The current study protocols were in accordance with the Declaration of Helsinki.

 

 

Table 1. Anthropometrics and experience information for the subjects.

Variables	Mean (± SD)
Age (years)	24.50 (7.50)
Weight (kg)	68.35 (7.18)
Height (cm)	175 (3.40)
Experience (years)	14 (3.50)

 

 

 

 

 

 

The following excerpt has been added to the “Experimental setup” section of the manuscript.

Participants warmed up and stretched for ten minutes before experiments. After warming up and stretch trainings the markers and EMG electrodes were attached on bodies. Before starting the experiments, the subjects trained for experiments to best performance. Participants executed push-up in three medial-lateral positions (narrow, normal, and wide), three superior-inferior positions (superior, normal, and inferior), and three rotational positions (internal, normal, and external) of palms. Therefore, each subject executed 9 types of push-ups. Each subject performed 5 trials for each type of push-up. The information about each type of push-up were illustrated in table 2.

 

The conclusions should be improved, these are very subjective, in the current state they do not contribute or add anything to the state of the art of the subject.

Response: Thank you very much for your suggestion and inputs. The following correction has been made in the manuscript.

The Novelty of this research article is stated below:

The main objective of this paper is to find out the muscular activation pattern among the 14 muscle groups in different positions of the palms during the push-up exercise regime. Even though many researchers worked on the biomechanical and kinematic implications of the push-up, very few articles were reported on the effect of palms muscle activity during push-up exercise. Since push-up is one of the widely considered strength conditioning exercises which increases the core strength of the upper limb, shoulder, and trunk.  Hence the evaluation of the palm’s muscles with different positions during the push-up exercise could be used for muscle strength evaluation and rehabilitation techniques for patients with upper body injuries.

Although many researchers compared the difference in palm width suitable for strength and conditioning programs. But our proposed research aims to differentiate the muscular activity of all the three groups (Narrow, Normal, and Wide) utilized by conventional athletics. Hence, this research work will bring a major impact and insight into rehabilitative therapy programs and the muscular activation pattern can be tailored based on the subject's needs. The proposed research also suggests the muscle function in synchronization with motor control behaviours of the push-up in different variations.

 

The following excerpt has been added to the “Conclusion” section of the manuscript.

Conclusion

The push-up is a common activity for rehabilitation and workout. Various types of push-ups are known by varying positions of the upper body, lower limb, trunk, head, and support surfaces. The main aim of the current study was to find the relationships of muscle activation among medial-lateral, superior-inferior, rotational positions of palms. According to the results, the narrow positions of palms increased the infraspinatus, upper pectoralis major, triceps brachii (lateral and medial head), middle trapezius, and lower trapezius muscles while wide positions of palms enhanced the lower pectoralis major muscle. Superior positions of palms enhanced the upper trapezius while the inferior positions of palms increased the anterior deltoid, posterior deltoid, infraspinatus, all pectoralis major, biceps brachii, middle trapezius, and lower trapezius muscles. Internal positions of palms increased all pectoralis major muscles while external positions of palms enhanced the middle deltoid, latissimus dorsi, biceps brachii, middle trapezius, and lower trapezius muscles. The information about muscle activation during various types of push-ups can potentially help athletes, coaches, personal trainers, and clinicians to apply the modified push-up exercises to get new and useful exercise plans. For example, coaches can train their players via specific push-up exercises because they will be aware of each muscle role and muscle activation in each push-up type. Further research could evaluate the muscle synergy among various types of push-ups to find how CNS (central nervous system) controls the muscles.

The contribution of the work is not really appreciated, the work is developed but what do I do with the results?

Response: Thank you very much for your suggestion and inputs. The following correction has been made in the manuscript.

The Novelty of this research article is stated below:

The main objective of this paper is to find out the muscular activation pattern among the 14 muscle groups in different positions of the palms during the push-up exercise regime. Even though many researchers worked on the biomechanical and kinematic implications of the push-up, very few articles were reported on the effect of palms muscle activity during push-up exercise. Since push-up is one of the widely considered strength conditioning exercises which increases the core strength of the upper limb, shoulder, and trunk.  Hence the evaluation of the palm’s muscles with different positions during the push-up exercise could be used for muscle strength evaluation and rehabilitation techniques for patients with upper body injuries.

Although many researchers compared the difference in palm width suitable for strength and conditioning programs. But our proposed research aims to differentiate the muscular activity of all the three groups (Narrow, Normal, and Wide) utilized by conventional athletics. Hence, this research work will bring a major impact and insight into rehabilitative therapy programs and the muscular activation pattern can be tailored based on the subject's needs. The proposed research also suggests the muscle function in synchronization with motor control behaviours of the push-up in different variations.

The following excerpt has been added to the “Introduction” section of the manuscript.

Introduction

A push-up is a common bodyweight exercise executed by lowering and elevating the upper body while keeping the back straight (Golfeshan et al., 2020). The application of the push-up exercise may be for athletes or patients (Ebben et al., 2011). It is a closed kinetic chain exercise that involves many upper limb and core muscles (Kang et al., 2014; Lehman et al., 2008; K.-M. Park et al., 2014; Yoon & Lee, 2013; You-Sin Kim, Do-Yeon Kim, 2016). There are many muscles responsible for specific motions during push-up exercises. Although, the activation of each muscle depends on different factors such as hand position variants. It plays a key role in the co-contraction of multiple muscles such as agonist and antagonist muscles, therefore it was prescribed to athletes or patients to develop joint stability, injury prevention, and rehabilitation program by sports coaches or physiotherapists (Jung & Cho, 2015). The push-up consists of many variants such as medial-lateral, superior-inferior, and rotation variations of the palms (H Barnamehei & Abbasizadeh, 2021; Dhahbi et al., 2017). The push-up and its variants were investigated by techniques that involved surface electromyography (EMG) (Choi et al., 2017; Dhahbi et al., 2018).

Previous literature has studied the impacts of various variations of push-up separately such as different medial-lateral, superior-inferior, rotational positions, and executing the push-ups on various surfaces (Aguilera-Castells et al., 2020; Dhahbi et al., 2018). Despite the many excellent studies, there is no evidence for a relationship among various palm positions. Therefore, the main aim of the current study was to discover relationships of muscle activation among medial-lateral, superior-inferior, and rotational positions of palms during push-up exercise. Through the outcome of the study, it is possible to reveal correct understanding of the muscle functions in sport and clinical applications of this movement correctly in various hand positions.

The following excerpt has been added to the “Conclusion” section of the manuscript.

Conclusion

The push-up is a common activity for rehabilitation and workout. Various types of push-ups are known by varying positions of the upper body, lower limb, trunk, head, and support surfaces. The main aim of the current study was to find the relationships of muscle activation among medial-lateral, superior-inferior, rotational positions of palms. According to the results, the narrow positions of palms increased the infraspinatus, upper pectoralis major, triceps brachii (lateral and medial head), middle trapezius, and lower trapezius muscles while wide positions of palms enhanced the lower pectoralis major muscle. Superior positions of palms enhanced the upper trapezius while the inferior positions of palms increased the anterior deltoid, posterior deltoid, infraspinatus, all pectoralis major, biceps brachii, middle trapezius, and lower trapezius muscles. Internal positions of palms increased all pectoralis major muscles while external positions of palms enhanced the middle deltoid, latissimus dorsi, biceps brachii, middle trapezius, and lower trapezius muscles. The information about muscle activation during various types of push-ups can potentially help athletes, coaches, personal trainers, and clinicians to apply the modified push-up exercises to get new and useful exercise plans. For example, coaches can train their players via specific push-up exercises because they will be aware of each muscle role and muscle activation in each push-up type. Further research could evaluate the muscle synergy among various types of push-ups to find how CNS (central nervous system) controls the muscles.

 

Author Response File: Author Response.docx

Reviewer 4 Report

The manuscript is well structured, but it is not easy to follow the sections. Sentences are not linked. The area of the research is interesting; however, it needs a few amendments.

The introduction does not provide a proper background of the topic. I find it very general, without specific justification of muscles analyzed or how they contribute to the push up exercise. For example, in lines 3-6 you mention “many upper limb and core muscles” or “co-contraction of multiple muscles such as the agonist and antagonist muscles”, and I miss an explanation about what muscles are you talking about or their functions.

In the methods and materials section, the experimental setup (2.3) repeats twice the same information. How many repetitions of each hands position did the subjects execute?

How did you get the maximal values of the EMG signal of each muscle? Did you take the highest value in your exercises or did you ask for a maximal voluntary contraction of each muscle to normalized the EMG signal?

Most of the results are quite interesting and figures are relevant and help the reader to understand the findings of the manuscript, but I suggest putting them after the first mention of each one in the text.

In the page 7, line 2, “The greatest changes happened in infraspinatus (0.74±0.03) and lower pectoralis major (0.69±0.06).” It seems that the figure represents mean and standard deviation of normalized muscle activities, and not changes. Maybe it is more interesting to explain the difference between hand position and not only the value of the muscle activity. Something like this (with the correct values): “Infraspinatus is much more active when narrow (0.74±0.03) than normal (0.38…) or wide hands (0.35)”. Results section could be more interesting if you compare hands positions and muscle activation in this way for all bars graph (not only 7).

A more comprehensive discussion will improve your findings. There are only 5 references in this section.

Author Response

Sub.: Revision of the manuscript ID applsci-1872604 titled ‘Effect of medial-lateral, inferior-superior, and rotational positions of palms on muscle recruitment during the push-up exercise.

 

Dear Chair,

I would like to immensely thank you for the opportunity given to revise the manuscript, ‘Effect of medial-lateral, inferior-superior, and rotational positions of palms on muscle recruitment during the push-up exercise. I would like to thank the reviewers for having spent their valuable time in going through the manuscript and for their suggestions. In my opinion, the manuscript has been revised considering all the suggestions of the reviewers.

 

The responses to the reviewers’ comments are given one after the other. The responses are highlighted in bold and italics including how the text has been modified in the revision.

 

I would like to emphasise that the content of the paper has not been previously published elsewhere or has not been submitted simultaneously for publication elsewhere. The paper has been revised in consultation with the co-authors.

 

Thank you.

 

 

Yours Sincerely,

Gunarajulu Renganathan (Co-Author)

Hiroshima University

 

 

 

 

Reviewer #4:

Comments.) The manuscript is well structured, but it is not easy to follow the sections. Sentences are not linked. The area of the research is interesting; however, it needs a few amendments.

The introduction does not provide a proper background of the topic. I find it very general, without specific justification of muscles analyzed or how they contribute to the push up exercise. For example, in lines 3-6 you mention “many upper limb and core muscles” or “co-contraction of multiple muscles such as the agonist and antagonist muscles”, and I miss an explanation about what muscles are you talking about or their functions.

Response: Thank you very much for your suggestion and inputs. The following correction has been made in the manuscript. The previous literatures cited within the text details more about the muscle patterns of push-ups, co-contraction synergies, and its injury types. Also, our previous study (H Barnamehei & Abbasizadeh, 2021) provides the preliminary results and understanding of the study paradigm. This current study is the continuation of our previous study referenced above. Also, several changes were incorporated into the manuscript as per reviewer suggestion.

The following excerpt has been added to the “Introduction” section of the manuscript.

Introduction

A push-up is a common bodyweight exercise executed by lowering and elevating the upper body while keeping the back straight (Golfeshan et al., 2020). The application of the push-up exercise may be for athletes or patients (Ebben et al., 2011). It is a closed kinetic chain exercise that involves many upper limb and core muscles (Kang et al., 2014; Lehman et al., 2008; K.-M. Park et al., 2014; Yoon & Lee, 2013; You-Sin Kim, Do-Yeon Kim, 2016). There are many muscles responsible for specific motions during push-up exercises. Although, the activation of each muscle depends on different factors such as hand position variants. It plays a key role in the co-contraction of multiple muscles such as agonist and antagonist muscles, therefore it was prescribed to athletes or patients to develop joint stability, injury prevention, and rehabilitation program by sports coaches or physiotherapists (Jung & Cho, 2015). The push-up consists of many variants such as medial-lateral, superior-inferior, and rotation variations of the palms (H Barnamehei & Abbasizadeh, 2021; Dhahbi et al., 2017). The push-up and its variants were investigated by techniques that involved surface electromyography (EMG) (Choi et al., 2017; Dhahbi et al., 2018).

Previous literature has studied the impacts of various variations of push-up separately such as different medial-lateral, superior-inferior, rotational positions, and executing the push-ups on various surfaces (Aguilera-Castells et al., 2020; Dhahbi et al., 2018). Despite the many excellent studies, there is no evidence for a relationship among various palm positions. Therefore, the main aim of the current study was to discover relationships of muscle activation among medial-lateral, superior-inferior, and rotational positions of palms during push-up exercise. Through the outcome of the study, it is possible to reveal correct understanding of the muscle functions in sport and clinical applications of this movement correctly in various hand positions.

In the methods and materials section, the experimental setup (2.3) repeats twice the same information. How many repetitions of each hands position did the subjects execute?

Response: Thank you very much for your suggestion and inputs. The following correction has been made in the manuscript.

The following excerpt has been added to the “Experimental setup” section of the manuscript.

Experimental setup

Participants warmed up and stretched for ten minutes before experiments. After warming up and stretch trainings the markers and EMG electrodes were attached on bodies. Before starting the experiments, the subjects trained for experiments to best performance. Participants executed push-up in three medial-lateral positions (narrow, normal, and wide), three superior-inferior positions (superior, normal, and inferior), and three rotational positions (internal, normal, and external) of palms. Therefore, each subject executed 9 types of push-ups. Each subject performed 5 trials for each type of push-up. The information about each type of push-up were illustrated in table 2.

 

How did you get the maximal values of the EMG signal of each muscle? Did you take the highest value in your exercises, or did you ask for a maximal voluntary contraction of each muscle to normalized the EMG signal?

Response: Thank you very much for your suggestion and inputs. The following correction has been made in the manuscript.

The following excerpt has been added to the “Data analysis” section of the manuscript.

Data analysis

The kinematics and EMG signal were synchronized by Vicon Nexus software (Vicon Industries Ltd., Hampshire, United Kingdom). The EMG and kinematics data were incorporated into the Mokka software to set the onset and offset of the push-up exercises by visual inspection. The EMG signal was normalized to the maximal values of the EMG signal (highest values in experiments) to facilitate comparison among muscles, subjects, and different push-up variations

 

Most of the results are quite interesting and figures are relevant and help the reader to understand the findings of the manuscript, but I suggest putting them after the first mention of each one in the text.

Response: Thank you very much for your suggestion and inputs. The following correction has been made in the manuscript. Figures and text were arranged as per the reviewer suggestions. The changes may reflect in the final version of the manuscript due to the content addition within the manuscript.

 

In the page 7, line 2, “The greatest changes happened in infraspinatus (0.74±0.03) and lower pectoralis major (0.69±0.06).” It seems that the figure represents mean and standard deviation of normalized muscle activities, and not changes. Maybe it is more interesting to explain the difference between hand position and not only the value of the muscle activity. Something like this (with the correct values): “Infraspinatus is much more active when narrow (0.74±0.03) than normal (0.38…) or wide hands (0.35)”. Results section could be more interesting if you compare hands positions and muscle activation in this way for all bars graph (not only 7).

Response: Thank you very much for your suggestion and inputs. This current study is focused only on determining the muscle activation among medial-lateral, superior-inferior and rotational palm positions during push-up exercise. This is preliminary study represented in this manuscript. We are also focussed on palm placement and muscle synergy comparison in our upcoming publications.

 

A more comprehensive discussion will improve your findings. There are only 5 references in this section.

Response: Thank you very much for your suggestion and inputs. The following correction has been made in the manuscript. Additional references were added as per the reviewer suggestion.

 

The following excerpt has been added to the “Discussion” section of the manuscript.

Discussion

The push-up is a popular exercise to enhance shoulder stability, strength, and control. We compared muscle activities of the anterior deltoid, middle deltoid, posterior deltoid, infraspinatus, upper pectoralis major, middle pectoralis major, lower pectoralis major, latissimus dorsi, triceps lateral, triceps medial, biceps brachii, upper trapezius, middle trapezius, and lower trapezius muscles in (a) three medial-lateral positions of palms (narrow, normal, and wide), (b) three superior-inferior positions of palms (superior, normal, and inferior), and (c) three rotational positions of palms (90° internal rotation, 0° rotation, and 90° external rotation).

Physicians and trainers can alter the push-up variation for their tailored needs. Based on our results, narrow and inferior push-ups can be prescribed to improve the infraspinatus muscle. The narrow, inferior, and external push-ups can be used to boost the middle and lower trapezius muscles. The superior push-ups can use to improve the upper trapezius muscles. The external and inferior push-ups can prescribe to improve the biceps brachii muscle. The external push-ups can utilize to boost the latissimus dorsi muscle. The narrow push-ups can apply to boost the triceps brachii muscle. The external push-ups can use to improve the middle deltoid muscle. The inferior push-ups can utilize to enhance the anterior and posterior deltoid muscles. The internal and inferior push-ups can prescribe to improve all pectoralis major muscles. The superior positions of palms decreased muscle activation of all pectoralis major muscles (upper, middle, and lower) because these positions of palms increased the moment arm of the pectoralis major, consequently muscle activation of pectoralis major decreased to produce equal torques [22]. Based on the results, the muscle activity enhanced in all pectoralis major and decreased in triceps group muscles at the inferior positions of palms, supporting previous study [23]. The muscle activation of the infraspinatus increased when shifted from superior to inferior positions of palms because the moment arm of the infraspinatus is shorter at inferior positions of palms and longer at superior positions of palms [22], consequently muscle activation of the infraspinatus increased to produce equal moment. Cogley et al. (2005) evaluated pectoralis major and triceps brachii muscle activity during three different medial-lateral palm positions. They indicated in narrow palm positions muscle activity of pectoralis major and triceps brachii were high [24]. In addition, Gouvali et al. (2005) found pectoralis major muscle activity was highest when the distance between two palms was smallest (the narrow palms positions) [23]. Moreover, Ho et al. (2019) indicated muscle activity of the triceps brachii was highest in the narrow palms positions [25]. Kim et al. (2016) compared muscle activities of the deltoideus p. acromialis, pectoralis minor, pectoralis major, serratus anterior, biceps brachii, triceps brachii, latissimus dorsi, and infraspinatus among three medial-lateral palm positions, showed muscle activity of pectoralis major, triceps brachii, and infraspinatus was highest in the narrow palm’s positions [7]. Other studies such as Se-Yeon Park et. al compared two parts of the serratus anterior and the upper and lower trapezius muscles activation during push-up variations on stable and unstable bases of support. They found lower serratus anterior play key role to stable the shoulder grid during push-up [26].

Our present study includes some limitations such as the lack of female subjects in our experiments, low number of subjects, and lack of different age group subjects. It suggests the use of kinematics and muscle activity analysis at the same time to understand muscle functions and motor control behaviour of push-ups in different variations.

Author Response File: Author Response.docx

Round 2

Reviewer 3 Report

Despite the modifications made, this reviewer considers that it will be difficult for a reader to identify the importance and contribution of the results presented in the manuscript. However, the work was developed experimentally and can be improved to have a greater impact on the scientific community.

Author Response

Response: The importance and necessity of the results of this study is to compare different push-up types and the muscles involved in each types.  Because one of the challenges of trainers and physical therapists is the lack of quantitative and accurate knowledge of the activity of the muscles of the upper limbs in different types of this movement.  On the other hand, a quantitative and accurate comparison between these similar types of push-ups that widely used movement reveals the unknown aspects of the relationship between muscle activity and complex shoulder kinematic.  The necessity of conducting this research is that currently coaches, athletes, doctors, and physical therapists do not use accurate and quantitative results for different push-up types.  Accurate and practical use of each of these movements will achieve more accurate and efficient results.  Also, by using the results of this study, these people can prepare a table for their patients and prescribe different required types of this exercise based on their needs and compare the results and complete their clinical evaluations.