Does the Workload Change When Using an Impact Wrench in Different Postures?—A Counter-Balanced Trial

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The authors are considering the combined effects of HAV and awkward hand-arm posture.  The use of electromyographic data and subjective perception provides an interesting approach to the method of assessing posture and HAV exposure.  The authors’ work is original and a contribution to the subject field.  The authors should be commended on the robust methodology adopted, the high-quality of the experiments conducted and the excellent manuscript that they have submitted.  A significant and interesting contribution to the field.

There are some very minor issues to be considered:

[1]   Title – change the word ‘Dose…’ to Does...

[2]   The title could be improved, a suggestion would be ‘Does the workload change when using an impact wrench in different postures? – a counter-balanced trial’

[3]   Line 231 – you state that the research conducted by Taylor et al. (2021) used a rotary drill.  That published paper refers to use of an ‘impact drill’.  The substrate used in their experiments appears to be a concrete paving slab – which would require an impact hammer action.  That research paper clearly states an impact drill was used on a substrate requiring hammer action due to the concrete substrate.  You may want to reconsider the statement you make in your manuscript with reference to this manuscript - as it is not factually correct.

[4]   Discussion – maybe highlight that a greater range of tools should be considered when experimenting with posture analysis in future research.

Comments on the Quality of English Language

No issues with the quality of the English language.  A minor issue with spelling and grammar in the title - suggestions provided in comments.

Author Response

We would like to thank Reviewers for taking the necessary time and effort to review the manuscript. We sincerely appreciate all your valuable comments and suggestions, which helped us in improving the quality of the manuscript. All questions and suggestions were answered in detail. The changes and additions have been marked in the text.

 

Reviewer 1)

The authors are considering the combined effects of HAV and awkward hand-arm posture.  The use of electromyographic data and subjective perception provides an interesting approach to the method of assessing posture and HAV exposure.  The authors’ work is original and a contribution to the subject field.  The authors should be commended on the robust methodology adopted, the high-quality of the experiments conducted and the excellent manuscript that they have submitted.  A significant and interesting contribution to the field.

There are some very minor issues to be considered:

[1]   Title – change the word ‘Dose…’ to Does...

Corrected.

[2]   The title could be improved, a suggestion would be ‘Does the workload change when using an impact wrench in different postures? – a counter-balanced trial’

Improved.

[3]   Line 231 – you state that the research conducted by Taylor et al. (2021) used a rotary drill.  That published paper refers to use of an ‘impact drill’.  The substrate used in their experiments appears to be a concrete paving slab – which would require an impact hammer action.  That research paper clearly states an impact drill was used on a substrate requiring hammer action due to the concrete substrate.  You may want to reconsider the statement you make in your manuscript with reference to this manuscript - as it is not factually correct.

Changed to: (line 264-273)

In contrast to the study by Taylor et. al. [12] in which tool vibrations differed significantly for the various working directions, no significant difference was seen for vibration expo-sure while working in three directions in this trial. This could also be due to the different type of substrate provided in the experiments. In this study we used a pre-cast wood plank, whereas the screwing tasks were mainly conducted by rotatory drive. In the study by Taylor et al. [12], a pre-cast concrete paving slab was used to analyze drilling tasks which might mainly require hammer action. The aspects of substrate and the mode of the operation such as rotating, hammering, or oscillating need to be more considered in detail by future studies. Thus, a greater range of tools with different specifications are needed to analyze the impact of the posture on the HAV

[4]   Discussion – maybe highlight that a greater range of tools should be considered when experimenting with posture analysis in future research.

Changed to: (line 270-273)

The aspects of substrate and the mode of the operation such as rotating, hammering, or oscillating need to be more considered in detail by future studies. Thus, a greater range of tools with different specifications are needed to analyze the impact of the posture on the hand-arm vibration.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

General comments
This is an experimental study describing the muscle load and subjective ratings of effort using an impact wrench in three different positions among 11 volunteers.

There could be interesting findings in the present study, and I strongly encourage the detailed biomechanical exposure assessment conducted with measurements of both postures and muscle load. However, I have a few major comments which I believe must be made clear before a possible publication.

 

Now the aim in the paper is worded:
“As it is still unknown to which extent awkward posture can modulate the impact of vibrations on the hand-arm system, the aim of this project was to investigate the impact of the combined exposures by using electromyographic data and subjective perception of the subjects during three different working directions.

 

First, I think the aim and research questions need to be clarified. Are the authors interested in describing:

 

1.      The impact on the muscle load in the shoulder, upper arm and forearm (measured by EMG and subjective ratings) from using a hand-held power tool in three different positions? or

2.      The impact on the vibration level from from using a hand-held power tool in three different positions? (why would it differ between different positions?) or

3.      The effect of vibration transmissibility/power absorption in the hand and arm when adopting different working postures? or

4.      The impact from hand-arm vibrations per se on the muscle load in the shoulder, upper arm and forearm (measured by EMG and subjective ratings)? (interesting, but not possible with the current experimental set-up)

 

Is there a hypothesis?

 

I understand that there might have been other force measures assessed, why is that not presented? Proceedings | Free Full-Text | Using an Impact Wrench in Different Working Directions—An Analysis of the Individual Forces (mdpi.com)

The methods lack details in procedures. Here an example of a description of EMG measurements can be found.
Simonsen JG et al. Assessments of Physical Workload in Sonography Tasks Using Inclinometry, Goniometry, and Electromyography. Saf Health Work. 2018 Sep;9(3):326-333. doi: 10.1016/j.shaw.2017.08.007.

The presentation regarding posture variables is a little unclear, the term used to denote radial- and ulnar deviation in the wrist (you have used radialduktion; radialabduction). 

You show box-plots of the results (whit some numbers that are not explained) but only refer to the different risk categories. I beleive it would be better to present mean values or medians depending on how the data is distributed. 

"While sagittal head inclination (Figure 5 a) was completely in the awkward range 172 when working in the upwards direction, it was in the moderate range while working in 173 the forwards and downwards directions."

What this means is really that the neck is extended when working upwards and in flexion working in the other directions (and more flexed in the downwards position compared to the forward position).

  

Examples of details that need revision

 The first word in the title is misspelled.

Is it a “counter -balanced trial” (title) or “an explorative pilot trial” (p. 5, ln 142)?

 The first sentence of the abstract is incorrect “Overhead work and awkward hand-arm posture cause unpleasant muscle load.”

Suggest to use a wording like “increases the risk of musculoskeletal symptoms” or “may increase the muscle load” or similar.

 

P 1. Ln 39-43.

Which adverse health effects can be underestimated? Raynaud’s phenomena, neurosensory symptoms or musculoskeletal symptoms?

Is it the vibrations per se that cause musculoskeletal symptoms or is it the increased load on muscles and tendons due to handling a tool?  
“Consequently, adverse health effects of HAV while adopting awkward posture can be underestimated by investigating the exposure of the device only. Thus, one investigation [9] showed that prolonged vibration exposure and constantly adopting an awkward posture can predispose the operators to suffer from hand-arm vibration syndrome plus neck and low back pain.”

The paper would merit if it was more precise and had a clear logic that – I believe starting with a clear aim and research question could help in this.

 

There is no reference to Bovenzi and all the work done by that group (several papers on MSD’s and vibration exposure), for example here is a quite recent review:

Palmer KT, Bovenzi M. Rheumatic effects of vibration at work. Best Pract Res Clin Rheumatol. 2015 Jun;29(3):424-39. doi: 10.1016/j.berh.2015.05.001. Epub 2015 May 30. PMID: 26612239; PMCID: PMC4766735.

 

 

Here are some other studies that have measured variability in vibration levels and have taken into account different working postures.

Liljelind et al. Variability in hand-arm vibration during grinding operations. Ann Occup Hyg. 2011 Apr;55(3):296-304. doi: 10.1093/annhyg/meq094.

Liljelind et al. Determinants explaining the variability of hand-transmitted vibration emissions from two different work tasks: grinding and cutting using angle grinders. Ann Occup Hyg. 2013 Oct;57(8):1065-77. doi: 10.1093/annhyg/met020.

The discussion is short and needs to be expanded and deepened. For example, it only contains two references.

Comments on the Quality of English Language

The quality of English could be improved and I also think the terminology needs improvement and could be used more consistent throughout the paper. 

 

Author Response

We would like to thank Reviewers for taking the necessary time and effort to review the manuscript. We sincerely appreciate all your valuable comments and suggestions, which helped us in improving the quality of the manuscript. All questions and suggestions were answered in detail. The changes and additions have been marked in the text.

 

Review 2)

General comments
This is an experimental study describing the muscle load and subjective ratings of effort using an impact wrench in three different positions among 11 volunteers.

There could be interesting findings in the present study, and I strongly encourage the detailed biomechanical exposure assessment conducted with measurements of both postures and muscle load. However, I have a few major comments which I believe must be made clear before a possible publication.

Now the aim in the paper is worded:
“As it is still unknown to which extent awkward posture can modulate the impact of vibrations on the hand-arm system, the aim of this project was to investigate the impact of the combined exposures by using electromyographic data and subjective perception of the subjects during three different working directions.

First, I think the aim and research questions need to be clarified. Are the authors interested in describing:

1. The impact on the muscle load in the shoulder, upper arm and forearm (measured by EMG and subjective ratings) from using a hand-held power tool in three different positions? Or

 

Added line. 67-73:

As it is still unknown to which extent awkward posture can modulate the impact of vibrations on the hand-arm system. Other investigations such as muscle activity can provide an overview about the impacts on the body, accompanying standard vibration measurements on the device. Thus, the aim of this project was to investigate the impact on the muscle load in the shoulder, upper arm and forearm by using electromyographic data and subjective perception of the subjects operating a hand-held power tool in three different positions.

2. The impact on the vibration level from from using a hand-held power tool in three different positions? (why would it differ between different positions?) or
3. The effect of vibration transmissibility/power absorption in the hand and arm when adopting different working postures? or
4. The impact from hand-arm vibrations per seon the muscle load in the shoulder, upper arm and forearm (measured by EMG and subjective ratings)? (interesting, but not possible with the current experimental set-up)

Is there a hypothesis?

Added line 65-67:

Finally, the hypothesis here is that only measuring the hand-arm vibration on the vibrat-ing tool does not describe the impact on the body of the operating people. Thus, there is an underestimation of risk assessment if there is no consideration of the posture. As it is still unknown to which extent awkward posture can modulate the impact of vibrations on the hand-arm system, other investigations such as muscle activity can provide an overview about the impacts on the body, accompanying standard vibration measurements on the device. Thus, the aim of this project was to investigate the impact on the muscle load in the shoulder, upper arm and forearm by using electromyographic data and subjective perception of the subjects using a hand-held power tool in three different positions.

I understand that there might have been other force measures assessed, why is that not presented? Proceedings | Free Full-Text | Using an Impact Wrench in Different Working Directions—An Analysis of the Individual Forces (mdpi.com)

There are some accompanied force assessments. Due to several limitations, we decided to exclude the force data. Since we were not able to measure the gripping force, which correlates more to the posture, we are planning to apply this for future analysis.

The methods lack details in procedures. Here an example of a description of EMG measurements can be found.
Simonsen JG et al. Assessments of Physical Workload in Sonography Tasks Using Inclinometry, Goniometry, and Electromyography. Saf Health Work. 2018 Sep;9(3):326-333. doi: 10.1016/j.shaw.2017.08.007.

We have added some more information as suggested: (line. 139-152)

A wireless bipolar surface Electromyography (sEMG) measuring system, Cometa Wave Plus was used to analyse muscle activity. Surface  electrode  placement  (Ambu®,  BlueSensor,  Denmark)  and  skin preparation followed the SENIAM guidelines [19]. The measurements were performed with Ag/AgCL electrodes (Kendall H 124 SG, Dublin (Ohio) USA) Since all subjects were right-handed, four transducers were placed on the right-hand side of the hand-arm system. Two pairs of adhesive circular surface electrodes were applied with a diameter of 24 mm (Fig. 3).

For M. trapezius descendens, electrodes were placed at 50% on the line from the acromion to the spine on vertebra C7.

For M. biceps brachii Electrodes were placed on the line between the medial acromion and the fossa cubit at 1/3 from the fossa cubit [19].

1. flexor carpi ulnaris and M. extensor digitorum were chosen as indicator for muscle activity during the chosen task. The electrodes for forearm muscles were applied to the most prominent part of the muscles, approximately one-third of the distance from the lateral epicondyle to the ulnar styloid [20].

The presentation regarding posture variables is a little unclear, the term used to denote radial- and ulnar deviation in the wrist (you have used radialduktion; radialabduction). 

We changed the posture variables to : (line. 131-133)

Positive values denote flexion and radial deviation, while negative values denote extension and ulnar deviation.

You show box-plots of the results (whit some numbers that are not explained) but only refer to the different risk categories. I beleive it would be better to present mean values or medians depending on how the data is distributed. 

Showing boxplots with regard to the risk categories allows for a better comparison of the posture data. They include the 50^th percentile, which is the median of the data, but also they show the distribution of all adopted angles (5th to 95^th) with regard to their participation in the risk category (colored background) at the same time. The focus here is to show the different participations in risk categories for different directions and different degree of freedoms. The explanation of the categories are highlighted in the text by : (line. 201-205)

Figure 5 shows the recorded body angles while using the impact wrench as a box plot (5th, 25th, 50th, 75th, 95th percentile). In the Figure 5 colour scaling based on risk catego-ries defined by Table 1 was also used to indicate the participation of the measured body angles in the three range of movement categories (neutral (green), moderate (yellow) and awkward (red)).

In the Figure 5 colour scaling based on risk categories defined by Table 1 was also used to indicate the participation of the measured body angles in the three range of movement categories (neutral (green), moderate (yellow) and awkward (red)).

"While sagittal head inclination (Figure 5 a) was completely in the awkward range 172 when working in the upwards direction, it was in the moderate range while working in 173 the forwards and downwards directions."

What this means is really that the neck is extended when working upwards and in flexion working in the other directions (and more flexed in the downwards position compared to the forward position).

Changed to: (line 208-222)

While the head (Figure 5 a) was completely extended when working upwards (awk-ward category), it was flexed working forwards (moderate category) and more flexed in the downwards position compared to the forward position.

When working in the upwards direction, the sagittal upper arm flexion (Fig 5 b) was completely in the awkward range. When working in the forwards direction, the work could be completed entirely in the neutral range and in the downwards direction it could be completed entirely in the moderate range.

With regard to wrist extension (Figure 5c), the upwards and forwards working direc-tions showed very similar results and were both in the moderate range. In the contrary, workings downwards resulted in wrist flexion which was entirely in the neutral range.

For wrist radial deviation (Figure 5 d) the data was in a neutral to moderate range when working in the upwards and forwards working directions. When working in the downwards direction, however, the data differs significantly. In this direction, the wrist movement was entirely in the moderate risk category, whereby the direction changed completely to ulnar deviation.

 

Examples of details that need revision

 The first word in the title is misspelled.

Has been corrected.

Is it a “counter -balanced trial” (title) or “an explorative pilot trial” (p. 5, ln 142)?

Has been corrected to counter-balanced trial.

 The first sentence of the abstract is incorrect “Overhead work and awkward hand-arm posture cause unpleasant muscle load.”

Suggest to use a wording like “increases the risk of musculoskeletal symptoms” or “may increase the muscle load” or similar.

Changed to: (line 11) Awkward hand-arm posture and overhead work increase the risk of musculoskeletal symptoms.

P 1. Ln 39-43.

Which adverse health effects can be underestimated? Raynaud’s phenomena, neurosensory symptoms or musculoskeletal symptoms?

Since we investigate the direct effect of the expositions on the muscles by superficial electromyography, the major focus is right now on the musculoskeletal symptoms. However, there might be other aspects affecting neurosensory symptoms or blood circulation, which is not possible to show with muscle activity, but still have to do with awkward posture.

Is it the vibrations per se that cause musculoskeletal symptoms or is it the increased load on muscles and tendons due to handling a tool?  

For a risk assessment of operations with a vibrating tool, especially for occupational diseases in Germany, up to now, it is assumed that only vibration causes the musculoskeletal symptoms. Thus, the aim of this study is to show, that the load on the muscle is different by different postures, although the vibration magnitude on the tool is the same. The investigation of the muscles with and without vibration is a valuable suggestion, that we need to consider in the future studies.

“Consequently, adverse health effects of HAV while adopting awkward posture can be underestimated by investigating the exposure of the device only. Thus, one investigation [9] showed that prolonged vibration exposure and constantly adopting an awkward posture can predispose the operators to suffer from hand-arm vibration syndrome plus neck and low back pain.”

Changed to: (line.31-38)

Consequently, adverse health effects of HAV while adopting awkward posture can be un-derestimated by investigating the exposure of the device only. For example, the elevated prevalence of musculoskeletal diseases observed by workers with vibrating tools can be caused by combined effects of many risk factors, such as hard physical effort, constrained postures and strong grip force [3] [4]. Recent studies [5] have also shown that operators suffer from HAV syndrome as well as neck and back pain when exposed to prolonged vi-bration and constantly adopting an awkward posture.

The paper would merit if it was more precise and had a clear logic that – I believe starting with a clear aim and research question could help in this.

The aim of the project has been identified (as suggested above) in the introduction section. Also, a hypothesis has been added into the section to clarify the purpose of the trial.

There is no reference to Bovenzi and all the work done by that group (several papers on MSD’s and vibration exposure), for example here is a quite recent review:

All suggested works have been considered and cited.

Palmer KT, Bovenzi M. Rheumatic effects of vibration at work. Best Pract Res Clin Rheumatol. 2015 Jun;29(3):424-39. doi: 10.1016/j.berh.2015.05.001. Epub 2015 May 30. PMID: 26612239; PMCID: PMC4766735.

Here are some other studies that have measured variability in vibration levels and have taken into account different working postures.

Liljelind et al. Variability in hand-arm vibration during grinding operations. Ann Occup Hyg. 2011 Apr;55(3):296-304. doi: 10.1093/annhyg/meq094.

Liljelind et al. Determinants explaining the variability of hand-transmitted vibration emissions from two different work tasks: grinding and cutting using angle grinders. Ann Occup Hyg. 2013 Oct;57(8):1065-77. doi: 10.1093/annhyg/met020.

The discussion is short and needs to be expanded and deepened. For example, it only contains two references.

The discussion has been completed, also more refences were compared as suggested.

 

Comments on the Quality of English Language

The quality of English could be improved and I also think the terminology needs improvement and could be used more consistent throughout the paper. 

We corrected some terminologies.

 

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

The ISO 5349-1 international standard for workload indicators uses only the acceleration intensity of vibration as the basis for derivation and does not consider hand-arm posture. The findings are helpful in that the workload above the head was significantly higher than in other postures, quantitatively demonstrated by the muscle activity and subjective load, and the results were well compared with the control data. In particular, the postural analysis is also carefully conducted, and the EMG activity analysis with postural conditions as preconditions is very well constructed.

 

<minor concerns>

• Is the width of the ruled line in Figure 5 appropriate?
• The decimal point in Figure 6, which is a comma, should be changed to a period.
• Is the boldface and period in "11. healthy, right" at the beginning of section 2.1 appropriate?
  

Comments on the Quality of English Language

No concerns

Author Response

We would like to thank Reviewers for taking the necessary time and effort to review the manuscript. We sincerely appreciate all your valuable comments and suggestions, which helped us in improving the quality of the manuscript. All questions and suggestions were answered in detail. The changes and additions have been marked in the text.

 

Review 3)

The ISO 5349-1 international standard for workload indicators uses only the acceleration intensity of vibration as the basis for derivation and does not consider hand-arm posture. The findings are helpful in that the workload above the head was significantly higher than in other postures, quantitatively demonstrated by the muscle activity and subjective load, and the results were well compared with the control data. In particular, the postural analysis is also carefully conducted, and the EMG activity analysis with postural conditions as preconditions is very well constructed.

 

<minor concerns>

• Is the width of the ruled line in Figure 5 appropriate?
• The line has been removed, since there is no additional information by that.
• The decimal point in Figure 6, which is a comma, should be changed to a period.
• Has been corrected.
• Is the boldface and period in "11. healthy, right" at the beginning of section 2.1 appropriate?
• Has been corrected.

 

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

I appreciate the effort from the authors to answer my comments and revise the manuscript – I think it is now clearer and more straight forward. However, I have a few minor comments that I think could be changed before publication.

 

Abstract

Ln 20-21,  

First I do not agree with that it is especially the wrist posture that is important. From figures 5-7 it seems to me that the upward position and the posture of the upper arm and head would need to be considered (also in the red risk zone).

 

Secondly, I wonder if working directions and postures of the arm and hand (and head) need to be considered while investigating risks (or effects) associated with hand-arm vibration exposure?

 

Results

Figure 5. Now I understand the figures next to the Box-plot but I still think this could be explained in the figure legend

References

Needs to be checked, there are references that are not complete (for example 13) and some have different format (ref 24)

I have not seen "Bd" in a reference before - what is that?

Author Response

Thank you very much for your comments.

 

Abstract

Ln 20-21,  

First I do not agree with that it is especially the wrist posture that is important. From figures 5-7 it seems to me that the upward position and the posture of the upper arm and head would need to be considered (also in the red risk zone).

Agreed. We changed to:

The results demonstrate that the working direction and but also more importantly the arm, wrist and head posture need to be considered while investigating the hand-arm vibration exposure.

 Secondly, I wonder if working directions and postures of the arm and hand (and head) need to be considered while investigating risks (or effects) associated with hand-arm vibration exposure?

Yes, the posture is more important than the working direction. But if there is no possibility to assess the posture, at least the documented working direction might help too.

Results

Figure 5. Now I understand the figures next to the Box plot but I still think this could be explained in the figure legend

The figure legend changed to:

Figure 5: Posture analysis for three working directions while using an impact wrench; Angels are given as Boxplots (5^th, 25^th, 50^th, 75^th, 95^th); The range of movements for each angle is given by the categories with respect to ISO TR 10687 (green=neutral, yellow=moderate and red=awkward)

 

References

Needs to be checked, there are references that are not complete (for example 13) and some have different format (ref 24)

I have not seen "Bd" in a reference before - what is that?

Bd stood for Volume. We changed the references following MDPI Style

Author Response File: Author Response.docx