Critical Ergonomics and (Dis)Comfort Factors While Performing Tasks with Hand Tools on a Ladder: A Pilot Study

Round 1

Reviewer 1 Report

This paper discusses about ergonomics and discomfort factors during performing tasks with hand tools on a ladder. It is a good topic; however some information and data should be added prior to publication. My comments are as follows.

1.       Table 1: What is the dominant arm of the participants? Did this factor have an effect on the results?

2.       2.4 Experimental Setup: The setup is very detailed, e.g. drilling height 210cm, deposited equal to 61cm, etc. Was there any specific reason regarding choosing these values? In the data analysis, these values should be considered to minimize the effect of individual differences in body characteristics including height. Did you consider any normalization procedure during data analysis?

3.       3. Postural data acquisition: Kinovea was used to acquire limb movements. Please provide the details of the measurement method. How did you measure the angle? Please also provide the results.

4.       In conclusion, it is mentioned that the perceived discomfort is always less when the operation is carried out from the ground. This is an obvious result. Did you conduct an experiment that compares between standing on ground and standing on a ladder without doing any operation? I am curious that similar result will be obtained.

5.       Knee contact on the ladder is considered to be the reason for the perceived discomfort. Did you ask the participants about the details? I thought that muscle activation for maintaining balance and muscle fatigue is the main reason for the discomfort.

6.       Can you provide a result regarding the area and time of contact between participant’s knees and parts of the ladder, as well as the relationships with the participant’s height?

Author Response

Dear reviewer, first, thank you for the constructive and useful comments to improve our work. Below are our point-by-point comments.

1. Table 1: What is the dominant arm of the participants? Did this factor have an effect on the results?

We did not evaluate the effect of the dominant arm as the sample was not significant.

In the text, from line 206 to line 208, the following sentence has been inserted:

“24 out of 26 subjects were right-handed and only 2 were left-handed. Given the limited number of left-handed subjects, it was decided not to conduct the analyzes separately as the results obtained would not have been statistically significant.”

2. 4 Experimental Setup: The setup is very detailed, e.g. drilling height 210cm, deposited equal to 61cm, etc. Was there any specific reason regarding choosing these values? In the data analysis, these values should be considered to minimize the effect of individual differences in body characteristics including height. Did you consider any normalization procedure during data analysis?

The setup was defined following a simulation carried out in DELMIA®. The experimental setup was created in a virtual environment and subsequently tested with three mannikins belonging to the 5th, 50th, and 95th percentile. The chosen solution forced the three mannequins to assume different postures but ensured the absence of reachability problems.

No normalization procedure was considered since one of the aims of the data analysis was to investigate the correlations between perceived discomfort, perceived effort, and body characteristics during the use of a standard tool, the ladder, during simple and standard tasks. Normalizing the results would have hidden these correlations.

In the text, from line 143 to line 146, the following sentence has been inserted:

“All distances reproduced in the experimental setup were initially tested in a simulation environment DELMIA®. The experimental setup was created in a virtual environment and subsequently tested with three mannikins belonging to the 5th, 50th, and 95th percentile. The chosen solution forced the three mannequins to assume different postures but ensured the absence of reachability problems.”   

3. Postural data acquisition: Kinovea was used to acquire limb movements. Please provide the details of the measurement method. How did you measure the angle? Please also provide the results.

After photographic acquisition campaign, the Kinovea® free photogrammetric software was used for processing pictures in order to measure the angles.

Measurements acquired were:

– Shoulder Flexion: considering the angle between two segments, the first one oriented in direction of the axis of the arm and the other one vertically from the head of the humerus:

– Shoulder abduction: measuring the angle between two segments, the first one coinciding with the axis of the arm, the second one vertically oriented from the head of the humerus;

– Elbow Flexion: measuring the angle between two segments, the first one oriented as the straight line passing through the humeral head and the elbow, the other one oriented from the centre of elbow joint and coincident with the forearm axis;

– Wrist Radio-ulnar deviation: it has been identified as the angle between the extension of the axis of the forearm with a segment joining the centre of the wrist with the conjunction of the third and fourth metacarpal bone (middle finger and ring finger);

– Neck frontal flexion: measured as the angle between the axis of inclination of the ground (horizontal in our case) and the perpendicular line towards the axis of upper body inclination.

In the section Postural data acquisition and from line 191 to line 192 more details and a new reference have been inserted:

“The reference position for detection and measurement of joint angles was the geometric-zero position. This position is defined as the one that allows the maximum state of comfort among the values in the “Comfort Range of Motion” (CROM) (38)” 

4. In conclusion, it is mentioned that the perceived discomfort is always less when the operation is carried out from the ground. This is an obvious result. Did you conduct an experiment that compares between standing on ground and standing on a ladder without doing any operation? I am curious that similar result will be obtained.

No such experiment was performed.

The primary aim of the questionnaire was not specifically to confirm that activities performed on the ground were less in discomfort than those performed on a ladder. The questionnaire was useful for understanding which areas of the body were most responsible for the perceived discomfort. The results of the study emerged when the questionnaire data were correlated with two objective data, CAMan and RULA®.

5. Knee contact on the ladder is considered to be the reason for the perceived discomfort. Did you ask the participants about the details? I thought that muscle activation for maintaining balance and muscle fatigue is the main reason for the discomfort.

The correlation between the perceived discomfort and the knee local discomfort is not sufficient to conclude that knee contact is the only cause of overall perceived discomfort.

However, data analysis and observation of the videos, together with the questionnaire data, led the authors to conclude that knee posture is a critical element.

The difference in knee discomfort between ladder and ground is always significant (Tables 2, 4, 6, and 8); statistical analyses show correlations between knee discomfort and perceived discomfort and effort: as perceived knee discomfort increases, the perception of global discomfort and perceived effort increases (Tables 3, 5, 7, and 9); the videos and direct observation of the participants showed continuous knee contact with the ladder during the execution of the tasks.                                                                                                                                                                                                                                                                                                                                                                                                                                                                   In the text, from line 312 to line 315, a sentence has been inserted: “The difference in knee discomfort between ladder and ground is always significant; statistical analyses show correlations between knee discomfort and perceived discomfort and effort: as perceived knee discomfort increased, the perception of global discomfort and perceived effort increased.”

6. Can you provide a result regarding the area and time of contact between participant’s knees and parts of the ladder, as well as the relationships with the participant’s height?

The actual reasons for knee discomfort were not assessed since this was not the original aim of the investigation. Additionally, the parameters to monitor to characterize the causes of knee discomfort involve parameters that have not been measured since, before the experiment, we didn’t know the results and the importance of sub-factors like the applied pressure, the area, and the time of contact.

Regarding the relationship with participants' height, the correlation analyses showed a negative correlation (Table 3 and Table 5). To increase the participants' height the discomfort knee perceived decreases. Direct observation showed that as the height of the participants increased, contact with the ladder ring was reduced until it was lost completely. Thus, the absence of pressure in the knee on the ring caused less discomfort to the subjects. 

Correlation between knee discomfort and participant height are reported in table 3 and table 5   Further investigations are possible.

In the section Conclusion, from line 317 to line 320, a new sentence has been inserted: “The results also show a correlation between knee discomfort and participants' height: to increase the participants' height the discomfort knee perceived decreases. Direct observation showed that as the height of the participants increased, contact between knees and ladder steps was reduced until it was lost completely. Thus, the absence of pressure in the knee on the step caused less discomfort to the subjects”.

In Limitation a short sentence is added about the lack of acquisition of Knee-Ladder contact parameters, that can be considered as a future development of the experiment. From line 289 to line 291.

Author Response File: Author Response.pdf

Reviewer 2 Report

The publication is a well-thought-out concept for presenting research on factors related to working with the use of a ladder. However, the research itself is of a pilot nature. Too small and a non-representative group of people who participated in the research may have a significant impact on the reliability of the research results.

The title of the publication does not precisely correspond to its content.

Nevertheless, the research topic was justified, and the research method was correctly selected as well as the way of presenting results. The methodology was well selected and applied.

The manuscript requires thorough linguistic proofreading. Careless text editing also requires a lot of corrections. These include numerous unnecessary spaces and, on the other hand, their absence in places where they should be found, incorrect period after the title of subsection 2.2. , incorrect arrangement of the text in chapter 6, incorrectly used vocabulary, inconsistent description of literature sources in their list. Furthermore, literature sources from the 1970s are not valid for citing.

The arrangement of content is mostly correct, but the manuscript should end with conclusions.

The publication requires corrections. It should not be published in its current form. 

The publication is a well-thought-out concept for presenting research on factors related to working with the use of a ladder. However, the research itself is of a pilot nature. Too small and a non-representative group of people who participated in the research may have a significant impact on the reliability of the research results.

The title of the publication does not precisely correspond to its content.

Nevertheless, the research topic was justified, and the research method was correctly selected as well as the way of presenting results. The methodology was well selected and applied.

The manuscript requires thorough linguistic proofreading. Careless text editing also requires a lot of corrections. These include numerous unnecessary spaces and, on the other hand, their absence in places where they should be found, incorrect period after the title of subsection 2.2. , incorrect arrangement of the text in chapter 6, incorrectly used vocabulary, inconsistent description of literature sources in their list. Furthermore, literature sources from the 1970s are not valid for citing.

The arrangement of content is mostly correct, but the manuscript should end with conclusions.

Author Response

Dear reviewer, first, thank you for the constructive and useful comments to improve our work. Below are our point-by-point comments.

1. The publication is a well-thought-out concept for presenting research on factors related to working with the use of a ladder. However, the research itself is of a pilot nature. Too small and a non-representative group of people who participated in the research may have a significant impact on the reliability of the research results. The title of the publication does not precisely correspond to its content. Nevertheless, the research topic was justified, and the research method was correctly selected as well as the way of presenting results. The methodology was well selected and applied.

The sample of 26 was chosen based on percentiles. The sample ranges from the 20th percentile female to the 95th percentile male, ensuring a good description of the population.  

However, given the limitations of the study and aware that in future developments it will be possible to reduce the limitations mentioned in the work, we agree that the title can be changed. The aim is to make the idea of ​​the content clearer.

The modified title: Critical ergonomics and (dis)comfort factors while performing tasks with hand tools on a ladder: a pilot study

2. The manuscript requires thorough linguistic proofreading. Careless text editing also requires a lot of corrections. These include numerous unnecessary spaces and, on the other hand, their absence in places where they should be found, incorrect period after the title of subsection 2.2. , incorrect arrangement of the text in chapter 6, incorrectly used vocabulary, inconsistent description of literature sources in their list. Furthermore, literature sources from the 1970s are not valid for citing. The arrangement of content is mostly correct, but the manuscript should end with conclusions.

Thanks for your comment.

 As suggested:

- the references have been modified (insertion of the doi, elimination of superfluous information);

- Typographical errors in the text have been removed as have superfluous spaces.

- An English revision has been done.

Regarding the literature sources from the 1970s, the authors think that they are necessary to make it clear that the "ladder issue" has been addressed in the past but almost nothing has been done over the years.

3. The arrangement of content is mostly correct, but the manuscript should end with conclusions.

As suggested, the conclusions have been reported in the last paragraph.

Author Response File: Author Response.pdf

Reviewer 3 Report

The article presents a relatively unexplored perspective in the field of ergonomics concerning the risks and hazards of posture and balance on a ladder compared to performing the same tasks on the ground. It concludes using an instrumented version of  CAMan, and RULA assessments that there are indeed dangers and discomforts that need to be addressed through a redesign of this tool. However, after a thorough examination, I have identified several areas that require attention to enhance the clarity, rigor, and adherence to academic standards in your manuscript. Below are the suggested revisions:

Methodological Concerns:

Sample Size Justification: Could you please clarify the rationale behind choosing a sample size of 26 participants? It is crucial to understand whether this number was derived from a sample size calculation or if it represents preliminary results. Providing a justification for this choice would significantly strengthen the methodological foundation of your study.

Inclusion Criteria and Participant Characteristics: The manuscript would benefit from a more detailed explanation of the inclusion criteria for participants in the preliminary measurements. Additionally, information regarding their anthropometric characteristics, age, and associated comorbidities is essential for contextualizing the findings. It is also important to confirm whether informed consent was obtained, even in this pre-experimental phase.

Demographic Data Presentation: The current presentation of demographic data seems to lack depth. Consider separating the data by gender and including additional variables such as years of work experience to offer a more comprehensive view of the sample population.

Statistical Analysis: The section discussing the evaluation of sample normality is missing. Since Spearman's correlation is employed, it implies the data may not be normally distributed. Clarifying how normality was assessed or reasoned would provide critical insight into the statistical approaches used.

Formatting and Citation Issues:

Typographical Errors: There is a typographical error double stops in Line 21 that needs correction for readability.

Figure Citation: Please ensure that the source of Figure 3 is appropriately credited to avoid issues of plagiarism if it is not original work. Proper attribution is fundamental in scholarly communication.

Software and Tool Citations: When referencing software tools such as Kinovea, CAMan, and RULA (especially if MATLAB is used), it is necessary to include comprehensive details about the creators or providing companies, including their corporate name, headquarters city, and country. This detail adds to the credibility and reproducibility of the research.

Decimal Notation Consistency: There is inconsistency in the notation of decimal values across tables (2 to 9) and their captions, with commas used in some places and periods in others. Standardizing this notation throughout the manuscript will improve consistency and readability.

These comments aim to refine your manuscript and ensure it meets the high standards of academic rigor and presentation.

Author Response

Dear reviewer, first, thank you for the constructive and useful comments to improve our work. Below are our point-by-point comments.

The article presents a relatively unexplored perspective in the field of ergonomics concerning the risks and hazards of posture and balance on a ladder compared to performing the same tasks on the ground. It concludes using an instrumented version of CAMan, and RULA assessments that there are indeed dangers and discomforts that need to be addressed through a redesign of this tool. However, after a thorough examination, I have identified several areas that require attention to enhance the clarity, rigor, and adherence to academic standards in your manuscript. Below are the suggested revisions:

1. Methodological Concerns. Sample Size Justification: Could you please clarify the rationale behind choosing a sample size of 26 participants? It is crucial to understand whether this number was derived from a sample size calculation or if it represents preliminary results. Providing a justification for this choice would significantly strengthen the methodological foundation of your study.

The sample of 26 subjects is significant at a confidence level of 95%. The sample was chosen based on percentiles The sample ranges from the 20th percentile female to the 95th percentile male, ensuring a good description of the population.  

The section Participant has been modified and a new sentence (from line 112 to line 113) has been inserted: “The sample ranges from the 20th percentile female to the 96th percentile male, ensuring a good description of the population.” 

2. Inclusion Criteria and Participant Characteristics: The manuscript would benefit from a more detailed explanation of the inclusion criteria for participants in the preliminary measurements. Additionally, information regarding their anthropometric characteristics, age, and associated comorbidities is essential for contextualizing the findings. It is also important to confirm whether informed consent was obtained, even in this pre-experimental phase.

In the preliminary test, 15 people were involved.

More details have been inserted in the text (from line 83 to line 86) as suggested.

"Informed consent was obtained. The sample consisted of 8 men and 7 women, aged between 24 and 32. The height varied from 165cm (female participant) to 180cm (male participant), no specific inclusion Criteria have been applied, but the subject does not have disabilities and has to be able to work on a ladder (no height-related dizziness has to be recorded in the subject history)"

3. Demographic Data Presentation: The current presentation of demographic data seems to lack depth. Consider separating the data by gender and including additional variables such as years of work experience to offer a more comprehensive view of the sample population.

As the sample only has 4 women separate analyzes would not be meaningful at this stage. The authors focused above all on finding a significant number of subjects capable of covering the 5th percentile female and 95th percentile male range. in future studies, it would be interesting to carry out similar analyzes considering the gender difference.   In the questionnaire there was a question on "work experience" but data analysis showed that it was not a discriminating factor for the results.

4. Statistical Analysis: The section discussing the evaluation of sample normality is missing. Since Spearman's correlation is employed, it implies the data may not be normally distributed. Clarifying how normality was assessed or reasoned would provide critical insight into the statistical approaches used.

Spearman correlation is used because the data were not normally distributed. The normality test was carried out in SPSS using the Kolmogorv-Smirnov test.

5. Formatting and Citation Issues:  Typographical Errors: There is a typographical error double stops in Line 21 that needs correction for readability.

It has been corrected.

6. Figure Citation: Please ensure that the source of Figure 3 is appropriately credited to avoid issues of plagiarism if it is not original work. Proper attribution is fundamental in scholarly communication.

A new sentence (line 177) and a new reference have been inserted.

“A body diagram similar to (42) was used to define localized ratings (Figure 3)”

7. Software and Tool Citations: When referencing software tools such as Kinovea, CAMan, and RULA (especially if MATLAB is used), it is necessary to include comprehensive details about the creators or providing companies, including their corporate name, headquarters city, and country. This detail adds to the credibility and reproducibility of the research.

New details have been inserted:

For Kinovea® in line 181,182: “The photos for each participant and each task were processed using Kinovea® software version 0.9.5-x64 (Figure 4). Kinovea is a free software application for the analysis, comparison, and evaluation of movement.”

For RULA® the reference “McAtamney L, Nigel Corlett E. RULA: a survey method for the investigation of work-related upper limb disorders. Appl Ergon. 1993;24(2):91–9. Available from: https://www.sciencedirect.com/science/article/pii/000368709390080S” has been added.

CAMan is a private tool developed by the University of Salerno. In the text, some references about the development and applications of the tool are reported.  

8. Decimal Notation Consistency: There is inconsistency in the notation of decimal values across tables (2 to 9) and their captions, with commas used in some places and periods in others. Standardizing this notation throughout the manuscript will improve consistency and readability. These comments aim to refine your manuscript and ensure it meets the high standards of academic rigor and presentation.

The notations have been modified as suggested.

Please see the attachment

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Thank you for the revision. It can be accepted for publication.

Reviewer 2 Report

Thank you for your corrections and explanations submitted to the manuscript. They are satisfying for me. I suggest you review the edition of the publication again. I do not make any suggestions for corrections to be made.

I do not make any suggestions for corrections to be made.

Reviewer 3 Report

Nice. For me, the article could be published in the current form.