A Biomechanical Comparison between Squatbar® and Olympic Barbell
Round 1
Reviewer 1 Report
Thanks to the authors for submitting this manuscript and the editors for the opportunity to review this manuscript.
The title of the study was “A Biomechanical Comparison between Squatbar and Olympic Barbell”.
The aim of the study was to investigate kinematics, kinetics and myoelectric activity (EMG) between the Squatbar barbell and Olympic barbell when performing a 1-RM squat.
The study can be of interest for the reader of biomechanics.
The strong parts of the manuscript are:
§ It is a relevant topic for basic research.
§ The introduction is well written, organized, and the idea was clear.
Overall, you had an interesting manuscript. There are several minor comments:
§ Lines 68-73: It is not clear which previous studies indicated to this evidence, please add references to support this part.
§ Lines 128: “anatomical landmarks based on earlier research” I recommend adding more details to indicate it for the reader.
§ Line 187: Figure 4. Can you please revise the EMG unit, it seems microvolt not millivolt.
§ It might be better to write a section under the subsection name, "Practical Applications" to advise the coaches and players and highlight the results.
Author Response
Overall, you had an interesting manuscript. There are several minor comments:
- Lines 68-73: It is not clear which previous studies indicated to this evidence, please add references to support this part.
A reference has been added.
- Lines 128: “anatomical landmarks based on earlier research” I recommend adding more details to indicate it for the reader.
A detailed description of placement has now been added.
- Line 187: Figure 4. Can you please revise the EMG unit, it seems microvolt not millivolt.
It is my understanding that the abbreviation for millivolt is mV (as in figure 4), while microvolt is µV.
- It might be better to write a section under the subsection name, "Practical Applications" to advise the coaches and players and highlight the results.
Practical applications has now been included as a subsection.
Reviewer 2 Report
First of all, I would like to thank you for sending me this article for review and congratulate the authors for their initiative in this highly relevant research.
The introduction is relevant and justifies the relevance of the research, however, it is recommended to write the objective using the word "objective". For example: The objective of this research was....
It is recommended to use the Strobe Statement. There are several aspects throughout the document that are not included.
Although the authors describe the participants, the power and sample size are not indicated. It should be indicated how the sample size was calculated and what the sample power is.
The authors present a good description of the method, however, as mentioned, some aspects covered by Strobe's statement are missing. These include how the sample was accessed, how it was recruited and further specify the inclusion and exclusion criteria.
In this regard, the authors indicate that subjects were randomised. Some subjects performed the test first with the Squatbar and others used the Olympic barbell first. What criteria were used to randomise subjects in the order of barbell use?
Although the results are comprehensive and clearly shown, it is recommended that more information, such as the statistical significance value and effect size, be included in the tables.
Author Response
The introduction is relevant and justifies the relevance of the research, however, it is recommended to write the objective using the word "objective". For example: The objective of this research was....
A sentence has been revised with the use of the word objective: “Thus, the objective of the current study was to investigate kinematics, kinetics and myoelectric activity (EMG) between the Squatbar® barbell and Olympic barbell when performing a 1-RM squat.”
It is recommended to use the Strobe Statement. There are several aspects throughout the document that are not included.
The authors believe the Strobe checklist has been accounted for, where it is relevant. If the reviewer think it is necessary, please highlight the aspects of the document in need of revision.
Although the authors describe the participants, the power and sample size are not indicated. It should be indicated how the sample size was calculated and what the sample power is.
We have based our sample size upon earlier studies in squats (variability within subject on kinematics and kinetics and EMG) and performed a sample size calculation. This was now mentioned in the text:
Based upon earlier studies in squats, the minimum number of participants required was estimated by using G*Power 1 (version 3.1.9.6). The analysis indicated that at least 10 participants (α = 0.05, 1−β = 0.95, Cohen’s d = 1.2) were necessary.
The authors present a good description of the method, however, as mentioned, some aspects covered by Strobe's statement are missing. These include how the sample was accessed, how it was recruited and further specify the inclusion and exclusion criteria.
The authors believe inclusion criteria is already thoroughly stated (e.g., able to squat 1.5 x body mass in external load to IPF depth, male, absence of injury etc). However, the section has been revised to highlight recruitment of the sample “The participants who volunteered to participate were recruited from a local commercial gym, and had to declare…”
In this regard, the authors indicate that subjects were randomised. Some subjects performed the test first with the Squatbar and others used the Olympic barbell first. What criteria were used to randomise subjects in the order of barbell use?
The schedule for testing each individual participant was firstly planned. The test order was determined by an online randomizer. Thereafter, testing consisted of alternating between starting with the Squatbar/Olympic barbell.
Although the results are comprehensive and clearly shown, it is recommended that more information, such as the statistical significance value and effect size, be included in the tables.
The authors appreciate the perspective of the reviewer. However, we believe increasing non-significant information might reduce readability without providing extra value, as the highest non-significant p value and effect size is already presented in text. The effect size and p value of external shoulder rotation is already included in text, while all the other findings are null-findings.
Reviewer 3 Report
The 1-RM concept was not explained on the text.
Improve the description of the bars. Their mass, dimensions and shape (length and radius of curvature should be shown).
Rewrite “training for a meet”
Improve the description of the “large range of motion” concept.
Don´t use the term “Anecdotal”, it’s not a scientifical term.
Correct the typo “IBM Crop.”
Don´t start a new paragraph with “Nor were any significant …”
The “external rotation of the shoulders”, should be better explained. Is it good or bad to have a higher shoulder rotation ?
English is ok, only minor changes needed.
Author Response
The 1-RM concept was not explained on the text.
The authors believe the 1-RM concept is already described in the text: “The sport of powerlifting consists of the aforementioned three movements whereby the athlete seeks to lift as much weight as possible for one repetition (1-RM)”. However, a definition of the abbreviation is now also added to the abstract.
Improve the description of the bars. Their mass, dimensions and shape (length and radius of curvature should be shown).
The dimensions are now included.
Rewrite “training for a meet”
Revised to: “specific training prior to competition can become repetitive”
Improve the description of the “large range of motion” concept.
Sentence is now revised: “lifting with the joints towards their end range of motion.”
Don´t use the term “Anecdotal”, it’s not a scientifical term.
The authors believe anecdotal observations are very important in the realm of sport science, as they often lay the foundation for generating hypothesis. It is not uncommon that research stems from anecdotal observations. Furthermore, the following sentences states the importance of testing these anecdotes through the scientific method. However, we may revise this sentence if the reviewer feel it is necessary.
Correct the typo “IBM Crop.”
The typo is now corrected.
Don´t start a new paragraph with “Nor were any significant …”
Sentence has been revised.
The “external rotation of the shoulders”, should be better explained. Is it good or bad to have a higher shoulder rotation ?
It is neither “good nor bad”, however, some athletes may be compromised in their technical execution of the lift if they struggle with reduced mobility in their shoulders. The authors are of the opinion that this is addressed throughout the manuscript by the following sentences:
As performance in powerlifting is determined by 1-RM, athletes often perform the squat with a low-bar placement which for many athletes is beneficial [15, 16]. However, the back squat challenges shoulder mobility [17], especially when the bar is placed further down the spine in a low-bar squat
From an acute biomechanical perspective, squatting with a Squatbar® barbell may be an option to that with the Olympic barbell, which provides the same joint kinetics and kinematics and EMG, but requires less shoulder external rotation, which is beneficial for athletes with shoulder mobility issues.
As such, for an athlete suffering from reduced shoulder mobility, the Squatbar® is indicated from an acute biomechanical perspective to be a good alternative for accumulating training volume in a movement pattern with similar requirements to the traditional barbell back squat with an Olympic barbell.
The acute observations in EMG, kinetics and kinematics indicate as such the Squatbar® to be a suitable substitution to the Olympic barbell for athletes with reduced shoulder mobility when training to increase 1-RM strength in the parallel back squat.
If warranted by the reviewer, a sentence may be added to specifically address this.
Reviewer 4 Report
Research is a popular topic.
The benefits of Squatbar® should be emphasized.
The discussion should be developed. The positive aspects should be emphasized.
The similarity rate (ithenticate) should be reduced (32%).
The t-value and the p-value should be shown in table Line 172 and line 177.
How was the sample group determined? Should do power analysis.
Which method was used when placing the EMG electrodes? (Seniam).
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Author Response
Research is a popular topic.
Thank you
The benefits of Squatbar® should be emphasized.
We have in the introduction written what the advantages are of using the Squatbar and hope these are enough, because there are not many other advantages we could think of, besides the shoulder kinematics.
The discussion should be developed. The positive aspects should be emphasized.
The suggesting of the reviewer is good. However, there are not many differences between the two barbells, which makes it very difficult toe emphasize the positive effects, when only the external shoulder is different. We think that we have emphasized that effect clearly in the text
The similarity rate (ithenticate) should be reduced (32%).
We don’t know what similarity rate the reviewer is talking about, as we have written it from scratch and have no clue about what of the text is similar to other studies.
The t-value and the p-value should be shown in table Line 172 and line 177.
The authors appreciate the perspective of the reviewer. However, we believe increasing non-significant information might reduce readability without providing extra value, as the highest non-significant p value and t-value is already presented in text. The t-value and p value of external shoulder rotation is already included in text, while all the other findings are null findings.
How was the sample group determined? Should do power analysis.
We have based our sample size upon earlier studies in squats (variability within subject on kinematics and kinetics and EMG) and performed a sample size calculation. This was now mentioned in the text:
Based upon earlier studies in squats, the minimum number of participants required was estimated by using G*Power 1 (version 3.1.9.6). The analysis indicated that at least 10 participants (α = 0.05, 1−β = 0.95, Cohen’s d = 1.2) were necessary.
Which method was used when placing the EMG electrodes? (Seniam).
The SENIAM method of placing the EMG electrodes is now included under 2.3. Measurements.
Reviewer 5 Report
Please add a conclusion in the abstract part.
Lines 38-40: “The knee, shoulder and lower back are the body regions where injuries are most frequently reported.” The reviewer agrees with the author’s opinion about this, which is also common among volleyball players and runners. Perhaps the authors can refer to the follow research literature to further verify the opinion: (1) Explaining the differences of gait patterns between high and low-mileage runners with machine learning (10.1038/s41598-022-07054-1); (2) Single-Leg Landings Following a Volleyball Spike May Increase the Risk of Anterior Cruciate Ligament Injury More Than Landing on Both-Legs (DOI: 10.3390/app11010130); (3) Temporal kinematic and kinetics differences throughout different landing ways following volleyball spike shots (DOI: 10.1177/17543371211009485)
Please further clarify what is strength-trained men, it is necessary to tell how many years that they trained or what kind of level they are.
Did you calculate how many samples that you need to include in this study?
Please further clarify where is the placement of reflective marks.
Lines 132-133: Please add a citation here, and explain how to exported data to the Visual 3D.
Which model you used?
It is better if the author can provide an image of the EMG sensor placement.
Author Response
Please add a conclusion in the abstract part.
A conclusion is now added in the abstract.
Lines 38-40: “The knee, shoulder and lower back are the body regions where injuries are most frequently reported.” The reviewer agrees with the author’s opinion about this, which is also common among volleyball players and runners. Perhaps the authors can refer to the follow research literature to further verify the opinion: (1) Explaining the differences of gait patterns between high and low-mileage runners with machine learning (10.1038/s41598-022-07054-1); (2) Single-Leg Landings Following a Volleyball Spike May Increase the Risk of Anterior Cruciate Ligament Injury More Than Landing on Both-Legs (DOI: 10.3390/app11010130); (3) Temporal kinematic and kinetics differences throughout different landing ways following volleyball spike shots (DOI: 10.1177/17543371211009485)
Reference (1) and (3) has now been added in support for the evidence of injury across multiple sports.
Please further clarify what is strength-trained men, it is necessary to tell how many years that they trained or what kind of level they are.
Sentence is now revised to emphasize that the men were recreationally strength trained.
Did you calculate how many samples that you need to include in this study?
We have based our sample size upon earlier studies in squats (variability within subject on kinematics and kinetics and EMG) and performed a sample size calculation. This was now mentioned in the text:
Based upon earlier studies in squats, the minimum number of participants required was estimated by using G*Power 1 (version 3.1.9.6). The analysis indicated that at least 10 participants (α = 0.05, 1−β = 0.95, Cohen’s d = 1.2) were necessary.
Please further clarify where is the placement of reflective marks.
Placement of the reflective markers have now been included.
Lines 132-133: Please add a citation here, and explain how to exported data to the Visual 3D.
The sentence now includes a reference, and that the data were converted to C3D files and exported to Visual 3D.
Which model you used?
We don’t know exactly what is meant with which model that was used. If it is about the how we build our segments, it used the markers we had attached to the subject (very segment had at least 3 markers), which was the basis for the whole skeletal model. The marker set up was not according to a specific model, but based upon similar previous studies on squats. The marker placements are included to the text now and we hope this gives enough information.
It is better if the author can provide an image of the EMG sensor placement.
The authors believe placement is already thoroughly described, however, an image can be provided if the reviewer think it is necessitated.
Round 2
Reviewer 2 Report
Congratulations
Author Response
Thank you
