Comparative Biomechanical Analysis of the Hurdle Clearance Technique of Colin Jackson and Dayron Robles: Key Studies
Round 1
Reviewer 1 Report
General Comments:
This paper describes a detailed and systematic analysis of a single hurdle clearance by two of the most accomplished high hurdlers in history, and the results of those technical analyses will be of great interest to coaches and athletes. Two-dimensional video analysis is appropriate for this type of technical analysis and the process has been carried out logically, although a more detailed description of some steps would be useful (as noted below).
I find the comparisons between the two data sets problematic, however, for a number of reasons: (a) there is only one clearance per person and we do not know how representative that is; (b) we do not know what had happened earlier in the race – for the athlete being analysed and/or his competitors – that may have affected the clearance at the fifth hurdle; (c) the trial for Colin Jackson is substantially slower than his personal best and so likely does not represent “optimal” technique for him; and (d) there are differences in the methodology used for the two data collections. At present, these limitations are restricting the conclusions that can be usefully drawn from the paper.
Specific Comments:
Introduction:
Line 37: A comma has been used in place of a decimal point here, and at many other points in the paper. See Table 2, for example.
Line 46: I am not sure that “biomechanically rational” is the correct phrase here, or elsewhere. “Biomechanically effective”, perhaps.
Line 52ff: Very lengthy background for the elite level of these two athletes is given here, with some repetition around line 76. I think it would be enough to say both were world record holders, with their personal bests in Table 1.
Line 71: Is it agreed that these are the two athletes who have set the highest standards in hurdle clearance, or was their success partly due to sprinting speed? It might be advisable to replace “the two athletes” by “two athletes”.
The review of literature in this section could be usefully expanded, to provide more context for the populations studied and the key parameters identified in previous research on hurdling.
Methods:
Line 83: The mention of “fourth and fifth” hurdles here is not consistent with the rest of the paper. (See also Line 104: “the segment between hurdles 4 and 5”).
Sections 2.3 and 2.4: The description for Section 2.3 is, in general, less complete than Section 2.4, lacking mention of calibration procedures etc. The shutter speed is not identified for either. Why have different models been used to determine the COM (or “centre of gravity” in Line 106) in the two cases?
Line 116: Please check the camera model: the specifications for the EX-F1 do not show an option for 100 Hz (720 x 576 pixels) in HS Mode.
Results:
Line 124: “weight” should be “mass” here, and in Table 1.
Line 126: How are you defining “body slenderness”? This value is not reported in Table 1.
Line 128: There are two typographical errors in this line, and a careful review of the spelling is required for the whole manuscript.
Line 143: I would not report coordinates to 0.001 m with manually-digitised, video-based analysis.
Figure 1: There are clear issues with scaling in this figure, and the inconsistency in formatting suggests that the two sub-figures may have been created for other purposes and then copied here. If the hurdle heights are scaled to be the same then the peak height of the COM for Robles (reported to be 0.32 m above the hurdle) is actually clearly higher than that for Jackson (supposedly 0.45 m above the hurdle). This makes it hard to trust the other values mentioned, and I would recommend a careful review of all the results presented. Were there calibration issues, calculation issues and/or plotting issues?
Discussion:
In general this section contains some interesting comparisons and suggestions, but it is very descriptive in nature. The reasons why one particular outcome for each variable is more biomechanically “rational” need to be explored further (especially when, as you have identified, the anthropometrics of the two athletes are quite different).
Line 153ff: The reference to Amara’s work seemingly also refers to a single hurdle clearance by one athlete, and therefore has the same limitations mentioned above for the two analyses undertaken in the current study.
Line 185: How is “take-off angle” defined?
Conclusions & Practical Applications:
Again, these sections are of potential interest and value to researchers, coaches and athletes, but that usefulness would be greatly strengthened by a more extensive data set and by more explanation of the biomechanical principles underpinning the statements made about technique.
Line 221: While 50 Hz 2D video analysis is understandable, given when and where the data were collected, it would not now be considered “modern diagnostic technology”.
Line 230: Following all of the differences you have reported earlier, the conclusion that “the differences in kinematic parameters are minimal” appears strange and hard to justify.
Author Response
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Author Response File: 
Author Response.pdf
Reviewer 2 Report
The summary should clearly include information from the different sections (introduction, objective, method, results and conclusions).
The section on participants should be explained more clearly, and also the selection procedure. They should also include the type of study in question. Finally, a data analysis and design section should be included.
There are aspects in the discussion such as the figures that I think should be in the results section.
Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report
Dear authors, first of all, I would like to thank you for your collaboration by sending your manuscript to this journal, as I consider it to be interesting for the readers. Next, I suggest some recommendations to improve the quality of your study.
Introduction
This section is too short, I recommend that you expand it. Similarly, in this section most of the quotes are very old, it is recommended to update quotes and look for others that support the study problem.
Results
According to table 1, a footnote should be made specifying any acronyms used, in this case (BMI).
Bibliographic references.
They should be checked because they do not comply with the Vancouver standard, mistakes have been made. For example, in reference 12, the year of publication is not in its corresponding place.
Author Response
Please see the attachment
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
General Comments:
I would like to thank the authors for their detailed and systematic responses to the issues that I raised. Some helpful clarifications and corrections have been made, and the paper has been improved by those changes.
I still think that the paper would benefit from revisions to the Introduction and Discussion, and I remain unconvinced by your arguments for drawing such strong conclusions from the comparison between two single hurdle clearances. My comment about what happened earlier in the race related to the fact that one of the athletes may have clipped the previous hurdle, or may have had the athlete in the next lane moving close to his lane etc. I do not believe you should call this an “experiment” (lines 80 and 246) and I would be more cautious with the use of the word “optimal”. However, I acknowledge that you have now described this work as a case study.
The revisions include a number of additional errors (see below) and I would recommend a further careful check of the manuscript. There are, for example, still some commas as the decimal marker in Table 2.
Specific Comments:
Line 125: I assume you mean 300 fps rather than 3300 fps, and “downsampled”.
Line 138: As in my previous comments this should be “mass” rather than “weight”, and I would refer to “Body Mass Index” in this sentence. BMI can only provide a rough estimate of body fat.
Table 1: The BMI value for Robles appears to be incorrect; it should be 21.43 from the height and mass presented.
Line 191: “tip of the foot”?
Line 241: It is not clear what you mean by this sentence, and I am not sure how it can follow from sentences highlighting the differences in those kinematic parameters. What do you mean by “depend”? If it is simply that the parameters of projectile motion are important then that is true for all hurdlers. I would not call any athlete’s technique “optimal”, as that implies it cannot be improved, and that is certainly not the case for Jackson’s performance here. There are spelling mistakes with “clearance” and “clear”.
Author Response
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Author Response File: 
Author Response.docx
Reviewer 2 Report
Thank you for attending my suggestions and explaining the issues.
Author Response
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Author Response File: Author Response.docx
