The Magical Horizontal Force Muscle? A Preliminary Study Examining the “Force-Vector” Theory
Round 1
Reviewer 1 Report
This is a very interesting and topical article, which provides evidence regarding some interesting and important concepts. The manuscript is well written, although some additional literature regarding the hip thrust could be included within the Introduction and referred back to in the discussion. In addition, some discussion regarding the measurement error of the jump testing methods used should be included and mentioned as a potential limitation within the discussion section.
Specific Comments
Lines 18-19: Exact p values and Hedges g effect sizes should be included here
Line 38: Please be specific and add examples of the ‘athletic skills’
Line 40: Please be specific and add examples of the ‘performance measures’
Lines 47-50: Please explore the fact that the hip thrust results in predominantly vertical ground reaction forces and relate to the information regarding the global and local coordinate frames.
Line 53: Change ‘don’t’ to ‘do not’
Line 92: Please reword this sentence, consider: ‘A repeated measures within subject design was used for this training study, with no control group’
Line 122: Delete, ‘There were…’ and add ‘were’ after parentheses
Lines 122-129: How did you ensure that there was no countermovement and what happened when a countermovement was observed when it was not required?
Lines 156: How was a consistent range of motion determined, was this measured?
Lines 173-176: Please add ICC and %CV for the jump trials and add Hedges g effect size calculations for the pre-post changes, including appropriate scales for the interpretation of the resulting values.
Lines 176-179: Please explain this in a little more detail
Line 271-271: Check the reference for reference 6.
Author Response
Response document uploaded.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Interesting topic and quite important for coaches.
Comments:
the title sounds more like a review - suggest removing he first sentence. Also - this appears to be a preliminary study and this should be reflected in the title
major problem: Table 4 - most of these values - especially the vertical jump with and without countermovement do not appear to be correct - indeed, the two VJ's have exactly the same pre-post means and SD's but different % changes??
Major Problem: No reliability measures are presented?
Should calculate effect sizes - this might help strengthen your case
You need to better justify the training protocol and the use of a 3 RM instead of 1 RM
Specifics
Lines 63 -64: you might support this contention better - take a look at (particularly the last one):
Weyand, P.G et al. Faster top running speeds are achieved with greater ground forces not more rapid leg movements.
J Appl Physiol 89: 1991–1999, 2000.
Weyand PG, et al. . The biological limits to running speed are imposed from the ground up. J Appl Physiol 108: 950–961, 2010. First published January 21, 2010
Biewener A.A et al. Scaling body support in mammals:Limb Posture and muscle mechanics
Science 245(4913):45-8, 1989
Chang Y-H et al. The independent effects of gravity and inertia on running mechanics.
Journal of Experimental Biology 203(Pt 2):229-238, 2000
Line 97; Subjects - should be called athletes - need much more information here. were they competitive athletes, what level? - how long had they been training (all that is given is a minimum 1 year threshold) , what was their strength training background?
Line 123--- was there an arm swing allowed? also these are quite basic, though very particle) measures - another reason to term this study preliminary
line 173 - version of stats package?
Line 229-245 - not quite following this - there are a number of reasons why Contreras et al may have gotten the results they did - however, it does make some sense to train a number of different hip angles - can you present evidence that squats of weightlifting movements don't do this?
Practical application - while your results do "suggest" that the hip thrust might be useful - However, as you had no control group or comparison group - this should be pointed out as a major limitation it providing information to coaches about exercise selection.
Author Response
Response uploaded as a Word file.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Jump values in table 5 should only be reported to 2 decimal places, as the measurement technique is not precise enough for 3 decimal places.
Line 269: Change 'don't' to 'do not'
Author Response
Jump values in table 5 should only be reported to 2 decimal places,
as the measurement technique is not precise enough for 3 decimal places.
Adjusted accordingly.
Line 269: Change 'don't' to 'do not'
Adjusted accordingly.
Reviewer 2 Report
line 147: Hip thrust performance was evaluated by testing 3RM as previous authors have suggested that this is safer than evaluating the 1RM [7]. This statement appears to be the authors opinion rather than based on evidence. Several presentation I have seen plus many opinions of experience researchers and strength coaches indicated the opposite - indeed it is possible that trying to grind out one more rep is more injurious than performing a 1 RM (which has a low injury rate) Probably need to come up with additional reasons
Throughout the manuscript including figures. the use of the term significant is not quite used correctly as this should refer to statistical aspect such as "statistical significant"
Author Response
Line 147: Hip thrust performance was evaluated by testing 3RM as previous authors have suggested that this is safer than evaluating the 1RM [7]. This statement appears to be the authors opinion rather than based on evidence. Several presentation I have seen plus many opinions of experience researchers and strength coaches indicated the opposite - indeed it is possible that trying to grind out one more rep is more injurious than performing a 1 RM (which has a low injury rate) Probably need to come up with additional reasons
Thank you. We have clarified this in the manuscript, added an additional reason, and stated that the safety concern was the authors' opinion.
"Hip thrust performance was evaluated by testing 3RM as this measure was used in a previous study that evaluated the effect of a hip thrust training programme thus facilitating a more direct comparison [7]. The authors of the previous study [7] cited safety concerns as their reason for preferring 3RM over 1RM testing."
Throughout the manuscript including figures. the use of the term significant is not quite used correctly as this should refer to statistical aspect such as "statistical significant"
We have read through the manuscript carefully and have corrected the text to specify "statistical" significance. For example:
"The athletes’ improvement in hip thrust performance was statistically significant (33.0%, p < 0.001, η2 = 0.784; Table 5). Similarly, there was a statistically significant improvement in all measures of jump performance (time effect – p = 0.004, η2 = 0.585), but there was no statistically significant difference in the improvement in vertical or horizontal jump performance (time × jump task effect – p = 0.561, η2 = 0.035)."
