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Many thanks for addressing the previous comments. The article is now acceptable.
One minor issue in the abstract, background section, line 4 'may influence of level of...' delete 1st 'of' - this should be fixed while in production,
The article is clear and well-written. Reviewer 1 suggests removing the prediction equations. I agree. If you feel they should remain, the statistical section should be expanded to include the criteria for selecting univariate predictors for inclusion in the model and criteria used to select variables to add or drop at each step of the model. However, with only 50 participants, the statistical power is very low and the model is of doubtful generalizability. It would be better to remove it.
The participants were randomly assigned to measurements in various orders...how was the randomisation conducted?
The participants were young...tourniquet occlusion in clinical practice is often used in much older patients. Should be mentioned as a limitation.
There are a few minor points:
Abstract
Line 6‘may influence THE level of occlusion…’
Line 10 ‘5 minUTES…’
Material and methods
Line 75: 24 hOURS
Line 83: participants’ not participant’s
Line 111: ‘or’ instead of ‘nor’
Discussion
Line 186: ‘in A seated…’
Line 230: should ‘venous’ be ‘arterial’?
See general comments
See general comments
See general comments
The authors present data on a topic that is of great methodological importance. This study is straight forward and will be of interest to those implementing blood flow restriction in research and/or clinical settings. I do, however, have comments that I think will improve the manuscript. My major criticism is there “prediction” equations. I recommend removing them from the manuscript as the important data lies in the change in position. I believe the regression model assumes that the data is normally distributed, which they state it is not. More importantly, however, is that I do not think the model is stable with such a small sample size. General rules of thumb suggest around 40 people per predictor. You have multiple predictors but only have 50 individuals. Specific comments below:
Line 51: systolic blood pressure is only a meaningful predictor in the upper body, but the size of the limb is always explaining more variance than any other predictor. This should be corrected.
Line 85: what was the size of the blood pressure cuff?
Line 88: extra period at the end of this sentences
Line 89: it seems more appropriate to just say “skinfold thickness” given that’s what you’re actually measuring.
Line 111: what is the confidence interval around that 0.08?
Line 154: might be useful to add in the variability of the differences into the results
Line 190-203: I feel like this is pretty redundant and could probably be cut down quite a bit
Line 213-214: having references after each one of those suggests that those references demonstrates ischemic reperfusion injury, nerve injury, etc. Perhaps just state that those things have been speculated in those papers?
Line 217: I think the Jessee and Mattocks paper measured discomfort…not pain per se
Line 220: Martin Hernandez reference would seemingly suggest that volume is only important to a point…not sure that reference really corroborates that sentence completely…consider revising
Line 224: what is a light load?
Line 229: should this say “in a seated…”
Line 231: could someone argue that there is only minimal pressure needed to restrict venous return? I see an argument for manipulating arterial in flow and how that could impact metabolites…but I think this should be made a bit more clear here
Line 225: might be useful to discuss the Ingram et al. investigation…it seems as though that is related to reliability of AOP…and along those lines…how do you separate measurement error from biological variability of blood pressure?
https://www.ncbi.nlm.nih.gov/pubmed/28131507
Line 277: I would remove this entire section
Line 303: how do we know this measurement is “accurate” based on this current study?
Line 308: how much does this measurement actually change? Maybe you only need to measure it once and use that pressure for all subsequent visits? Would it have to change a decent amount before it meaningfully impacted applied pressure?
Line 317: is there a need to include the company name in the conclusion? Here and throughout the manuscript (outside of the methods)…it might be better to describe it without promoting a product.
The paper is well written and easy to follow.
If the cuff was placed at the most proximal part of the leg, why was leg circumference and fat thickness measured at the midway point of the leg? Was this measure located under the cuff for most individuals?
I applaud the authors for repeating the 3 measures on a second visit, but I question why the same order that was performed in visit one was not replicated in visit 2. If there is indeed an order effect, then you have added additional error above biological variability/measurement error that can simply be attributed to changing the order.
I applaud the authors for repeating the 3 measures on a second visit, but I question why the same order that was performed in visit one was not replicated in visit 2. If there is indeed an order effect, then you have added additional error above biological variability/measurement error that can simply be attributed to changing the order.
To generate prediction equations, what variables were entered into the model in the first place? You mention that only those that were significant predictors were included in the prediction equation, but which were initially entered? This information should be added.
In the reliability section the only comparison that should be made here is the AOP measured with the Delfi cuff and the AOP measured with the dopplar ultrasound. A comparison of AOP with the Delfi cuff to FMD or MBV measured using ultrasound is not appropriate as these are much more difficult measures and thus will have greater error. If the Delfi cuff could measure FMD or MBV this would be a fair comparison, but only studies using techniques to measure AOP should be compared here. After all, it would presumably be much easier to repeatedly detect the cessation of blood flow than to repeatedly quantify the velocity of blood flow.
Discussion
Line 223: “However, current literature suggests that light-load BFRE training protocols benefit from higher occlusion pressures (80% vs 40%) (Lixandrão et al., 2015), which would support the importance of accurate AOP measurement for prescription of relative pressures.” Another study found no differences between 40% and 90% but this study used 30% 1RM instead of 20% 1RM. Regardless, this study should also be mentioned if this previous study is mentioned
https://www.ncbi.nlm.nih.gov/m/pubmed/26137897/.
The authors compare the necessary occlusive pressure to cease blood flow in three different body positions. Overall, the manuscript is well written and straightforward. Comments are attached.
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