PONE-D-24-07083Dileucine Ingestion, but not Leucine, Increases Lower Body Strength and Performance Following Resistance Training: A Double-Blind, Randomized, Placebo-Controlled TrialPLOS ONE

Dear Dr. Kerksick,

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PLOS ONE

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2. We noticed you have some minor occurrence of overlapping text with the following previous publication(s), which needs to be addressed:

https://doi.org/10.1186/s12970-020-00394-1

https://doi.org/10.1016/j.isci.2023.108643

In your revision ensure you cite all your sources (including your own works), and quote or rephrase any duplicated text outside the methods section. Further consideration is dependent on these concerns being addressed.

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4. Thank you for stating the following financial disclosure: 

 [Funding was acquired by CMK. Grant #: 01-2020. This study was funded by Ingenious Ingredients, LLC (https://ing2.com/). Martin Purpura and Ralf Jager are principals of Ingenious Ingredients, LLC,  the sponsor of the study, and  were involved in conceptualizing and designing the study, and reviewing and editing the manuscript but were not involved in data collection or data analysis.].  

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[I have read the journal's policy and the authors of this manuscript have the following competing interests: M.P and R.J are principals of Ingenious Ingredients, LLC, the sponsor of the study, and inventors of numerous patent applications for the use of dileucine but have not been involved in data collection or analysis. All other authors declare no competing interests.]. 

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Reviewers' comments:

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Comments to the Author

1. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

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2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

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3. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

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PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

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5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: A randomized controlled clinical trial was conducted which aimed to assess the effects of DILEU supplementation on resistance training adaptations. DILEU supplementation enhanced lower body strength and muscular endurance in resistance-trained males more effectively than LEU or PLA.

Minor revisions:

1- Line 100: State the statistical testing method that achieves 80% power.

2- If the interaction effect is significant, provide an interpretation of the results, but do not test main effects because the tests for main effects are uninteresting in light of significant interactions. If interaction effects are non-significant, drop the interaction effects from the model and test the main effects. Determining which results to present when testing interactions is often a multi-step process.

Reviewer #2: line 217: workload greater than 7.5% often produce greater Wingate results. Why did you choose 7.5%?

line 222: ??? Participants ramped up rpm following when resistance applied?. Typically, rpm are maximized with no load and once maximized the workload is engaged. Your approach would likely generate less than maximal values.

line 226: What about the fatigue index?

line 263: Often supplements do not contain the quantity of compounds claimed or contain others not listed on the label. Please indicate the analyzed supplement contents or list as a limitation.

line 295: ....endpoints of ....

TABLE 2. Weight should be mass

Relative bench of leg press ??? you need to xplain what this is and add units

line 318: Seems to be be methods not results

line 334: No change in muscle thickness with training? Does this indicate the training stimulus was inadequate? Please discuss.

line 372. Why only males?

line 441 and elsewhere. kcal/kg/d is mathematically incorrect. Should be kcal . kg-1 . d -1 (dots should be raised to the centre of line and -1 written as superscripts) Sorry the review pane doesn't allow me to write correctly.

Figures: Use open and closed symbols as well as differing shapes symbols as this makes results more clear.

Reviewer #3: [1] P3 L45: If the outcome of the study is performance, the authors should not mention health and ageing in the introduction. It is also important to explain how MPS could affect performance.

[2] P3 L56:  Please indicate some sources of protein with higher leucine content.

[3] The third paragraph is longer than expected, and the mechanisms are very detailed in the introduction section. Please summarize the main ideas.

[4] P4 L90: Why do the authors choose ten weeks? This should be explained in the introduction – the chronic effects of amino acids – using relevant literature.

[5] P5 L94: Why do the authors randomized based on fat-free mass when the main outcomes were performance?

[6] P5 L104: The sentence about body composition needs to be clarified. Please rephrase.

[7] P11 L249: Why do the authors use the Harris-Benedict equation?

[8] P14 Table 2: Please add the t and p values to the table.

[9] P17 Table 4: Please adjust Table 4. It is not presentable.

[10] P17 L39: Please summarize the direction of the differences.  

[11] The discussion is well written. Congratulations.

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Reviewer #1: No

Reviewer #2: Yes: Peter WR Lemon

Reviewer #3: No

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PONE-D-24-07083R1Dileucine Ingestion, but not Leucine, Increases Lower Body Strength and Performance Following Resistance Training: A Double-Blind, Randomized, Placebo-Controlled Trial

PLOS ONE

 Dear Dr. Kerksick,

Thank you for submitting your manuscript to PLOS ONE.

After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

==============================

COMMENTS:

1. In the work, all unit entries (text, tables) have still not been corrected in accordance with the reviewer's comments - they should be unified everywhere, e.g. "kcal∙kg^-1" instead of "kcal/kg"; "W∙kg^-1" instead of "W/kg”, „g∙kg^-1∙day^-1” instead of „g/kg/day”, „kg∙m^-2” „kg/m²” etc.

1. Line 60 - insert a space between (6-8%) and [14,15].

1. line 70: first use - "DiLEU (DILEU)", - use the full name and abbreviations can be used in the rest of the text.

1. Line 258 – change „caloric” to „energy”.

1. Table 2 - The lack of statistical values ​​makes it impossible to assess whether the participans did not differ "at the entrance" to the individual groups (LEU vs. DILEU vs. PLA). This point should be addedd so as not to leave readers with potential doubts.

1. Table 2 - In the unit description for Relative Leg/Bench Press, put "Body Mass" in the subscript.

1. Table 3 – insert „intake” after „Relative Energy”.

1. Table 4 – insert „mass” after "Dry lean".

1. In the revised description of the results, there are probably mistakes in some points - these descriptions do not match the data from the tables.

- In the line 359 - the authors write "a significant increase in bench press 1RM for DILEU compared to PLA (p = 0.02; 95% CI: 6.8, 75.9 kg)" - here it should rather be "total strength" (see table 5).

- in the 374 - similarly as above. Authors write „…increase in leg press RFT” - and it should be " …increase in total reps..".

- The whole manuscript should be checked in this respect to make sure all descriptions are correct.

1. Lines 383 and 384 - p values ​​are incorrect and there is an error in the descriptions („p = 0.0.54”;  „p = 0.0.65” and „p = 0.0.92”). This should be corrected and the entire text/tables/figures should be checked again.

1. Line – „calories” are not consumed - it is de facto a unit. Please correct the sentence and use "energy intake".

==============================

Please submit your revised manuscript by Nov 11 2024 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

Please include the following items when submitting your revised manuscript:

• A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'.
• A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'.
• An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'.

If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter. Guidelines for resubmitting your figure files are available below the reviewer comments at the end of this letter.

If applicable, we recommend that you deposit your laboratory protocols in protocols.io to enhance the reproducibility of your results. Protocols.io assigns your protocol its own identifier (DOI) so that it can be cited independently in the future. For instructions see: https://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols. Additionally, PLOS ONE offers an option for publishing peer-reviewed Lab Protocol articles, which describe protocols hosted on protocols.io. Read more information on sharing protocols at https://plos.org/protocols?utm_medium=editorial-email&utm_source=authorletters&utm_campaign=protocols.

We look forward to receiving your revised manuscript.

Kind regards,

Krzysztof Durkalec-Michalski, Ph.D

Academic Editor

PLOS ONE

Journal Requirements:

Please review your reference list to ensure that it is complete and correct. If you have cited papers that have been retracted, please include the rationale for doing so in the manuscript text, or remove these references and replace them with relevant current references. Any changes to the reference list should be mentioned in the rebuttal letter that accompanies your revised manuscript. If you need to cite a retracted article, indicate the article’s retracted status in the References list and also include a citation and full reference for the retraction notice.

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Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #1: All comments have been addressed

Reviewer #2: All comments have been addressed

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2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: (No Response)

Reviewer #2: Yes

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: (No Response)

Reviewer #2: Yes

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: (No Response)

Reviewer #2: Yes

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: (No Response)

Reviewer #2: Yes

**********

6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: (No Response)

Reviewer #2: There are still several places where the units are mathematically incorrect - see line 113 and elsewhere!

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Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #1: No

Reviewer #2: Yes: Pete Lemon

**********

[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.]

While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org. Please note that Supporting Information files do not need this step.

Dileucine Ingestion, but not Leucine, Increases Lower Body Strength and Performance Following Resistance Training: A Double-Blind, Randomized, Placebo-Controlled Trial

PONE-D-24-07083R2

Dear Dr. Kerksick,

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Kind regards,

Krzysztof Durkalec-Michalski, Ph.D

Academic Editor

PLOS ONE