Fat-Free Mass Normalization Impacts Cardiorespiratory Fitness in Overweight Adolescents

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This manuscript was written quite well. However, please clarify more as follows.

1. Line 45: “Fat-free mass (FFM), which includes LBM minus essential fat”. This sentence is incorrect. Please clarify it.
2. Please add hypothesis and main objective.
3. Lines 48-50 seem to mention on submaximal markers. “Submaximal markers such as VO2AerT, VO2AnT which are frequently used due to challenges in eliciting maximal effort [12]. These submaximal indicators reflect metabolic efficiency and endurance capacity and are reliable proxies of CRF [3,12–14].” However, as I understand VO2AerT, VO2AnT were measured during the maximal test. Moreover, the objective, hypothesis, discussion, and conclusion did not emphasize them.” Please clarify this point.
4. How the authors calculate sample size.
5. No method explains how to measure the difference in the slope of all gas variables.
6. In line 113, SPSS Software, IBM version 29.0.1 please add city and country.
7. In Figure 1, no VO2peak was shown.
8. In Figure 1 and 2, authors should write the same pattern of all legends.
9. In Table 1, FM% (%) and FFM% (%) keep % only in bracket
10. Please write the contents in Table 1, Table 2, and supplementary Tables in the maintext.
11. Gas exchange Parameters in Table 2 seems to be incorrect. Please clarify.

“Gas exchange is the process where oxygen moves from the lungs into the bloodstream, and carbon dioxide moves from the blood to the lungs. (Powers and Dhamoon 2023)”

(Powers KA, Dhamoon AS. Physiology, Pulmonary Ventilation and Perfusion. [Updated 2023 Jan 23]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK539907/)

12. In Line 204: Psychologically, FFM-based normalization can serve as an important motivational tool for children.

According to The World Health Organization (WHO) that defines an adolescent as any person between ages 10 and 19. Please clarify it.

13. In case of BM- and FFM-based normalization, the authors should discuss more on the ability of muscle fibers of NW and OW.
14. In supplementary file, there should be unit of all variables.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

This manuscript addresses an important and timely issue—the accurate assessment of cardiorespiratory fitness (CRF) in adolescents, particularly in relation to body composition differences between normal-weight and overweight groups. The study is well-structured and presents valuable data; however, several aspects require clarification or refinement to strengthen the manuscript's clarity, readability, and scientific rigor.

Point-by-Point Comments

1. Title and language quality: The title is clear and relevant. However, simplifying the title slightly may improve its impact and accessibility to a broader audience. While the manuscript communicates the central ideas well, the English language requires revision in several places to correct grammatical errors and improve sentence flow. Professional English editing is recommended to enhance overall quality.
2. Abstract: The abstract would benefit from a clearer opening sentence that introduces the relevance of the topic—specifically, the importance of accurate CRF assessment in adolescents and the limitations of using body mass alone for VO₂ normalization.
3. Abstract – Interpretation of Results: There is some ambiguity in the abstract when discussing the results normalized by FFM. While the group comparison reportedly shows no significant difference, the authors highlight strong correlations and slope variations involving FFM. Please clarify whether these findings are complementary or contradictory, and consider breaking this section into clearer, logically connected statements.
4. Formatting of statistical terms: Ensure that all statistical notations (e.g., p) are italicized to comply with MDPI style guidelines.
5. Terminology consistency: Please clarify and consistently use either "VO₂max" or "VO₂peak" unless both are clearly defined and used for distinct purposes within the manuscript.
6. The manuscript uses both “lean body mass (LBM)” and “fat-free mass (FFM).” While the difference is explained, consider clarifying early in the introduction that FFM excludes essential fat and explaining why this distinction is particularly relevant to the current study.
7. Participant controls: It is commendable that the testing time was standardized. However, consider adding whether participants’ diet, hydration status, or physical activity prior to testing were controlled or recorded, as these can influence VO₂ outcomes. Also, clarify how missing data (if any) were addressed in the statistical analysis.
8. Sentence structure and readability: Several sentences are lengthy and may affect readability. Breaking complex ideas into shorter, clearer sentences would improve flow. For instance, the sentence starting with “LBM offers a precise estimate…” could be revised for clarity and conciseness.
9. Figures and statistical annotations: The inclusion of correlation values and slope differences is valuable. However, figure captions should expand all abbreviations and clarify statistical markers. Please also report exact p-values for all relevant correlations to enhance transparency.
10. Data accuracy: While statistical results are generally well-reported, there appear to be inconsistencies in Table 2. For example, the VO₂AerT value for the overweight group (reported as 11178 ± 258 mL/min) seems unusually high and should be verified.
11. Clarification of findings: The relationship between group comparisons and correlation/slope analyses requires clarification. The manuscript reports no significant group difference in VO₂ normalized by FFM but highlights strong associations and differing slopes. Please clarify how these findings align and what they suggest about FFM as a normalization factor.
12. Ethics statement: Please include a complete ethics statement confirming that the study received approval from an appropriate institutional review board or ethics committee.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

Dear Authors,

I commend you for addressing the important issue of assessing cardiorespiratory fitness in adolescents. Manuscript ID "Adolescents-3710184" suggests that fat-free mass (FFM) normalization is a more precise alternative to body mass (BM) normalization when measuring VO₂ in overweight youth. This is a physiologically and clinically relevant approach. However, the manuscript requires substantial revisions to the methodology, formatting, and presentation of the results.

First, the study design is not explicitly stated. Based on the methods and objectives, it appears to be a cross-sectional observational analytical study; however, this is not mentioned in the manuscript. This omission limits the reader's understanding and undermines the scientific framing. Adherence to key STROBE items is therefore recommended, particularly concerning the study setting, sampling procedures, and measurement techniques.

The methods section is overly concise and omits essential details, such as the sampling strategy, the assessment conditions for body composition via BOD POD, and the ethical considerations beyond the IRB number. Additionally, there is no justification for the sample size or power calculation, which is crucial given the small group size (n = 19). The statistical analysis lacks effect size measures and p-values for correlation coefficients, both of which are necessary for interpretation.

In terms of formatting, the manuscript does not comply with the Adolescents template. There are improper uses of bold font throughout the text, inconsistencies in figure typography, and layout issues (e.g., line 135 appears isolated). Tables 1 and 2 are not referenced in the Results section, and their findings are not discussed in the narrative. These formatting issues must be addressed to improve clarity and readability.

SPECIFIC COMMENTS
I. Study Design: Please define the study as a cross-sectional, observational design. This classification is essential for understanding the methods and results in context.

II. STROBE Reporting: Consider adopting relevant items from the STROBE checklist for cross-sectional studies, particularly those related to the setting, sampling, and handling of variables.

III. Methods Detail:
III 1. Add inclusion/exclusion criteria.
III 2. Clarify the sampling technique and recruitment context.
III 3. Describe BOD POD procedures, including fasting, calibration, protocol, attire, etc.

IV. Sample Size Justification: Provide an estimation of statistical power or a rationale for the group size used.

V. Statistical Reporting:
V 1. Include effect sizes (e.g., Cohen's d or η²) for all between-group comparisons.
V 2. Provide p-values for the correlation coefficients reported on lines 128–134.
V 3. Confirm that the assumptions for ANOVA were verified.

VI. Formatting and Template:
VI 1. The manuscript does not follow the Adolescents template. Please adapt it accordingly.
VI 2. Avoid bold fonts unless required.
VI 3. Ensure that the typography of figures matches that of the manuscript.
VI 4. Address the layout issue on line 135 (orphaned line).

VII. Tables and Figures:
VII 1. References to Tables 1 and 2 should be included in the Results section before introducing figures.
VII 2. Discuss the descriptive characteristics in Table 1 in the text to provide proper context.
VII 3. Reorganize the section so that it follows a logical flow: first, descriptive; then, comparative; and finally, correlations.

VIII. Ethical Details: Include details about consent, assent, and the institution beyond the IRB number.

In conclusion, I recommend a major revision contingent on the following: a full methodological expansion; improved reporting according to the STROBE guidelines; inclusion of missing statistical details; and full adherence to the journal's formatting guidelines.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

Comments and Suggestions for Authors

Dear Authors,

I have had the opportunity to review the second version of your manuscript, "Fat-Free Mass Normalization Impacts Cardiorespiratory Fitness in Overweight Adolescents" (ID: Adolescents-3710184). I would like to express my gratitude for their thorough and effective revisions.

It seems that every concern I had raised in my initial review has been addressed, and the manuscript has been transformed into a methodologically sound, well-structured, and clearly written paper. Your diligent work has made a significant contribution to the field.

I have no further requests at this time and would be happy to recommend this manuscript for publication.