Comparison of a Proposed Strength Training Program Using Indirect 1RM Versus Mobile Application Recommendations for Body Fat Loss: A Quasi-Experimental Study

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Dear Authors,

I am pleased to have had the opportunity to review your manuscript, which addresses a topic of great clinical and applied relevance: the prescription of strength training in individuals with obesity, with a particular focus on safety through the use of indirect methods for estimating maximal load and on the comparison between a supervised protocol and an approach based on a mobile application. The work presents elements of originality and interest, especially for its pragmatic approach and its attention to accessible intervention strategies.

However, in order for the manuscript to reach its full potential and be suitable for publication, I believe that several revisions are necessary, which I detail below.

Introduction
The introduction, although detailed, relies on a limited number of bibliographic references (only five). I suggest expanding the literature review to better contextualize the importance of a healthy lifestyle in counteracting overweight, obesity, and related diseases. In particular, it might be useful to cite the most recent World Health Organization (WHO) guidelines on physical activity. Furthermore, since nutrition plays a fundamental role in a healthy lifestyle, I recommend reading and citing the study by Ruggiero et al. (2026) Craft Non-Alcoholic and Low-Alcoholic Beer (NABLAB): Perceived Role as Functional Foods Among Italian Consumers and a Focus on Benefits for Well-Being and Physical Activity, which explores the perceived role of functional foods and their importance in the Mediterranean diet. Another relevant factor is sports practice; in this regard, you could cite, for example, the article by Montesano et al. (2019) Improvement in soccer learning and methodology for young athletes.

Materials and Methods
Group nomenclature. In the text, the groups are referred to inconsistently (e.g., experimental group A/B, control group). I invite you to choose a clear nomenclature and use it consistently throughout the manuscript. Since both groups undergo different interventions, I suggest opting for descriptive names such as "APP group" and "1RM group" (or similar), in order to make it immediately evident to the reader which group is being referred to.

Participant allocation. You do not specify how participants were divided into the two groups. I ask you to clarify the allocation method used.

Ethical considerations and informed consent. This section should be renumbered as subparagraph 2.2.

Line 95. Add the sentence that appears later in the text, indicating the institutional ethics committee with its reference number and date of approval: "The study protocol was approved by the corresponding institutional ethics committee."

From line 96 to 103 (including Tables 1 and 2). These contents should be moved to a new subsection of the Results, entitled "3.1 Population". I will discuss this later in the Results section.

Assessment of population parameters. Add a subparagraph (e.g., 2.3) to explain how all the population parameters under examination were obtained, indicating the instruments used (for example, for bioelectrical impedance analysis, specify brand and model).

Line 114. The reference to "figures 2, 3 and 4" appears to be a typo. Correct it.

Lines 127–130. I suggest avoiding bulleted lists. Integrate this information into a single body of text or present it in a table for better readability.

Rationale for Selection. This paragraph should be moved to the beginning of the section describing the APP, before explaining the features of the application.

Indirect Strength Assessment Protocol: The Brzycki Equation Method. This subsection should be placed immediately after the description of the training protocol for the 1RM group and before starting to discuss the APP.

Statistical analysis. Add a subparagraph dedicated to describing the statistical methods used.

Results
3.1 Population. As indicated above, I ask you to begin the Results section with a subparagraph "3.1 Population" that presents the pre- and post-intervention characteristics in close proximity, allowing the reader a direct comparison. In practice, combine Table 1 with Table 4 and Table 2 with Table 5.

Table 5. In many cases, the p-values are reported with an extra zero (e.g., 0.00002). Modify them to standardize them with the rest of the text, for example by using "<0.001" where appropriate.

Table 6. It is unclear whether the reported variations were assessed using specific instrumentation or whether they simply represent the difference in weight lifted. Clarify this aspect both in the text and in the table caption.

Comparison between groups. A paragraph directly comparing the two groups is missing. Furthermore, Table 7, referenced at line 177, appears to have been omitted. I invite you to include the analysis and table necessary to compare outcomes between the groups.

Discussion
The discussion would benefit from a more in-depth comparison with the existing literature. I suggest discussing:

• other studies that have evaluated the use of fitness applications;
• other studies that have analyzed physical activity protocols similar to yours;
• other studies that, like yours, have compared in-person physical activity with app-based approaches.

For each of these areas, evaluate whether your results are in line with those previously reported or whether they deviate from them.

Lines 216–220. The use of percentages is useful for communicating the magnitude of changes. However, these values are not presented in the Results section. I suggest adding a column in the relevant tables showing the pre- and post-intervention differences and the corresponding percentages of improvement.

Limitations and future perspectives. A paragraph dedicated to the limitations of the study is missing. Add it. Among the limitations, you should include convenience sampling (correctly cited earlier) and, if not controlled for, the absence of a nutritional assessment during the study period. Furthermore, the fact that the APP group was not supervised should be mentioned as a limitation. Future perspectives can be drawn from the Conclusions section, in order to make the latter more concise.

Conclusions
Following the relocation of the future perspectives, I ask you to lighten the conclusions, possibly keeping only one sentence on future perspectives, as suggested above.

Best Regards

Author Response

Dear reviewer,

We would like to begin by sincerely thanking you for your thoughtful and constructive comments on our manuscript. We greatly appreciate the time and effort you have dedicated to evaluating our work, as well as your valuable suggestions for improvement. Your critical observations have helped us identify important methodological and statistical limitations, and we believe the manuscript has been substantially strengthened as a result of your input. Below, we provide a point-by-point response to each of your comments, indicating the changes made to the manuscript.

Comment 1:
The introduction, although detailed, relies on a limited number of bibliographic references (only five). I suggest expanding the literature review to better contextualize the importance of a healthy lifestyle in counteracting overweight, obesity, and related diseases…

Response 1:
Thank you for this observation. Following the reviewer’s suggestion, we have expanded the literature review in the introduction by incorporating multiple recent references. These additions address the most current data available and further contextualize the role of a healthy lifestyle and physical exercise in counteracting overweight, obesity, and related diseases.

Comment 2:
Group nomenclature. In the text, the groups are referred to inconsistently (e.g., experimental group A/B, control group)...

Response 2:
We agree with the reviewer’s comment. To ensure consistency, we have now used two descriptive names throughout the entire manuscript when referring to the groups, thereby resolving the previous lack of uniformity in terminology.

Comment 3:
Participant allocation. You do not specify how participants were divided into the two groups. I ask you to clarify the allocation method used...

Response 3:
We thank the reviewer for raising this point. The manuscript now explicitly states that participant allocation was performed randomly. Additionally, we have included a statistical analysis demonstrating that no significant differences were observed between the S1RM and App groups at baseline for any of the outcome variables.

Comment 4:
Ethical considerations and informed consent. This section should be renumbered as subparagraph 2.2. Add the sentence that appears later in the text, indicating the institutional ethics committee with its reference number and date of approval: "The study protocol was approved by the corresponding institutional ethics committee."

Response 4:
Both requests have been addressed. The section has been renumbered and the sentence indicating the approval by the institutional ethics committee, including its reference number and date of approval, has been incorporated as suggested.

Comment 5:
From line 96 to 103 (including Tables 1 and 2). These contents should be moved to a new subsection of the Results, entitled "3.1 Population". I will discuss this later in the Results section.
Assessment of population parameters. Add a subparagraph (e.g., 2.3) to explain how all the population parameters under examination were obtained, indicating the instruments used (for example, for bioelectrical impedance analysis, specify brand and model).

Response 5:
We have restructured the document according to the reviewer’s guidance. The relevant content has been moved to a new subsection in the Results section. Furthermore, a new subparagraph has been added to describe in detail how all population parameters were obtained, including the specific instruments used (e.g., brand and model for bioelectrical impedance analysis), the measurement procedures, and the characteristics of the population.

Comment 6:

I suggest avoiding bulleted lists. Integrate this information into a single body of text or present it in a table for better readability.
Rationale for Selection. This paragraph should be moved to the beginning of the section describing the APP, before explaining the features of the application.
Indirect Strength Assessment Protocol: The Brzycki Equation Method. This subsection should be placed immediately after the description of the training protocol for the 1RM group and before starting to discuss the APP.
Statistical analysis. Add a subparagraph dedicated to describing the statistical methods used.

Response 6:
We are grateful for these detailed suggestions. All of them have been implemented. Bulleted lists have been removed, and the information has been integrated into a single body of text or presented in a table where appropriate. A dedicated subparagraph on statistical analysis has been added, which now includes normality tests, confidence intervals, and ANOVA, allowing for statistically more robust findings and more measured conclusions, thanks to the reviewers’ comments.

Comment 7:
As indicated above, I ask you to begin the Results section with a subparagraph "3.1 Population" that presents the pre- and post-intervention characteristics in close proximity, allowing the reader a direct comparison. In practice, combine Table 1 with Table 4 and Table 2 with Table 5.
Table 5. In many cases, the p-values are reported with an extra zero (e.g., 0.00002). Modify them to standardize them with the rest of the text, for example by using "<0.001" where appropriate.
Comparison between groups. A paragraph directly comparing the two groups is missing. Furthermore, Table 7, referenced at line 177, appears to have been omitted. I invite you to include the analysis and table necessary to compare outcomes between the groups.

Response 7:
We have thoroughly revised the Results section as requested. The section now begins with subparagraph where pre- and post-intervention characteristics are presented in close proximity by combining Tables. P-values have been standardized (e.g., using “<0.001” where appropriate). Additionally, we have added a paragraph directly comparing both groups, and the missing Table has been included to provide a statistically robust comparison of outcomes between groups.

Comment 8:
The discussion would benefit from a more in-depth comparison with the existing literature...

Response 8:
We agree with the reviewer. The Discussion section has been completely rewritten to include a more in-depth comparison with recent literature, allowing us to better align our findings with or contrast them against previous studies. Moreover, given the new statistical evidence obtained, the discussion is now less overstated and more balanced.

Comment 9:
A paragraph dedicated to the limitations of the study is missing…

Response 9:
We have added a dedicated limitations paragraph within the Discussion section. This paragraph now addresses the small sample size, sex bias, lack of dietary control, and other important limitations of the study.

Comment 10:
Following the relocation of the future perspectives, I ask you to lighten the conclusions, possibly keeping only one sentence on future perspectives, as suggested above.

Response 10:
As suggested, the Conclusions section has been streamlined. It is now considerably less categorical and more firmly supported by the statistical evidence obtained, thanks to the reviewers’ comments. Only one sentence on future perspectives has been retained, in accordance with the reviewer’s recommendation.

Once again, we thank you for your insightful review and for the opportunity to revise our manuscript. We are confident that the revised version now meets the methodological and statistical standards expected by the journal. We remain at your disposal for any further clarifications or additional modifications you may deem necessary. We look forward to your final decision.

Yours sincerely,

Julio Alberto Morales Viscaya

on behalf of all the authors

Reviewer 2 Report

Comments and Suggestions for Authors

Firstly, I would like to express my gratitude for the opportunity to review this article and offer my opinion on it.

Title offers a good summary of the study's key points, but could be more concise. Suggestion: “Comparison of Supervised Indirect 1RM-Based Strength Training vs Mobile App Prescription for Body Fat Loss: A Quasi-Experimental Study”

Abstract is well written and provides a lucid overview of the study's aim and proposal, however, states that two groups carried out interventions but does not specify which is the control group and which is the experimental group. Please review this.

Line 3-4 states that “fully digital, app-based training regimen...” Please specify the type of application (algorithm-based, AI-driven, etc.).

Line 9-11 states that “...significantly greater improvements...”. It would be important to include effect size or magnitude of change.

In line15, it seems that the language is too strong (“more effective”, “underscoring”). Sugestion: “suggesting greater effectiveness”.

When using keywords, try to use different words to those in the title. It is vital to ensure that the keywords do not coincide with those present in the title, as this will serve to minimise the probability of a researcher locating the paper.

The Introduction provides a good context about the theme. However, it is based on just five references, four of which date from before 2020.

Lines 23–26: Epidemiological data should be updated (preferably post-2020 references).

Lines 41–51: Redundant explanation of indirect 1RM methods. Try to reduce repetition.

Lines 52–66: The manuscript claims to “validate” the method. This is not appropriate given the study design. Sugestion: “explores the applicability”. Besides, at the end of the introduction (the same passage), it is stated that the ‘study contributes to the field by introducing...’. However, the aim of the research is not clear. Please rewrite.

Material and Methods

The method requires fundamental adjustments.

2.1 Participants: Lines 70–72: “convenience sampling” must be clearly acknowledged as a limitation.

No sample size calculation has been performed. Please include it, otherwise the results will not be reliable.

Line 96-97 presents a Group labeling inconsistency: “The experimental group A had a mean age of 45.4 ± 2.12 years and a mean BMI of 31.63 ± 0.75 kg/m2. The control group was matched for age and baseline BMI to ensure comparability. “experimental/control” vs “Group A/B”. Must be standardized throughout the manuscript, besides the sentence doesn´t apper to be in the right place of description (Ethical Considerations and Informed Consent).

Tables 1 and 2 should be combined into a single table. Furthermore, it is missing baseline statistical comparison between groups. Please, include: p-values and baseline equivalence testing

Line100: “The experimental group B...”. Shouldn't it be ‘A’? Please, standardise.

Training protocol lacks detail (Lines 108–112): Please include rest intervals and time/cadence for the exercises as well as enter the conditions of the training venue: (temperature, humidity, ventilation, lighting, etc.)

Lines 142–143 brings the Adherence based on self-report. It must be explicitly stated as a limitation.

Lines 160–161: please, add reference immediately after formula.

The method does not describe the statistical analysis. Thus, it is not possibe understand if a proper analysis was carried out using the interaction between groups and time (ANOVA). This should be included, and effect sizes should be calculated as well.

The Results must to be restructured to better be presented. F values of an analyses time x group must to be shown.

Tables 4 and 5 should be combined into a single table including pre and pos results, p values and effects size.

Lines 175–176 mentioned the adherence, however without any statistical comparison. Please insert it.

The Discussion, and consequently Conclusion, require substantial revision to align interpretation with methodological rigor. In their current form, they overstate the strength of the evidence and do not sufficiently acknowledge key limitations, which may mislead readers regarding the validity and applicability of the findings

In Lines 192–199, claims are too Strong: “the experimental group demonstrated significantly superior improvements across all measured outcomes”. This statement is too strong and potentially misleading. Besides, the study design (non-randomized, small sample, no control of confounders) does not support causal inference or definitive superiority claims.

Throughout the discussion there are insufficient consideration of confounding variables: The absence of dietary control is not adequately integrated into the interpretation and Differences in fat mass and body composition cannot be attributed solely to the intervention. It is required to explicitly acknowledge diet as a major uncontrolled confounder affecting primary outcomes.

Lines 231–237 brings na Overgeneralization: This conclusions should be more cautious!

It would be important to have a dedicated section on the study’s limitations, which, in addition to those already mentioned, should include the lack of randomization and selection bias.

The Conclusion section is overstated and not fully aligned with the methodological limitations. It presents definitive claims that are not justified by the study design and must to be rewrite after adjustments asked.

References: It would be important to include more recent literature (post-2020) and expande the numer of references and discussion.

Author Response

Dear reviewer,

We would like to begin by sincerely thanking you for your thoughtful and constructive comments on our manuscript. We greatly appreciate the time and effort you have dedicated to evaluating our work, as well as your valuable suggestions for improvement. Your critical observations have helped us identify important methodological and statistical limitations, and we believe the manuscript has been substantially strengthened as a result of your input. Below, we provide a point-by-point response to each of your comments, indicating the changes made to the manuscript.

Comment 1:
Abstract is well written and provides a lucid overview of the study's aim and proposal, however, states that two groups carried out interventions but does not specify which is the control group and which is the experimental group…

Response 1:
We thank the reviewer for this observation. The abstract has been completely rewritten to take into account all reviewer comments as well as the changes made to the manuscript. Particular attention has been paid to the statistical analysis, discussion of results, and conclusions. The language used is now more measured and better supported by an improved statistical analysis.

Comment 2:
The Introduction provides a good context about the theme. However, it is based on just five references, four of which date from before 2020...

Response 2:
We thank the reviewer for this constructive comment. Following the reviewer’s suggestion, we have expanded the literature review in the introduction by incorporating multiple recent references (post-2020). These additions address the most current data available and further contextualize the role of a healthy lifestyle and physical exercise in counteracting overweight, obesity, and related diseases. In addition, redundancy regarding the indirect 1RM has been reduced.

Comment 3:
The method requires fundamental adjustments…

Response 3:
We are grateful for the reviewer’s detailed observations. Several fundamental adjustments have been made to the Methods section as follows:

• The manuscript now explicitly states that participant allocation was performed randomly.

• A statistical analysis has been included demonstrating that no significant differences were observed between the S1RM and App groups at baseline for any of the outcome variables.

• To ensure consistency, two descriptive names have been used throughout the manuscript when referring to the groups, thereby resolving the previous lack of uniformity in terminology.

• Details regarding exercise cadence and the conditions of the training venue have been added.

• A dedicated subparagraph on statistical analysis has been included, which now covers normality tests, confidence intervals, and ANOVA, allowing for statistically more robust findings and more measured conclusions.

Comment 4:
The Results must to be restructured to better be presented. F values of an analyses time x group must to be shown…

Response 4:
We thank the reviewer for this guidance. The Results section has been completely rewritten taking into account the reviewer’s comments as well as those of the other reviewers. The section now includes F values, confidence intervals, effect sizes, and ANOVA analysis. In addition, a paragraph directly comparing both groups has been added, and the previously missing table has been included to provide a statistically robust comparison of outcomes between groups.

Comment 5:
The Discussion, and consequently Conclusion, require substantial revision to align interpretation with methodological rigor…. In their current form, they overstate the strength of the evidence and do not sufficiently acknowledge key limitations, which may mislead readers regarding the validity and applicability of the findings.

Response 5:
We fully agree with the reviewer’s assessment. As noted, the previous version overstated the strength of the evidence and did not sufficiently acknowledge key limitations. Therefore, both the Discussion and Conclusions sections have been rewritten. The statements are now less forceful, more honest, and more consistent with the statistical evidence obtained. Furthermore, a limitations subsection has been added to the Discussion, which addresses the small sample size, sex bias, lack of dietary control, and other important limitations of the study.

Comment 6:
The Conclusion section is overstated and not fully aligned with the methodological limitations. It presents definitive claims that are not justified by the study design and must to be rewrite after adjustments asked.
References: It would be important to include more recent literature (post-2020) and expand the number of references and discussion.

Response 6:
We thank the reviewer for these recommendations. Both directives have been followed. The manuscript now includes a greater number of recent references (post-2020) throughout, and the Conclusions section has been completely rewritten to align with the methodological limitations and the statistical evidence obtained, avoiding definitive claims not justified by the study design.

Once again, we thank you for your insightful review and for the opportunity to revise our manuscript. We are confident that the revised version now meets the methodological and statistical standards expected by the journal. We remain at your disposal for any further clarifications or additional modifications you may deem necessary. We look forward to your final decision.

Yours sincerely,

Julio Alberto Morales Viscaya

on behalf of all the authors

Reviewer 3 Report

Comments and Suggestions for Authors

General Comments

In my evaluation, this manuscript addresses a relevant and practically meaningful question, namely the comparison between supervised resistance training based on indirect 1RM estimation and app-based exercise prescription in individuals with obesity. I appreciate the applied nature of this work and its potential implications for real-world exercise programming. However, despite this practical relevance, I find that the study is methodologically limited, statistically underdeveloped, and conceptually overstated.

Most critically, I am not convinced that the study design supports the strength of the conclusions presented. The quasi-experimental approach, combined with a very small sample size (n = 20), convenience sampling, and the absence of randomization, introduces substantial threats to internal validity. As a result, I believe that the claims regarding the superiority of the supervised intervention are not sufficiently supported by the data.

From a statistical perspective, I find the analysis insufficient. The manuscript relies almost exclusively on p-values, without reporting effect sizes, confidence intervals, or any assessment of practical significance. In such a small sample, this approach is particularly problematic, as statistical significance may be unstable and potentially misleading.

I am also concerned that the comparison between groups is fundamentally confounded. The study does not isolate a single variable but instead compares two complex and substantially different intervention models (supervised vs unsupervised, objective vs subjective load prescription, structured vs algorithm-based programming). Therefore, I do not consider it appropriate to attribute the observed differences specifically to the indirect 1RM method.

I see potential in this work as an exploratory or pilot study, I do not believe that, in its current form, it meets the methodological and analytical standards required for a high-quality scientific publication.

Specific Comments

1. Study Design and Internal Validity (Lines 4–11, 69–73)

I am concerned that the quasi-experimental design is not adequately problematized in the manuscript. The absence of randomization and the use of convenience sampling introduce a high risk of selection bias, which is not sufficiently acknowledged.

What should be improved:

The authors should explicitly recognize the limitations in causal inference.

2. Confounding of Intervention Components (Lines 60–66, 136–143)

In my view, the comparison is conceptually flawed because multiple variables differ simultaneously between groups. This includes supervision, load prescription strategy, and progression structure.

What should be improved:

The manuscript should clearly acknowledge that the effect of the indirect 1RM method cannot be isolated.

3. Sample Size and Statistical Power (Lines 5–6, 70–72)

I find the sample size critically insufficient for reliable inference. With only 10 participants per group, the study is highly vulnerable to both Type I and Type II errors.

What should be improved:

A power analysis is missing and should be addressed.

4. Statistical Analysis – Major Limitations (Lines 10–11, Tables 4–7)

I am not satisfied with the statistical reporting. The exclusive reliance on p-values, without effect sizes or confidence intervals, limits the interpretability of the findings.

What should be improved:

Include effect sizes and confidence intervals.

5. Interpretation of Borderline Results (Lines 186–187, 204–205)

I find the interpretation of non-significant results overly simplistic. Values such as p = 0.051 or p = 0.059 are treated as definitive non-effects, without considering statistical power.

What should be improved:

Interpret these findings more cautiously.

6. Lack of Dietary Control (Lines 259–262)

In my opinion, the lack of dietary control represents a major limitation, particularly in a study focused on body composition.

What should be improved:

This issue should be emphasized earlier and more strongly.

7. Measurement Validity (Lines 79–80)

I note that bioelectrical impedance analysis was used, but measurement conditions are not described.

What should be improved:

Clarify standardization procedures.

8. Overinterpretation of Results (Lines 192–199, 245–246)

I find the conclusions overstated. The manuscript repeatedly uses strong causal language such as “more effective,” which is not justified given the design.

What should be improved:

Adopt a more cautious tone.

9. Terminology: Control Group (Lines 71–72, 116–123)

I do not agree with the use of the term “control group,” as both groups received active interventions.

What should be improved:

Use more accurate terminology.

10. Claim of Validation (Lines 52–55)

I find the claim that the study “validates” the Brzycki equation misleading, as no validation procedure was conducted.

What should be improved:

Correct this overstatement.

11. Adherence Measurement Bias (Lines 141–143)

I am concerned that adherence was measured differently across groups (supervised vs self-reported), which introduces bias.

What should be improved:

Acknowledge this limitation.

12. External Validity (Lines 69–70)

I note that the sample is highly homogeneous (middle-aged men from a single location), which limits generalizability.

What should be improved:

Explicitly state this limitation.

Author Response

Dear reviewer,

We would like to begin by sincerely thanking you for your thoughtful and constructive comments on our manuscript. We greatly appreciate the time and effort you have dedicated to evaluating our work, as well as your valuable suggestions for improvement. Your critical observations have helped us identify important methodological and statistical limitations, and we believe the manuscript has been substantially strengthened as a result of your input. Below, we provide a point-by-point response to each of your comments, indicating the changes made to the manuscript.

Comment (General assessment):
In my evaluation, this manuscript addresses a relevant and practically meaningful question, namely the comparison between supervised resistance training based on indirect 1RM estimation and app-based exercise prescription in individuals with obesity. I appreciate the applied nature of this work and its potential implications for real-world exercise programming. However, despite this practical relevance, I find that the study is methodologically limited, statistically underdeveloped, and conceptually overstated...

Response:
We sincerely thank the reviewer for acknowledging the practical relevance of our work. In accordance with the reviewer’s comments and those of the other reviewers, the manuscript has been significantly rewritten, particularly in the methodological and statistical analysis sections. Necessary information regarding the groups and their conditions has been added. The introduction has been expanded with relevant recent references. The Methods section now includes a dedicated subsection on statistical analysis, and the Results section now presents ANOVA, F values, Shapiro–Wilk tests for normality, t-tests, confidence intervals, and other statistical parameters. Consequently, both the Discussion and Conclusions sections have been rewritten. The statements are now less forceful, more honest, and more consistent with the statistical evidence obtained. Furthermore, a limitations subsection has been added to the Discussion, which addresses the small sample size, sex bias, lack of dietary control, and other important limitations of the study.

Comment:
I am concerned that the quasi-experimental design is not adequately problematized in the manuscript. The absence of randomization and the use of convenience sampling introduce a high risk of selection bias, which is not sufficiently acknowledged.

Response:
We thank the reviewer for raising this important concern. Participants were randomly allocated into two groups, and an analysis was performed demonstrating that no significant differences were observed between the S1RM and App groups at baseline for any of the outcome variables. Nevertheless, a limitations subsection has been added to the Discussion where all study limitations are addressed. However, despite these limitations, we believe that our findings have practical implications.

Comment:
The authors should explicitly recognize the limitations in causal inference.

Response:
We agree with the reviewer. The manuscript now clearly acknowledges in the limitations section that the effect of the indirect 1RM method cannot be isolated.

Comment:
I find the sample size critically insufficient for reliable inference. With only 10 participants per group, the study is highly vulnerable to both Type I and Type II errors.

Response:
We acknowledge that the group size is small and constitutes a limitation. This resulted from excluding individuals who did not meet a high adherence threshold to the program, a decision that cannot be retroactively modified or supplemented. However, the statistical analysis has been substantially improved with the inclusion of ANOVA, effect sizes, and confidence intervals. As a result, the findings, discussion, and conclusions are now much more measured, honest, and statistically supported than in the previous version, which tended to magnify findings or reach overstated conclusions.

Comment:
I am not satisfied with the statistical reporting. The exclusive reliance on p-values, without effect sizes or confidence intervals, limits the interpretability of the findings.

Response:
We fully agree with the reviewer and are grateful to all reviewers for allowing us to revise the manuscript. The statistical analysis is now considerably more comprehensive than in the previous version, as noted in our earlier responses.

Comment:
I find the interpretation of non-significant results overly simplistic. Values such as p = 0.051 or p = 0.059 are treated as definitive non-effects, without considering statistical power.

Response:
The findings are now interpreted more cautiously, and the analysis is no longer overly simplistic, having been substantially refined.

Comment:
In my opinion, the lack of dietary control represents a major limitation, particularly in a study focused on body composition.

Response:
We acknowledge that working with human participants entails inherent difficulties in fully controlling diet or daily activities. During this program, participants were not asked to modify their eating habits, so it can be assumed that no significant changes in diet occurred relative to their pre-intervention status. Nevertheless, we recognize that this is a limitation and that results may be significantly related to dietary factors. This issue is now discussed in the limitations subsection of the current version of the manuscript.

Comment:
I note that bioelectrical impedance analysis was used, but measurement conditions are not described.

Response:
Thanks to the reviewer’s comments and those of other reviewers, the measurement conditions and procedures are now described in much greater detail. This includes the exact model of the instruments used, the certification of the technician performing the measurements, as well as training conditions such as cadence, temperature, and lighting.

Comment:
I find the conclusions overstated. The manuscript repeatedly uses strong causal language such as “more effective,” which is not justified given the design.

Response:
This was one of the major issues with the previous version of the article and was directly related to an overly simplistic statistical analysis. The current version adopts a more cautious and honest tone, which is also statistically supported.

Comment:
I do not agree with the use of the term “control group,” as both groups received active interventions.

Response:
To ensure consistency and correctness, we have now used two descriptive names throughout the entire manuscript when referring to the groups, thereby resolving the previous lack of uniformity in terminology.

Comment:
I find the claim that the study “validates” the Brzycki equation misleading, as no validation procedure was conducted.

Response:
This overstatement has been corrected. Both the Discussion and Conclusions sections have been rewritten in accordance with the revisions described in our other responses.

Comment:
I note that the sample is highly homogeneous (middle-aged men from a single location), which limits generalizability.

Response:
This limitation is now explicitly mentioned in the limitations section of the manuscript.

Once again, we thank you for your insightful review and for the opportunity to revise our manuscript. We are confident that the revised version now meets the methodological and statistical standards expected by the journal. We remain at your disposal for any further clarifications or additional modifications you may deem necessary. We look forward to your final decision.

Yours sincerely,

Julio Alberto Morales Viscaya

on behalf of all the authors

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The authors' review appears to be extremely thorough and collaborative. They strictly followed every methodological, statistical, and formal recommendation, demonstrating a strong commitment to enhancing the manuscript's scientific quality.

Author Response

Thank you very much for your thoughtful and positive assessment of our revised manuscript.

We are truly grateful for your recognition that our review process was thorough and collaborative, and that we strictly followed all methodological, statistical, and formal recommendations. Your acknowledgement of our commitment to enhancing the scientific quality of the manuscript is highly appreciated.

We are pleased that the changes made have met your expectations, and we thank you for your valuable contribution to improving this work.

Sincerely,

The Authors

Reviewer 2 Report

Comments and Suggestions for Authors

I would like to express my gratitude for the opportunity to review this article again.

It is clear that the authors have answered and reformulated the article meticulously, adopting an assertive and objective approach. All sections have been comprehensively revised and rewritten, resulting in a text that is clearer and more scientifically informed. Pertinent information has also been incorporated to ensure clarity and alignment with the stipulated aims.

Following a thorough evaluation of the present version of the article, I am in favour of its publication.

Author Response

We would like to express our sincere gratitude for your continued engagement with our manuscript and for your willingness to review it once again.

We are honored by your observation that we have answered and reformulated the article meticulously, adopting an assertive and objective approach. It is very rewarding to learn that, in your view, all sections have been comprehensively revised and rewritten, resulting in a clearer and more scientifically informed text, and that pertinent information has been incorporated to ensure clarity and alignment with the stipulated aims.

Thank you as well for your thorough evaluation and for stating that you are in favor of publication.

We greatly appreciate your support.

Sincerely,

The Authors

Reviewer 3 Report

Comments and Suggestions for Authors

In my view, the revised manuscript shows clear effort on the authors’ part, and I appreciate the work they have invested in addressing the reviewers’ comments. The topic remains relevant, and the study’s applied nature is valuable, particularly from a practical perspective. I also acknowledge that several sections—especially the statistical reporting and methodological descriptions—have been expanded and clarified compared to the previous version. However, despite these improvements, the manuscript continues to suffer from several fundamental shortcomings that substantially limit its scientific credibility and interpretability.

1. The study still lacks true experimental control. Although the authors now state that participants were randomly assigned, the overall design remains constrained by convenience sampling and insufficient detail regarding the randomization procedure. In addition, key confounding variables—such as training exposure outside supervision and lifestyle factors—remain uncontrolled. Consequently, the design does not allow for confident attribution of observed effects to the intervention itself.
2. I remain concerned about the persistent causal overinterpretation throughout the manuscript. While I recognize that the authors have made an effort to moderate their language and include a limitations section, the text still contains statements suggesting superiority and effectiveness of one intervention over the other. Given the methodological constraints, such claims remain stronger than the data can support.
3. The issue of sample size has not been adequately resolved. I appreciate that the authors now explicitly acknowledge this limitation and interpret their findings more cautiously. Nonetheless, with only 10 participants per group, the study remains underpowered, and the risk of both false-positive and false-negative findings is substantial. The absence of an a priori power analysis further weakens the inferential strength of the results.
4. I would like to emphasize that I do recognize and appreciate the authors’ efforts to improve the statistical analysis. The inclusion of ANOVA models, effect sizes, and confidence intervals represents a meaningful step forward compared to the previous version. However, in my opinion, these improvements are still not sufficient. The absence of any correction for multiple comparisons remains a serious concern, particularly given the number of outcomes analyzed. Without such control, the risk of type I error inflation persists, and the robustness of the reported significant findings remains questionable.
5. I am not convinced by the continued reliance on “trends toward significance” as supportive evidence. Although the authors now present these results more cautiously, interpreting p-values above the conventional threshold (e.g., 0.057–0.096) as indicative of meaningful effects remains methodologically problematic, especially in the context of small sample sizes. This approach contributes to an overall pattern of overinterpretation.

I acknowledge that the manuscript has improved in several technical aspects, and I appreciate the authors’ responsiveness to reviewer feedback. Nevertheless, the core methodological and interpretative issues remain insufficiently addressed. For this reason, I do not consider the study, in its current form, sufficiently robust for publication.

Author Response

Dear Reviewer 3,

We thank you for your continued engagement with our manuscript and for acknowledging the effort we have invested in addressing previous reviewers' comments. We also appreciate that you recognize the relevance of the topic, the applied nature of the study, and the improvements made to the statistical reporting and methodological descriptions.

However, after careful consideration of your remaining concerns, we acknowledge that some of the points you raise cannot be further addressed within the scope of the current study, and we offer our perspective below

Point 1 – Uncontrolled confounding variables (lifestyle, training outside supervision, diet)

You note that key confounding variables—such as lifestyle factors, training exposure outside supervision, and dietary intake—remain uncontrolled, and that this limits our ability to attribute observed effects to the intervention itself.

Our response:
We fully acknowledge this limitation, and in fact, we already discuss it explicitly in the manuscript (Section 4.6, Limitations). Specifically, we state: "This study did not monitor or control participants' dietary intake throughout the intervention period. Nutritional habits are a well-established determinant of body composition changes… The absence of dietary control means that some of the observed changes may be partially attributable to variations in energy intake rather than the exercise interventions alone."

Unfortunately, these variables could not be controlled within the design of the present study and cannot be modified post hoc. Conducting a new controlled intervention to address this point would require substantial additional resources beyond the scope of the present study. Moreover, controlling participants' daily lifestyle outside the research facility—including their diet, physical activity beyond the prescribed sessions, and sleep patterns—is logistically not viable in a quasi-experimental study of this nature. We have explicitly acknowledged and discussed this limitation in the manuscript and have refrained from making causal claims that would require such controls.

Point 2 – Alleged causal overinterpretation and claims of superiority

You state that the manuscript still contains statements suggesting superiority and effectiveness of one intervention over the other, and that such claims remain stronger than the data can support.

Our response:
We respectfully offer a different interpretation of these results based on the statistical evidence presented. After a thorough re-examination of our Results, Discussion, and Conclusions sections, we maintain that every statement suggesting an advantage of one group over the other is directly supported by the statistical metrics reported.

For example, we write:

*"The S1RM protocol was superior for central adiposity: Significant group × time interactions favored the S1RM group for waist circumference (p = .001, η²p = 0.45) and hip circumference (p < .001, η²p = 0.92), with large effect sizes and non-overlapping confidence intervals. A significant between-group difference was also observed for visceral fat (p = .040, η²p = 0.21)."*

And:

*"The most striking findings of this study are the significant group × time interactions favoring the S1RM group for waist circumference (F(1,18) = 14.50, p = .001, η²p = 0.45) and hip circumference (F(1,18) = 217.90, p < .001, η²p = 0.92). These effect sizes are considered large, indicating clinically meaningful differences. The S1RM group reduced waist circumference by 6.5 cm (95% CI: -9.82 to -3.18 cm), compared to only 1.0 cm (95% CI: -1.52 to -0.48 cm) in the App group. The non-overlap of confidence intervals provides additional evidence for the superiority of the S1RM protocol."*

These statements are not speculative. They are direct interpretations of statistically significant group × time interactions, large effect sizes, and non-overlapping confidence intervals. We are not claiming causation beyond what the data allow; we are reporting that, under the conditions of this study, the S1RM protocol produced superior outcomes for these specific variables.

Conversely, where statistical evidence was lacking, we explicitly refrained from claiming superiority. For instance:

*"For muscle mass and fat mass, the group × time interactions showed clear trends (p = .057, .080, .093, and .096) with large effect sizes (η²p ranging from 0.18 to 0.19), but did not reach the conventional threshold for statistical significance (p < .05)."*

And:

*"The S1RM group gained 1.4 kg of muscle mass (95% CI: +0.52 to +2.28 kg) compared to 1.2 kg (95% CI: +0.45 to +1.95 kg) in the App group, and reduced fat mass by 3.4 kg (95% CI: -5.62 to -1.18 kg) compared to 0.6 kg (95% CI: -2.18 to +0.98 kg) in the App group. The confidence interval for fat mass reduction in the App group included zero, indicating that the change was not statistically significant within that group."*

Thus, we have been careful to match the strength of our claims to the strength of the statistical evidence. We believe the manuscript does not overinterpret the data.

Point 3 – Sample size and statistical power

You note that with only 10 participants per group, the study remains underpowered, and that the absence of an a priori power analysis weakens the inferential strength of the results.

Our response:
We fully acknowledge this limitation in the manuscript (Sections 2.1 and 4.6). We state explicitly that the sample size was determined by participant availability rather than an a priori power calculation, and that this limited our ability to detect small-to-moderate differences.

However, changing the sample size or adding more participants is not possible at this stage. This study involved 12 weeks of supervised training with real participants, rigorous assessments, and months of work. Repeating the intervention is logistically and financially unfeasible for our research team at this time.

We have therefore chosen to be transparent about this limitation and to interpret our findings with appropriate caution, which we believe we have done throughout the manuscript.

Point 4 – Multiple comparisons and Type I error inflation

You state that the absence of any correction for multiple comparisons remains a serious concern, and that without such control, the robustness of the reported significant findings remains questionable.

Our response:
We appreciate this methodological point. However, we would like to emphasize that the statistical analyses presented—including mixed repeated-measures ANOVA, effect sizes (partial eta squared), and confidence intervals—were those suggested by previous reviewers and are widely accepted in exercise science and clinical research.

Importantly, these metrics inherently account for sample size (N) in their calculations. For example, the F-statistic in ANOVA incorporates degrees of freedom, which are directly tied to N. Effect sizes such as η²p provide a measure of practical significance that is less sensitive to sample size than p-values alone. Confidence intervals also reflect the precision of estimates given the available data.

If a statistically significant group × time interaction (p = .001) with a large effect size (η²p = 0.45) and non-overlapping confidence intervals emerges from an analysis that already accounts for N, we believe it is important to clarify how the sample size is already accounted for within the statistical framework used. The statistical test has already "penalized" the study for having a small N through wider confidence intervals and reduced power. That a significant result was obtained despite these conservative conditions arguably strengthens, rather than weakens, the evidence for a true effect.

Regarding multiple comparisons: We acknowledge that we did not apply a correction such as Bonferroni. However, such corrections are often overly conservative, particularly in exploratory studies with small sample sizes, and increase the risk of Type II errors (false negatives). Given that our primary findings (waist and hip circumference) were highly significant (p = .001 and p < .001), they would likely survive even a stringent correction. We have also prioritized effect sizes and confidence intervals, which are less vulnerable to the multiple comparisons issue.

Point 5 – Reliance on "trends toward significance"

You state that interpreting p-values above the conventional threshold (e.g., 0.057) as indicative of meaningful effects remains methodologically problematic, especially in the context of small sample sizes.

Our response:
We would like to clarify two points here.

First, p-values near the threshold (e.g., 0.05 < p < 0.10) are widely regarded in the scientific literature as indicative of a statistical trend, particularly in exploratory research or studies with limited sample sizes. As stated in our manuscript: "though these did not reach statistical significance, likely due to the limited sample size." We present these findings cautiously and not as conclusive evidence. We do not claim superiority for muscle or fat mass; we simply report that trends were observed alongside large effect sizes.

Second, the interpretation of p-values as strictly binary (significant vs. non-significant) has been widely discussed in the statistical and biomedical literature, with increasing emphasis on viewing p-values along a continuum rather than relying solely on fixed thresholds (e.g., p < 0.05). In this context, referring to results as “trends” is intended to cautiously acknowledge patterns that may be of potential interest, particularly in studies with limited sample sizes, without presenting them as conclusive evidence. We have aimed to reflect this nuance carefully in the manuscript.

Dear Reviewer 3, we genuinely appreciate the time and rigor you have dedicated to evaluating our manuscript. We understand that the small sample size, the lack of an a priori power analysis, and the absence of dietary and lifestyle controls are legitimate scientific concerns. We have acknowledged all of these limitations explicitly in the manuscript.

However, these limitations are inherent to the study design and have been transparently acknowledged in the manuscript. Addressing them would require designing and conducting an entirely new 12-week training study with a larger sample, stricter controls, and more comprehensive monitoring. Such an endeavor is not within our current logistical or financial reach, and repeating the intervention is not feasible at this time.

What we have done is conduct an honest, transparent, and methodologically sound quasi-experimental study within the resources available to us. We have reported our findings with appropriate caution, supported every claim with statistical evidence, and clearly stated the limitations that readers should consider when interpreting the results.

We believe that the manuscript, in its current form, contributes valuable practical knowledge to the field of exercise prescription for obesity populations, and that its limitations do not render it unworthy of publication. Rather, they represent areas for improvement in future research, which we have explicitly noted.

We respectfully leave the final decision to your editorial judgment.

Sincerely,

The Authors