Short-Term Effects of Eccentric Strength Training on Hematology and Muscle Ultrasound in University Students

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Thank you for the opportunity to evaluate this scientific paper. In the spirit of brevity, my suggestions for authors are as follows:

1. Introduction
It is advisable to include a research question or operational hypothesis at the end of the introduction, to clearly define the purpose of the investigation. In its current form, the objective is expressed too generally.

2. Methodology
Explain in more detail the justification for choosing the 4-week duration of the intervention and mention how this decision influences the validity of the conclusions (possibly by referring to adjustments to the original plan).

3. Results
To increase readability and ease of interpretation, replace some of the dense tables with comparative graphs (e.g.: bars for pre/post intervention for VO₂max, HDL, muscle thickness).

4. Discussion
Reduce the number of redundant bibliographic references. I suggest focusing on 2–3 key studies for each key variable, including direct comparisons where relevant.

5. Conclusions
Rephrase to highlight not only the benefits found, but also the limitations of the study, including the lack of a control group, the short duration of the intervention, and the gender imbalance.

Author Response

Dear reviewer,

We appreciate the rigorous evaluation of our manuscript entitled “Effects of strength training on blood tests and muscle ultrasound in university students.” We have carefully considered the reviewers’ observations and have made the relevant changes to the text, which we detail below, organized by reviewer and section:

 

Reviewer 1

Introduction:

Comment: It is suggested to include an operational hypothesis at the end of the introduction.

Response: The end of the introduction has been reformulated by incorporating an explicit hypothesis to clarify the purpose of the study.

Methodology:

Comment: Clarify the 4-week duration.

Response: A more detailed explanation has been added regarding the interruption of the original plan due to a student strike, a justification that was already partially included in the original text (see section 2.3).

Results:

Comment: Replace some tables with graphs.

Response: Comparative graphical representations of the main variables (VO₂max, HDL, muscle thickness) have been added to facilitate reading.

Discussion:

Comment: Reduce the number of references.

Response: Although we consider that each reference offers a specific contribution, we have prioritized 2–3 key studies per main variable to simplify the discussion without losing depth.

Conclusions:

Comment: Include limitations.

Response: The main limitations of the study have been explicitly included, such as: absence of a control group, short duration of the intervention, and gender imbalance.

 

Sincerely

Reviewer 2 Report

Comments and Suggestions for Authors

Now that the focus of physical activity is on muscle, the subject matter

Introduction

is very appropriate. There is a lack of more specific content on the type of strength to be worked on and its methodological aspects, which should be much clearer for the reader. Parameters such as the type of strength, quantification, or frequency are highlighted in this section.

The effectiveness of ultrasound is indisputable, but given its low accessibility to the general public, alternatives that can come close to replicate the measurement (given the global nature of the title of the work) should be discussed.

Methods

The sample of women is very small and far from representative, and it is suggested that a pilot study be added to them. Relevant information is missing (e.g., initial level of physical fitness or aspects that bias the results).

Eccentric strength work with heterogeneous subjects should be further justified, as the literature always insists that concentric fitness is a prerequisite.

The protocol is not clear, and a picture is always positive and helps understand the context.

The inclusion of cyclic aerobic tests and their relationship to the study variables should be justified.

Discussion

There are important limitations that should be added at the end of the discussion, which cannot be generalized to women as the sample is very small (statements are made that five people should be expressed differently) and the type of strength work should be much more concrete and detailed in detail.

Conclusions

The tone of the conclusions was moderate.

Author Response

Dear reviewer,

We appreciate the rigorous evaluation of our manuscript entitled “Effects of strength training on blood tests and muscle ultrasound in university students.” We have carefully considered the reviewers’ observations and have made the relevant changes to the text, which we detail below, organized by reviewer and section:

Reviewer 2

Introduction:

Comment: Include methodological aspects related to the type of strength.

Response: The introduction has been expanded with references and methodological parameters on eccentric strength (see final section of the introduction).

Comment: Ultrasound has low accessibility; discuss alternatives.

Response: It is mentioned that anthropometric measurements were also taken using ISAK methodology, although without significant results.

Methodology:

Comment: Small female sample.

Response: It has been added to the limitations section that women were maintained in the analysis in order to preserve statistical power.

Comment: Justify the use of eccentric training in heterogeneous subjects.

Response: The study design and its novelty compared to traditional protocols are discussed and justified in the methods section.

Comment: Suggest including a graphic of the training protocol.

Response: An explanatory graphic of the training protocol has been included (see Figure 1).

Comment: Justify the use of aerobic tests.

Response: It has been added that these allow for a more comprehensive physiological view and are related to expected hematological adaptations.

Discussion and Conclusions:

Comment: Expand the limitations section at the end of the discussion.

Response: The limitations section has been strengthened with remarks on the low representativeness of women and possible methodological biases.

 

We remain at your disposal for any further clarification and once again thank you for the opportunity to improve our work through the reviewers’ contributions.

Reviewer 3 Report

Comments and Suggestions for Authors

This manuscript provides valuable insight into the short-term physiological effects of eccentric strength training on university students. The methodology is thorough, and the use of ultrasound and blood biomarkers strengthens the findings. However, there are areas requiring clarification, further detail, and editing for coherence.

 

 

 Line 2–3: The title is appropriate but could be more specific. Consider:

  “Short-Term Effects of Eccentric Strength Training on Hematology and Muscle Ultrasound in University Students”

 

 Line 6–21 (Abstract): The abstract is well-structured but too dense. Consider breaking sentence (3) into two parts for readability.

 

   Also clarify what “middle zone” refers to (line 12). This could confuse nonexpert readers.

 

 Lines 27–45: Strong rationale but could benefit from tighter focus.

 

Line 30–31: "Elevated cholesterol levels..." could cite more recent global data (current citation is from 2003).

 

Lines 44–45: "Break the monotony" is too colloquial. Consider rephrasing as “increase adherence among youth.”

 

Line 75–78: The objective is clear. However, it would be helpful to include a hypothesis.

 

Line 86: Clarify if participants were asked to abstain from other physical activities during the study.

 

 Line 105–125: The protocol design is well-detailed. However, due to its complexity, including a flowchart or visual timeline would enhance clarity.

 

 Line 121–122: State clearly the reason for interruption (student strike) earlier and reference it again in the limitations.

 

Line 156 (Table 1): Consider visually highlighting that Phase 4 was not implemented.

 

Line 165–169: Specify whether the lab tests were conducted in a fasting state for all analytes and if the testing time was standardized (e.g., morning).

 

Line 238 (Table 2): Include both median and mean for all anthropometrics to allow comparison.

 

Line 254–263 (Table 3):  Table is informative but very dense. Consider splitting into two tables: one for thickness/pennation and one for echointensity.

For EI changes (line 245), clarify whether increased EI indicates decreased muscle quality. This is important for interpretation.

 

Line 266–269 (Table 4): Highlight hematological changes relevant to health or performance.

 

For instance, why might MCHC reduction matter?

 

Line 289–294 (Table 5): The increase in LDL and total cholesterol in such a short time is concerning. Clarify whether dietary or alcohol intake was controlled—this is acknowledged in limitations but should be stated earlier as a limitation of these specific results.

 

Lines 314–317: Good summary but reiterate the intervention duration (4 weeks) here for emphasis.

 

Line 348–352: Excellent use of internal control for EI (Dif1–Dif6). This is a key strength and should be emphasized more.

 

Lines 363–372: Discussion on pennation angle is strong. Consider suggesting that future studies include fascicle length imaging.

 

 Lines 423–431: Important point—acknowledge the limitations of biochemical changes in such a short window. Good job raising this.

 

Lines 435–439: Consider elaborating slightly on the cardiovascular relevance of improved VO₂max and jump metrics.

 

Lines 440–445: The conclusion is appropriate but should note that the findings are preliminary due to short duration and lack of control group.

 

Lines 448–457: This section is thorough and honest. Consider adding that the sample is predominantly male and may not generalize across sex.

 

 Statistical reporting: Consistently italicize p-values and use leading zero (e.g., p = 0.045).

 Line 230: Confirm software version: “Stata 1” seems incorrect or incomplete.

 

Throughout: Use consistent units and abbreviations (e.g., “kg” vs. “kilograms,” “m” vs. “meters”).

 

 Reference list: Ensure formatting consistency and check for duplicate links or redundant DOIs.

 

 

Author Response

Please see the attachedment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The updated version meets the requirements.

Reviewer 2 Report

Comments and Suggestions for Authors

I have no further comments. The authors have made the requested changes

Reviewer 3 Report

Comments and Suggestions for Authors

Thank you for your thoughtful and thorough revisions to the manuscript. Your professional and constructive engagement with the comments and suggestions provided during the review process is sincerely appreciated. The clarity and quality of your edits have meaningfully strengthened the manuscript and reflect a high level of scholarly rigor.

Your contributions have resulted in a significantly improved submission, and I am pleased to offer a very positive recommendation moving forward.