The Impact of the Experimental ‘Grappler Quest’ Training on the Structural Profile of Brazilian Jiu-Jitsu Athletes—A Randomized Controlled Trial

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript deals with an interesting topic for sport sciences i.e. the training methodology to improve the physical fitness of athletes of BJJ.

Overall, the manuscript is complete and well explained. The introduction clearly represents the state of art. The methods are well presented. It is appreciable the meticulosity of the description of the experimental intervention. The results section is complete and well-presented. The discussion is well structured and clear, the limitations are recognized and the conclusions are complete.

There are just some minor issues that need to be addressed:

1. The abstract is too long. The number of words is more than double of the allowed. To improve the readability of this section the authors should make it more concise
2. Lines 58-59: while the sentence is generally about sports training, the citation is very specifically about ju-jitsu. Please, change the sentence or the citation for consistency.
3. Line 75: Karate is not an Olympic sport, it has just been once in XXXII Olympic Games in Tokyo
4. Lines 74-75: the literature cited is not completely in line with the intent of the previous sentence: “The training process within combat sports environments is constantly evolving, influenced by scientific research and innovative training methods”. The cited articles are only papers about evaluation tests and not on “innovative training methods”.
5. There is a consistent problem with the sample size power. Indeed, if one calculates the power: Test family = t test; Statistical test=Means: Difference between two independent means (two groups); Tail= One; Effect size d=0.65; alpha=0.05; sample size group 1=22; sample size group 2=22; the calculated power = 0.682. This result is different from the one reported in the manuscript and it highlights a weak power
6. Statistical analysis: this paragraph is too verbose. To improve the readability of the paragraph the authors should avoid general concepts of the statistical analysis and report only the statistical analysis used in the study.
7. Results: the reviewer suggests to remark the strong statistical differences (i.e. p<0.001) with a double ** or another sign.

Author Response

Please review the attached file.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

I first would like to congratulate the author for this interesting study, about an experimental training program for Brazilian Ju-Jitsu athletes. It’s a considerable effort from the researchers and the constructs involved.

The manuscript it’s overall well written and follow the IMRAD design and describes adequately the content of the research protocol. After reading I’d suggest some adjustments, some improvements, and corrections.

Despite the abstract offers a detailed description of study’s key points, I would suggest authors to synthetize it (about 200 words maximum, as reported in author’s guidelines).

The introduction presents clearly and in a detailed manner the BJJ discipline, as well as the gap in knowledge about the improvement of structural profile of BJJ athletes. Furthermore, I would suggest that the introduction should explicitly highlight and give greater emphasis to the positive effects of an adequate structural profile on the development of motor-sport specific skills and physical fitness components necessary to achieve better results, as well as the relationship between structural profile and the execution/learning of technical fundamentals of this sport.

On page 6, “Calculation of indicators, analysis and evaluation of”. This sentence seems to be incomplete, maybe it’s a typo.

On lines 261: Why authors reported 46 athletes instead of 44/48? Please, clarify it.

Regarding the study's limitations, I would suggest mentioning that it only evaluates the athletes' structural profile, without considering the effects on physical fitness components. Furthermore, it would be useful to assess gender differences for this protocol in future studies

Although the discussions are well structured and describe the research results accurately and in depth, with adequate reference to recent international findings on the topic, it would also be beneficial to expand the discussion about the positive effect of a adequate structural profile on physical fitness components/performance in the paper's main discussion section to increase the scientific scope and potential applications of the study.

Author Response

Please review the attached file.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

I would like to thank the authors for the effort and clarity in preparing this manuscript, which addresses an innovative and relevant topic in the field of combat sports training. The study is well structured and provides interesting findings that may have practical value for Brazilian Jiu-Jitsu athletes and coaches. Nevertheless, there are several aspects of the manuscript that require further clarification, refinement, or methodological adjustments to improve the scientific rigor and the overall quality of reporting. My specific comments are presented below.

 

• Introduction – comment: The introduction is generally clear and provides useful background regarding the role of structural characteristics and somatotype in combat sports. However, it tends to become somewhat redundant, as the importance of body composition and somatic build is reiterated several times. This section could be more concise, allowing the focus to shift toward the innovative aspect of the study.

 

• Introduction – comment: A more critical limitation is that the central independent variable—the Grappler Quest (GQ) training program—is only briefly mentioned. Given that this program constitutes the core intervention of the study, the introduction should present a more developed conceptual and theoretical framework. The reader is left without a clear understanding of what the GQ training specifically involves, how it differs from conventional BJJ training routines, and why it is expected to generate superior outcomes. Expanding on this point, supported by relevant references to circuit-based or functional training approaches in combat sports, would substantially strengthen the rationale of the study.

 

• Introduction – comment: The hypothesis is expressed in overly general terms, referring simply to improvements in muscle tissue and reductions in fat tissue. To increase the scientific rigor, the hypothesis should be formulated in a more detailed and precise way, linked explicitly to the concrete variables analyzed later in the paper (e.g., circumferences, muscularity indices, and somatotype components). Such a refinement would help align the introduction with the methodological rigor and analytical depth that the study later demonstrates.

 

• Lines 145–146 – comment: In the description of the sample size calculation, the manuscript reports that GPower v3.1.9.6 was used with an effect size of f = 0.65 and a power of 80%. However, it is not indicated where this effect size value originates from (previous studies, pilot data, or assumptions). The authors should clearly justify the source of this parameter. In addition, the results of the sample size estimation are not fully reported. It would be important to specify the ideal sample size obtained through GPower and then compare this with the actual number of participants included in the trial. This clarification would improve methodological transparency and allow readers to better assess whether the study was adequately powered.

 

• Line 169–comment: The section titled “Selection of research groups (procedure):” appears formatted as a stand-alone heading, but it does not follow the same structure used for the other subsections in Materials and Methods (e.g., Study design, Participants characteristics). It is unclear whether this should be treated as a formal subtitle or rather as a continuation of the participants’ description.

 

• Lines 173–177 – comment: The manuscript clearly indicates that random allocation was conducted using a random number generator after stratification by weight categories, which appropriately describes the process of random sequence generation. However, there is no information regarding allocation concealment. The authors should specify whether any mechanism (e.g., sealed opaque envelopes, centralized randomization, independent administrator) was applied to ensure that group assignments were not predictable or known in advance. This omission raises some concerns regarding potential bias in the randomization process, and further clarification is recommended to align with best practices for randomized controlled trials.

 

• Materials and Methods – comment: The manuscript does not provide any information regarding blinding. It remains unclear whether participants, trainers, or outcome assessors were blinded to group allocation. Given the nature of the intervention, participant blinding is likely not feasible; however, the absence of blinding of trainers and especially evaluators could introduce bias in the measurement of outcomes. The authors should clarify whether any procedures were implemented to blind assessors or, if blinding was not possible, acknowledge this as a methodological limitation of the trial.

 

• Figure 1 – comment: Figure 1 requires improvement in terms of clarity and formatting. The last box in the flowchart is not fully legible, which reduces the readability of the intervention process. In addition, the figure could be strengthened by adapting it to the CONSORT flow diagram standards for randomized controlled trials. This would ensure that the flow of participants (enrollment, allocation, follow-up, and analysis) is presented in a standardized and transparent manner, enhancing both the methodological rigor and the reporting quality of the manuscript.

 

• Statistical Analysis – comment: The description of the statistical procedures requires refinement. The manuscript currently states: “In the analysis of the research results, basic statistical methods were used, including the calculation of the arithmetic mean, median, standard deviation, minimum and maximum values, and the coefficient of variation.” However, these procedures should be referred to as descriptive statistics rather than “basic statistical methods.”

 

• Statistical Analysis – comment: The statistical approach presents an important limitation. The authors fragmented their analyses by applying paired tests for within-group changes and independent tests for between-group comparisons. While this strategy provides partial insights, it does not allow for the direct evaluation of the interaction effect between group (EXP vs. CON) and time (pre vs. post), which is central to a randomized controlled trial design. The most appropriate method would have been a two-way repeated measures ANOVA (2×2), or an equivalent mixed-effects model, as this would capture both the main effects and the critical group × time interaction. By fragmenting the analysis, several limitations arise: (i) increased risk of Type I error due to multiple testing, (ii) reduced statistical power to detect true differences, and (iii) limited interpretability, as it becomes unclear whether the observed changes are attributable to the intervention itself or simply to independent pre–post fluctuations within each group. Without a proper interaction analysis, the strength of the causal inference regarding the effectiveness of the Grappler Quest training is weakened. The authors should either reanalyze the data using an appropriate repeated measures model or explicitly acknowledge this as a methodological limitation.

 

• Discussion – comment: The discussion provides relevant context and integrates the findings with existing literature in combat sports, but there are important aspects that should be improved. First, the section tends to reiterate too many numerical results that have already been presented, which makes parts of the discussion read more like an extension of the results rather than a critical interpretation. A more concise presentation, focusing on the most relevant changes, would improve readability and emphasize interpretation over repetition.

 

• Discussion – comment: Another limitation is the limited depth in the causal analysis of the findings. While the authors point out the associations between training experience and the observed outcomes, they do not discuss in detail the potential physiological mechanisms behind the changes, nor do they address alternative explanations such as the reliance on indirect methods for body composition assessment. Additionally, although the limitations section acknowledges the specificity of the sample, the discussion itself should emphasize more clearly that the findings apply only to young male athletes and cannot be generalized to women or older populations.

 

• Discussion – comment: Finally, the discussion does not fully explore the practical implications of the Grappler Quest intervention. While it is described as effective, the section does not clearly explain how this program could be integrated into real-world BJJ training cycles, nor how coaches should adapt or periodize it alongside standard practice. Strengthening this point would increase the applied value of the study. Overall, the discussion would benefit from more synthesis, less repetition of results, and a stronger focus on physiological reasoning, limitations of generalization, and practical applications.

 

Author Response

Please review the attached file.

Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

The manuscript discusses the use of an exercise protocol for jiu-jitsu fighters, compared to a standard training protocol. It is well described and interesting. I would just like to suggest, even if this changes the results very little, that mixed ANOVA or Generalized Linear Mixed Models be used for statistical comparisons, because with the number of statistical tests used, it is possible to increase the probability of errors. Also, in the comparison, since Spearman was used, the correct presentation is rho or rs, not r (Pearson). 

The main question addressed by the research is an evaluation of an experimental training program for jiu-jitsu athletes. The topic of the article is relevant to the field as it addresses an important area of research which is new training protocols for wrestling athletes. Compared with current literature about brazillian jiu-jitsu it adds insight in influence of the experimental 'GRAPPLER QUEST' on structural profile results. The area where article can be improved is it's statistical analysis. The conclusions are consistent with the evidence and arguments presented and they address the main question posed. References present in the study are appropriate and relevant to the study.

Author Response

Please review the attached file.

Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

Comments and Suggestions for Authors

I would like to thank the authors for addressing the corrections and also congratulate them on the quality and rigor of their manuscript. The study is clearly presented, methodologically sound, and contributes valuable evidence to the field.