Effect of School-Based Endurance and Strength Exercise Interventions in Improving Body Composition, Physical Fitness and Cognitive Functions in Adolescents
and Emilio Villa-González †
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsRecommendations for authors:
1. We know that researchers, in general, follow a theme in their work, but it is preferable not to make self-citations, even if the co-authors are different. Reference no. 55.
2. In my experience the use of the Shapiro-Wilk test is applicable on a group of up to 50 subjects (n<50). The study includes 72 subjects (n>50), this fact which recommends the use of the Kolmogorov-Smirnov test. (The data obtained may be identical but..., this is a recommendation for future studies, just a recommendation!).
3. As we know, the modification-adaptation, in the positive sense, of the motor qualities of strength and resistance requires longer periods of intervention of the provoked variables. 4. The conclusions refer to a review (https://www.researchgate.net/publication/334909605_The_Effects_of_High-Intensity_Interval_Training_on_VO2_max_in_Different_Groups_A_Review) to prove a similarity between the results. The review, in turn, refers to another article (Martins C, Kazakova I, Ludviksen M, Mehus I, Wisloff U, Kulseng B, Morgan L, King N. High-Intensity Interval Training and Isocaloric Moderate-Intensity Continuous Training Result in Similar Improvements in Body Composition and Obese Individuals. 2016 Jun;26(3):1123/ijsnem. 2015 Oct 19. PMID: 26479856. in which the provoked variable consisted of a training program with three training sessions per week for 12
weeks, thus the similarity does not exist, and the invoked variables (Physical Education class) corset the study. It is preferable to avoid these situations in the future.
I also propose some changes in the text:
Line 518. It is preferable to stay within the study and avoid ambiguous or wishful recommendations and keep the direction of the study without entering the pedagogical dimension of teaching styles...
Line 531. Reference is made to the sample - the diversity of the sample, in this case the normal question arises: what is the population - the group from which the sample was obtained? How was the sampling done?
Line 547. Future research plans are not required in this study.
Line 555. Desiderata unrelated to the present study may be omitted.
Author Response
Recommendations for authors:
- We know that researchers, in general, follow a topic in their work, but it is preferable not to make self-citations, even if the co-authors are different. Reference no. 55.
Answer 1: Thank you for your comment. We understand the concern regarding self-citation and the importance of avoiding over-reliance on one's own work. However, we believe that reference 55 is essential to provide critical context and support for the specific point being raised. The work cited in reference 55 is a fundamental study in this area and is directly aligned with the methodology and research design used in the present study. The citation is relevant due to the specific focus on the effects of the same type of intervention in a similar population, which offers an indispensable comparison to interpret our results. We have carefully reviewed the literature, and while we strive to limit self-citation, in this case it is necessary to ensure that the scientific basis and previous contributions to the field are properly recognized.
- In my experience, the use of the Shapiro-Wilk test is applicable in a group of up to 50 subjects (n<50). The study included 72 subjects (n>50), which recommended the use of the Kolmogorov-Smirnov test. (The data obtained may be identical but..., this is a recommendation for future studies, just a recommendation!)
Answer 2: Thank you for your recommendation regarding the choice of normality test. We recognize that the Kolmogorov-Smirnov test is commonly recommended for larger sample sizes (n > 50). However, we selected the Shapiro-Wilk test because of its increased sensitivity and power to detect deviations from normal, even in samples larger than 50 participants. That said, we welcome your valuable suggestion and, for future studies, will consider performing both tests where appropriate to provide a more comprehensive analysis.
- As we know, the modification-adaptation, in a positive sense, of the motor qualities of strength and endurance requires longer periods of intervention of the variables caused.
Answer 3: Thank you very much for this insightful observation. We agree that longer periods of intervention are often required to observe significant adaptations in motor qualities such as strength and endurance. The duration of the intervention in our study (8 weeks) was chosen based on the limitations of the academic calendar and the need to fit within the structure of the physical education program. While the intervention produced positive results, we recognize that long-term interventions could produce even more substantial improvements in these motor qualities. We have added a note in the Discussion section on page 12, paragraph 4 lines 587-593, acknowledging the limitations of intervention duration and suggesting that future studies could explore longer intervention periods to better capture the full range of potential adaptations in strength and endurance.
Proposal for revision in the manuscript:
"It is important to recognize that the duration of the intervention in this study (8 weeks) may not have been sufficient to elicit the full range of adaptations typically associated with improvements in motor qualities such as strength and endurance. While positive outcomes were observed within the available time frame, previous research suggests that longer intervention periods may be necessary to achieve more significant and lasting changes in these attributes [36].”
- The conclusions refer to a review (https://www.researchgate.net/publication/334909605_The_Effects_of_High-Intensity_Interval_Training_on_VO2_max_in_Different_Groups_A_Review) to demonstrate a similarity between the results. The review, in turn, refers to another article (Martins C, Kazakova I, Ludviksen M, Mehus I, Wisloff U, Kulseng B, Morgan L, King N. High-intensity interval training and continuous isocaloric moderate-intensity training result in similar improvements in body composition and obese individuals. June 2016; 26(3):1123/IJSNEM. October 19, 2015. PMID: 26479856. in which the variable provoked consisted of a training program with three training sessions per week for 12 weeks, so the similarity does not exist, and the variables invoked (Physical Education class) corseted the study. It is preferable to avoid these situations in the future.
Answer 4: Thank you for bringing this to our attention. We understand that the comparison made in the Conclusions section may have been inappropriate due to significant differences in intervention protocols and study designs. The cited review discusses the results of a training program that included three sessions per week over a 12-week period, which differs substantially from our intervention, which was limited to regular physical education classes. As you rightly pointed out, this discrepancy limits direct comparability between the two studies. We have revised the Conclusions section on page 14, paragraph 3, lines 703-704 to modified the comparison with the mentioned study and instead focus on the specific results of our study within the context of physical education. In addition, we recognize the limitations of using physical education classes as a setting for intervention and have emphasized the need to be careful when drawing parallels with other studies with different intervention intensities and durations. Once again, thank you for this important comment.
Proposal for revision in the manuscript:
"Future research should take these methodological differences into account when comparing findings between studies."
I also propose some changes to the text:
- Line 518. It is preferable to stay within the study and avoid ambiguous or illusory recommendations, and to maintain the direction of the study without entering into the pedagogical dimension of teaching styles...
Answer 5: Thank you for this valuable comment. We understand the importance of keeping the focus of the discussion strictly within the scope of the study. We have revised the text of line 518 to remove any ambiguous or speculative recommendations related to teaching styles that extend beyond the study's findings. The revised text now focuses exclusively on outcomes and their direct implications in the context of physical education. This change ensures that the discussion remains clear and aligned with the objectives of the study. The updated text can be found in the Discussion section on page 12, paragraph 3, lines 575-579.
Proposal for revision in the manuscript:
"The findings of the present study are limited to the context of physical education classes and the effects of the intervention on physical fitness and cognitive performance. As such, any conclusions must remain within the scope of these outcomes and with this type of intervention, always taking into account correct physical education planning."
- Line 531. Reference is made to the sample, the diversity of the sample, in this case the normal question arises: what is the population, the group from which the sample was obtained? How was the sampling carried out?
Answer 6: Thank you for pointing out the need for clarification on the sample population and the sampling process. We have revised the text of line 531 to provide a more detailed description of the sampled population and the sampling methodology employed. Specifically, the revised text now clarifies that the participants were secondary school students between 13 and 17 years old, selected from a single educational center in the city of Melilla. The randomization process was carried out at the class level. These details help ensure transparency and provide a clearer understanding of the study design. This change can be found in the Methods section on page 12, paragraph 5, lines 595-598.
Proposal for revision in the manuscript:
"The sample was made up of secondary school students between 13 and 17 years old, selected from a single educational center in the city of Melilla. The randomization process was conducted at the class level to ensure students were assigned into groups in a way that minimized selection bias."
- Line 547. No future research plans are required in this study.
Answer 7: Thank you for your observation. We agree that it is not necessary to mention future research directions in this section, as it is outside the immediate scope of the present study. In response, we have removed discussion of future research plans from line 547 to maintain a stricter focus on the study's findings and its implications.
Proposal for revision in the manuscript:
(The section on future research plans has been removed to maintain focus on the study's current findings and implications.)
- Line 555. Desiderata not related to the present study may be omitted.
Answer 8: Thank you for this important suggestion. We agree that any content that is not directly related to the results of the study should be omitted to ensure that the discussion remains focused and concise. As such, we have carefully reviewed line 555 and removed any "desiderata" or elements that were not directly related to the findings of the current study. The revised text now offers a more focused discussion, which is fully in line with the results of the study.
Proposal for revision in the manuscript:
(Any unrelated content has been removed from this section to ensure a clear, focused discussion of the study's findings.)
Reviewer 2 Report
Comments and Suggestions for AuthorsIntroduction:
Line 40: Be more specific in regards to what health indicators.
Line 41: To which recommendations are you referring? There are a multitude of recommendations available. So you need to be specific.
Line 42: What authors? Please directly call them out instead of using general terms like this.
Line 54: This paragraph does not appear to is basically just restating what is in the opening paragraph and as such does not add to your argument. You somewhat bring up mental health. But then spend the majority of the paragraph restating the same issues you pointed out in the opening paragraph. Either rephrase or remove.
Line 87: A citation is needed for these claims.
Line 89: remove “the” before concentration.
Line 91: explain cooperative HIIT
Line 96: The sentence that starts with however is poor grammar and needs to be revised.
Line 104: By both do you mean RT and endurance training? If so, you haven’t given any support to the claim RT benefits children cognitive health like you have with endurance training. Please do so if you wish to back up this statement.
Line 116: Please state the authors of the meta here. Not just the citation.
The overall flow of the introduction needs to be improved. It feels a bit disjointed at times. Like it jumps back and forth between general ideas about the benefits of exercise and how adolescents need to exercise more. There needs to be a clear and concise flow to the argument being made here. Additionally, due to the disjointed nature of the introduction it feels like there is a fair bit of fluff. And the intro can be stated much more succinctly.
Methods:
Line 199: This information about the population of the city is not necessary. Please remove.
Line 220: This line about the PE teacher is not necessary. Please remove.
Line 276: Were any reliability metrics for the investigator that took the waist circumference assessed? Was it the same investigator each time?
Line 328: The group conditions would be between group factors and only the pre-post intervention would be considered within participant factors.
Line 332: You mention handgrip here but not earlier in the methods. Also, was long jump not assessed with physical fitness measures?
Were any post hoc analyses done in the event of a main effect or interaction? If so, please detail them here.
The “moment” term is typically referred to as “time”. As such it is more common to refer to this as a Group x Time comparison. Please adjust the manuscript to change the moment term to time.
Results:
line 343: Same issue as my earlier comment. The group conditions are between variables. Not within. Please confirm the ANOVA was performed correctly.
Throughout the results, please detail the findings of any post hoc analysis if done. Not just refer the reader to a table.
Discussion:
Line 389: There should only be two intervention groups and one control. Additionally, the interaction tells you there's a difference. The post hoc analysis shows you where those differences are. Please discuss the post hoc results here not just leave it at the interaction.
Line 404: improvements in the stated variables in what group? Again, an interaction does not show significant improvements. It shows that changes were different between conditions. The post hoc analyses would indicate that.
This discussion has many of the same issues as the introduction. There appears to be a lot of fluff and can be stated much more succinctly. Please shorten.
Comments on the Quality of English LanguageModerate to minor grammar issues are present throughout the manuscript. Please revise accordingly.
Author Response
Comments and suggestions for authors
Introduction
Comment 1: Line 40: Be more specific about health indicators.
Answer 1: Thank you for this insightful suggestion. We agreed that being more specific about the health indicators associated with physical activity would improve the clarity of the text. We have revised line 40 to include specific health indicators such as cardiovascular health, body composition, mental well-being, and metabolic function. This change ensures that the reader understands precisely what health benefits you are referring to. This revision can be found in the Introduction section on page 2, paragraph 1, lines 40-41.
Proposal for revision in the manuscript:
"indicators, such as cardiovascular health, body composition, mental well-being, and metabolic function."
Comment 2: Line 41: What recommendations do you refer to? There are a multitude of recommendations available. Therefore, you need to be specific.
Answer 2: Thank you for pointing this out. We have revised line 41 to clearly indicate that the recommendations in question are those of the World Health Organization (WHO) regarding physical activity for adolescents. This clarification ensures that the reader knows which guidelines are being referred to. This change can be found in the Introduction section on page 2, paragraph 1, lines 42-43.
Proposal for revision in the manuscript:
"More than 80% of adolescents do not meet the recommendations of the World Health Organization (WHO), which suggest at least 60 minutes of moderate to vigorous physical activity per day."
Comment 3: Line 42: Which authors? Please call them directly instead of using general terms like this.
Answer 3: Thank you for this comment. We have revised line 42 to replace the general term "authors" with the specific citation of Guthold et al. (2020), who have conducted significant research on global levels of physical activity among adolescents. This change ensures that the reference is specific and has the appropriate attributes. This review is on page 2, paragraph 1, lines 45-46.
Proposal for revision in the manuscript:
"According to these authors (02), changing adolescents' behavior regarding PA is challenging, particularly in light of the low overall rates of activity among this population."
Comment 4: Line 54: This paragraph does not add anything to your argument. Reformulate or delete.
Response 4: We appreciate this observation and agree that the paragraph in line 54 was somewhat redundant. We've deletd this section to remove repetitive information and better align the content with the overall argument of the introduction.
Proposal for revision in the manuscript:
(The section on future research plans has been removed to maintain focus on the study's introduction)
Comment 5: Line 87: A citation is needed for these statements.
Answer 5: Thank you for pointing out the need for an appointment on line 87. We have added a relevant reference to support the claim that cognitive functions such as concentration are critical for academic success in children and adolescents. We have cited Eddolls et al. (2018) and Ludyga et al. (2019) who conducted research on cognitive functions in educational settings. This change can be found on page 2, paragraph 3, lines 96:95, and the citation has been added to the reference list.
Proposal for revision in the manuscript:
"These cognitive gains may be associated with the specific neuromuscular demands of strength training, which likely stimulate brain regions responsible for executive functions, through mechanisms involving enhanced motor coordination and muscular endurance [8; 9]".
Comment 6: Line 89: Delete "the" before the concentration.
Answer 6: We agree with this grammatical correction. In line 89, the article "the" before "concentration" has been removed to improve clarity and grammatical accuracy. This review is on page 3, paragraph 2, line 98.
Proposal for revision in the manuscript:
(The unnecessary "the" has been removed to ensure correct grammatical structure.)
Comment 7: Line 91: Explain cooperative HIIT.
Answer 7: Thank you for this important suggestion. We've expanded line 91 to include a brief explanation of what cooperative high-intensity interval training (C-HIIT) entails. The revised text clarifies that C-HIIT is a team-based approach to exercise designed to improve both fitness and cognitive outcomes by promoting teamwork and engagement. This additional detail ensures that readers who are not familiar with this concept will understand its relevance to the study. The updated explanation can be found on page 3, paragraph 2, lines 100 to 105.
Proposal for revision in the manuscript:
"specifically cooperative HIIT (C-HIIT) that involves students working together in teams to complete high-intensity exercises. This approach improves both physical fitness and cognitive outcomes by encouraging teamwork and engagement, key factors for success in adolescent physical education settings. C-HIIT improves cognitive functions (attention and concentration) are improved in adolescents aged 12-16 years, especially in inactive children [18]."
Comment 8: Line 96: The sentence that begins with "however" is poor grammar and needs to be revised.
Answer 8: Thank you for highlighting this problem. We have revised the sentence on line 96 to improve its grammatical structure and clarity. The revised sentence is now fluent in reading and accurately reflects what is being proposed. This review is on page 3, paragraph 3, lines 108-109.
Proposal for revision in the manuscript:
"Nevertheless, it is necessary to analyze the differences between age groups and types of exercise."
Comment 9: Line 104: You have not given any support to the claim that RT benefits children's cognitive health as you have with resistance training. Please do so if you wish to endorse this statement.
Answer 9: Thank you for this valuable comment. We agree that more support is needed to substantiate the claim about the benefits of resistance training (RT) for children's cognitive health. We have indicated the reference of Ludyga et al. (2019) that provides evidence of the cognitive benefits of resistance training, in this case aerobic. This review can be found on page 3, paragraph 4, lines 116-117, and the citation has been listed to the reference list.
Proposal for revision in the manuscript:
"While resistance training has been studied extensively for its cognitive health benefits, recent research also suggests that aerobic training may improve cognitive functions [9]."
Comment 10: Line 116: Please indicate the authors of the meta here. Not just the summons.
Answer 10: Thank you for this suggestion. We have revised line 116 to explicitly indicate the authors of the meta-analysis, as recommended. The new text now reads: "Costigan et al. [23] conducted a meta-analysis that demonstrated the benefits of high-intensity interval training for improving cardiovascular fitness and mental health in adolescents." This change ensures proper attribution to authors and can be found on page 3, paragraph 5, lines 1127-130.
Proposal for revision in the manuscript:
"Costigan et al. [23] conducted a meta-analysis that demonstrated the benefits of high-intensity interval training in improving cardiovascular fitness and mental health in adolescents."
Comment 11: Line 199: This information about the city's population is not necessary. Please delete.
Answer 11: We agree that information on the city's population is not essential to the methodology of the study. We have removed this sentence from line 199 to ensure that the methods section remains focused on the pertinent details of the study design.
Proposal for revision in the manuscript:
(The phrase relating to the city's population has been removed for clarity and conciseness.)
Comment 12: Line 220: This line about the physical education teacher is not necessary. Please delete.
Answer 12: Thank you for this observation. We agree that the description of the physical education teacher's qualifications is not necessary for this section of the manuscript. We have removed this phrase from line 220 to keep the focus on methodology.
Proposal for revision in the manuscript:
(The phrase describing the qualifications of the physical education teacher has been removed for clarity and conciseness.)
Comment 13: Line 276: Were any reliability metrics evaluated for the researcher who took waist circumference? Was it the same researcher every time?
Answer 13: Thank you for raising this important point. We have revised line 276 to clarify that all anthropometric measurements, including waist circumference, were taken by the same researcher to ensure consistency. Although no formal reliability metrics were evaluated, the researcher had extensive experience performing these measurements, which minimized variability. This review can be found on page 7, paragraph 1, lines 308-312, where we now explain that the same researcher performed the measurements to ensure reliability and consistency throughout the study. This change helps address concerns about measurement consistency without introducing formal reliability metrics, which were not part of the study's original design.
Proposal for revision in the manuscript:
"All anthropometric measurements, including waist circumference, were performed by the same experienced researcher to ensure consistency among participants. While no formal reliability metrics were evaluated, the researcher had extensive experience in these procedures, which minimized potential variability."
Comment 14: Line 328: The conditions of the group would be among the factors of the group and only the pre-post intervention would be considered within the participating factors.
Answer 14: Thank you for this correction. We have revised the description in line 328 to reflect that group conditions are cross-group factors, while pre- and post-intervention measurements are treated as factors within the participant. This review ensures that statistical analysis is accurately described and aligned with standard practice. The updated text is on page 8, paragraph 2, lines 369-370.
Proposal for revision in the manuscript:
"Group conditions were treated as factors between groups, while pre- and post-intervention measurements were analyzed as factors within participants."
Comment 15: Line 332: You mention the hand grip here, but not earlier in the methods. Also, was the long jump not assessed with measures of physical fitness?
Answer 15: Thank you for this observation. We've reviewed the Methods section to make sure that all physical fitness measures, including hand grip strength and standing long jump, are mentioned above to maintain consistency. This update clarifies the full suite of fitness tests used in the study. The revised text is on page 7, paragraph 2, lines 318-320.
Proposal for revision in the manuscript:
"Measures of physical fitness included hand grip strength, which assesses upper body strength, and the standing long jump, which assesses lower body strength and explosive power."
Comment 16: Have post hoc analyses been carried out? If so, please provide details.
Answer 16: Thank you for this important suggestion. We confirm that post hoc analyses were performed when a significant primary effect or interaction was detected. These analyses were used to identify specific differences between the groups. We have now added a detailed explanation of the post hoc analyses in the Results section, specifying where significant differences were found. This change can be found on page 8, paragraph 3, lines 383-386.
Proposal for revision in the manuscript:
"Post hoc analyses were performed after detection of major effects or significant interactions. These analyses identified significant differences between the intervention and control groups, particularly in the areas of aerobic capacity and muscle strength."
Comment 17: Line 343: The conditions of the group are between variables, not within. Confirm that the ANOVA was successful.
Answer 17: Thank you for your observation. We confirmed that the ANOVA was performed correctly, treating group conditions as factors between groups and pre- and post-intervention measurements as factors within participants. We have revised line 343 to clarify this distinction and ensure that the statistical analysis is accurately described. This correction is found on page 8, paragraph 4, lines 391-393.
Proposal for revision in the manuscript:
"ANOVA was conducted with group conditions as factors between groups and pre- and post-intervention measurements as factors within participants."
Comment 18: Line 389: There should only be two intervention groups and one control. Please discuss the post hoc results here, not just leave it to the interaction.
Answer 18: Thank you for this valuable suggestion. We have clarified in line 389 that there were two intervention groups (Endurance and Strength) and a control group. In addition, we have expanded the discussion of the results to include the findings of the post hoc analyses, which indicate where significant differences occurred between the groups. This review ensures that the reader has a clear understanding of group comparisons and specific outcomes of the intervention. The revised text is on page 9, paragraph 4, lines 441-447.
Proposal for revision in the manuscript:
"Post hoc analyses revealed significant differences between the resistance group and the control group in terms of improvements in aerobic capacity, while the strength group demonstrated greater gains in muscle strength compared to the control group."
Comment 19: Line 404: Improvements in the declared variables in which group? An interaction does not show significant improvements.
Answer 19: Thank you for your observation. We have revised line 460-465 to specify the groups in which improvements were observed. The text is on page 10, paragraph 3.
In the manuscript:
“In the physical fitness parameters, the group*moment interaction indicated significant improvements in grip strength, agility, and VO2 max. The SG resulted in the greatest improvements in grip strength and agility. On the other hand, the EG had a more notable effect on improving VO2 max, reflecting a significant increase in participants in the Course Navette. These differences underscore the importance of choosing the appropriate type of physical intervention based on the specific physical improvement goal.”
