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Dear authors,
I believe that the concerns raised by me and the reviewers were successfully addressed. Congratulations on your work.
[# PeerJ Staff Note - this decision was reviewed and approved by Mike Climstein, a PeerJ Section Editor covering this Section #]
Dear authors,
Unfortunately, some issues remain to be addressed before approval. In summary, your results section needs to be more clear and precise. For example, the p values presented in table 2 are derived from which analysis? Authors stated that a 2x3 ANOVA was performed, thus you need to describe the interaction, the between-groups and the within-groups data. Also, I failed to replicate some ANCOVA data presented in figure 3. For example, the difference marked between CT-48h and Con in the 50-m sprint. In addition, are the within-group and the between-group signals stated in figure 3 derived from the same analysis?
Please, carefully review your results section and presentation.
Dear authors,
Thank you for addressing my concerns and respond to reviewers requests. One issue remains regarding your figure. Please consider it carefully.
Regards
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Figure 3:
I’m sorry, but I still have issues with the figures. It says that the comparisons are adjusted for baseline values in the figure text, but there seem to be no adjustments in the figure data. The data presented in the figures seem to be pre and post-data, which is fine, but figure legends should be revised. The figure text also lacks explanations of what the p-value refers to. Readers are probably interested in two things: 1) did the training program have any within-group effect pre-to post-training for each group, and 2) Was there a significant difference between groups (based on group x time interaction p-value)
One way is to separate this in the figure by using different symbols and then explain it in the figure legends.
*Significant within-group changes, pre- to post-training, p < 0.001
**Significantly different between groups, p < 0.001
The figure only states that baseline data was adjusted for, but result sections 291-293 say many more adjustments were made and presented in the figure.
Authors have made exemplary changes based on prior feedback/review
Clean, well-designed
Nicely reported
Thank you for the updates and changes made to reflect previous review. Your article is a nice addition to the field
Dear authors,
There are important missed changes that you should address.
- Please, follow the reviewer suggestions about your figure. I agree that its presentation should be reviewed.
- Please consider the suggestion about skimming the adjusted analysis, otherwise reinforce your justification to maintain.
- Please, carefully review your data. The reviewer pointed out one inconsistency in VO2 sd data and I found a different F for VO2max.
- Please, improve the presentation of your results for clarity by explicating interactions and main effects of statistical data.
- Please, present the between-groups main effects.
- Please, review the inconsistency between the number of subjects enrolled in the study. The number in the text (268) is different than in the figure.
- Please review your vertical jump data/protocol. Did you calculate the difference between the starting and final height? If not consider to exclude this variable and explain why this does not (if not) affect your findings).
- Please, edit the subheading to provide a proper description (i.e. body composition).
- Please, consider reviewing the entire document, it's possible that I and reviewers may have missed some issues that can be found in the next rounds.
Regards
**PeerJ Staff Note:** Please ensure that all review, editorial, and staff comments are addressed in a response letter and that any edits or clarifications mentioned in the letter are also inserted into the revised manuscript where appropriate.
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I thank the author for the revised manuscript and figures.
I'm still a little confused about the figures. My suggestion was to adjust the figures this way. For example, estimated VO2 is to be presented with the following data;
CT-oh
1. Pre-test data (mean and SD)
2. Post-test data (mean and SD)
CT-48
1. Pre-test data (mean and SD)
2. Post-test data (mean and SD)
Con
1. Pre-test data (mean and SD)
2. Post-test data (mean and SD)
The data presented in the figure now seems to be the mean difference (pre-post), the same as in Table 2, but in this figure, the SD is way smaller compared to what is presented in Table 2. Table 2 should present raw data, e.i no adjusted data, and the figure is said to present adjusted data, but data on mean difference seem to exactly the same (see estimated VO2 as an example). If baseline data is adjusted, I would assume the mean difference to be different compared to what is stated in Table 2.
It also doesn't make sense to adjust the estimated VO2 for BMI since both equations contain body mass.
It feels like the authors try to find a difference between groups that probably don't exist. I think data is ok even if there are no differences between the groups. It is always difficult to compare training types and find significant differences. I'm not even sure if this data needs to be adjusted. A suggestion is to skip the adjusted data and only present statistics based on absolute values.
*table 2 probably contains error "CT-48h 36.7±37.3" for estimated VO2 (37.3 in SD is too high)
Maybe the editor has other suggestions.
Dear authors,
Please consider the reviewer's remaining comments. Also, I ask you to review your tables, most of your variables do not need the second place after the decimal point. Please, revise your vertical jumps values on tables and figures, ~230cm is not too high?
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Thanks for the clarification on Figure 3. So, the data presented in the figure is only post-test data if I understood it correctly, and it seems as if the data is on absolute values (e.g., no adjusted values).
I still think this is not the best way to visualize your data. For readers, I think it would be much better to present results in the figures from the tests before and after training. Even if the authors adjusted data for different covariates, this, in my opinion, should be reported in the figure.
If baseline values are adjusted, this should be visualized in the figures (the pre-values that are missing) so the reader can understand how much impact the training had. If the author presents pre- and post-data, the reader can quickly see visually how much effect the training had for each group.
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Dear authors, thank you for addressing the reviewer's suggestions. Please, consider the remaining issues raised and resubmit the manuscript.
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I thank the authors on the revised paper. I think most of my comments have been revised. I have a few suggestions on how to improve the paper further.
1. Method section: I think the method section has been improved. The description of the selected tests are, in my opinion, still very broadly described and could be improved even more with more details. How each test was standardized can be written with more clarity. For instance,” vertical jump” – how was this test standardized, and which equipment was used to assess flight height? Did the authors use a CMJ or SJ test? (with or without a countermovement jump). Sit-ups are another test that can be described in more detail; one example is where the hands were placed during the test. Did the authors standardize the velocity?
2. Table 2 lacks a description of what ”a” and ”b” refer to. I assume this table is based on absolute values (e.g no adjusted values).
3. Figure 3: I thank the authors for using figures to visualize data. Typically, a figure for a training study has pre and post-data for each group and test so the reader can quickly visualize how much ”impact” the training had for each group. This figure seems only to contain” baseline” values, which don't help the reader much. I encourage the author to change it. Also, according to the result section, this figure should be based on adjusted means (from an ANCOVA), but the figure does not mention it. Is the data adjusted mean or just raw data?
Lastly, if the authors decide to make a pre-post figure, maybe only highlight those data that are of particular interest to the reader (e.g., it is not necessary to make a figure with all outcomes).
Dear authors, the reviewers pointed out several concerns and suggestions that must be addressed before further evaluation. Please, consider their comments, especially regarding the training protocols description, statistic issues, and the results presentation. The use of specific tables and figures is encouraged, respectively.
**PeerJ Staff Note:** Please ensure that all review, editorial, and staff comments are addressed in a response letter and any edits or clarifications mentioned in the letter are also inserted into the revised manuscript where appropriate.
**Language Note:** PeerJ staff have identified that the English language needs to be improved. When you prepare your next revision, please either (i) have a colleague who is proficient in English and familiar with the subject matter review your manuscript, or (ii) contact a professional editing service to review your manuscript. PeerJ can provide language editing services - you can contact us at copyediting@peerj.com for pricing (be sure to provide your manuscript number and title). – PeerJ Staff
Basic reporteining
It is very good to highlight the importance of muscular strength in health in the introduction, and this reviewer agree that CT is an interesting training method to study. The "interference effect" is exciting and typically examined in adults, which the text also states. However, I would encourage authors to be more specific about why studying in children/adolescents is important. For instance, Gäbler et al. 2018 (Front Physiol) hypothesized that the interference effect is age dependent and that children probably have a potentiation effect of CT rather than an interference effect. Child vs. adult physiology differs in many ways e.g., children recover quicker, fatigue less, lower muscle power and strength and also is more adapted to aerobic activities etc., which may be good info to add to why studying CT in these age groups is interesting. I also think the introduction could be improved with more previous research on CT effects in children and adolescents (see Gäbler et al. 2018 for review). CT vs. single-mode training has been studied and is relevant to add what this specific paper adds are the comparisons of within vs between session CT which is a good knowledge gap and specifically since it also includes females.
– Abstract: Only use abbreviation when it is necessary. Removing abbreviations makes it easier for the reader to follow. It should also be spelled out in full the first time used. Abstract also lack subheadings
2.1 Lines 109-130: It is hard to follow the text flow in the study design. I think it can be shortened a lot and try to be more concise. It is a 12-week training study with three groups with tests before and after the training period. The word "natural classes" might not be the correct terminology.
Line 124-126: This part is difficult to understand. How is it possible to use blinding in a training study? If coaches supervise a program, they know which group does which training. Please clarify or consider remove.
Line 142-144: inclusion criteria 1 should include "male and female". Inclusion criteria 3: please clarify or give examples for disorders.
Line 152: difficult to understand. Please clarify the meaning of it.
Table 1. Please remove non-relevant decimals from all tables. One decimal is good enough. Same in Table 2
Table 2 All abbreviations should be put as footnotes with names spelled out. VO2 max and PACER should be replaced with 20-m shuttle run (estimated VO2max) and 20-m shuttle run (laps)
Experimental design
This study examines the effects of 12 weeks of within-session concurrent training versus between-session concurrent training on measures of aerobic fitness, muscle strength, power, and sprint ability in male and female adolescents. The study is well designed and executed, with a substantial sample size that encompasses both genders within the adolescent demographic. The findings distinctly reveal how concurrent training influences various aspects of athletic performance when contrasted with a control group. One of the study's notable strengths lies in its incorporation of a relatively intricate training design (concurrent training) that yields enduring fitness improvements within a pivotal age group, set within a school-based context.
Method: The description of the intervention is probably appropriate but should be rewritten with a focus on more details so researchers can interpret the program quality and replicate it. It would be beneficial with a table with the training program, including all relevant details such as exercises used, reps, set, intensity, and rest periods. It is also unclear how the loads in the resistance program were selected. Were there any 1RM tests? Similarly, the aerobic training program is not explained in enough detail. The authors used both MAS and HRmax, but it is unclear which one was used to determine exercise intensity. Also, which exercise test was used to determine MAS and HRmax? Please clarify.
Methods: Primary outcome and secondary outcome include the procedure of how the test was conducted. I suggest separating them into something similar to "procedure," which in detail explains how the test for the test was conducted. Primary and secondary outcome text can shortly explain which parameters were included. Please also add info on the validity and reliability of each test used. The procedure should also include information on how many test days were used and in which orders the tests were conducted.
Line 132-135: Suggest moving these to the "statistics" section
Line 203: In this paper, the authors estimate VO2max through a 20-m shuttle run test and don't use direct measurements of VO2 max. Please be consistent in text and use the "estimated VO2max" instead of just "VO2max," which could be misleading. Also, suggest not using the term CRF since 20-m shuttle run validity has been questioned as a marker of CRF (please see Welsman & Armstrong 2019). Lastly, be consistent in the terminology, use, and the term "20-m shuttle run" instead of PACER. I think that is the most commonly adopted terminology.
Line 221: This is probably a unilateral test, not a bilateral one. Please clarify.
Line 229: How was this test measured? Photocells or maybe just a stopwatch? Please add information.
Statistics: overall stats need to be double-checked. See other comments
A primary concern arises with the authors' conclusion, as articulated in line 40, asserting that "the program that included resistance training and aerobic training in the same physical education class was better at improving the CRF of adolescents." Upon scrutiny of Table 2, it is evident that the CT-0h group displayed an increase from 37.5 (SD 4.76) to 39.3 (SD 4.90), whereas CT-48h exhibited a rise from 36.7 (SD 3.7) to 37.3 (SD 3.6). The substantial variability raises doubts about the statistical significance of the observed difference. It is recommended that a standard bar plot be employed to visually depict this minute disparity, potentially elucidating the matter. A re-evaluation of the statistical analysis is advisable. Additionally, clarification regarding whether the values in Table 3 represent means and standard deviations is warranted.
Results: It would be useful to highlight some of the most important results in a plot instead of putting all data in tables. It is a quick way for the reader to visualize the effects of training. Possibly the main outcomes are most interesting.
Line 239-243: The authors seem to use ANCOVA in addition to ANOVA. However, no results seem to be reported. ANCOVA produces adjusted means that aren't reported anywhere in the result section.
The result section in general, is difficult to read. The most important is to clearly report if there are any statistically significant differences between the experimental groups and experimental groups vs control groups. Adding effect size is also a good idea. Reference to table 2 should be in first sentence. Authors seem to mix up between-group differences and within-group differences.
282-284: Please double-check statistics. I doubt that there is a statistically significant difference between the experimental groups in sprint ability and estimated VO2 max. If the authors plot data in a standard bar graph, it should be evident that the SD is high.
Line 366: one important aspect missing in this study design is a measure of “maturation” such as Tanner or peak-heigh velocity (PHV). This should be addressed and discussed mainly since this study includes participants that could be in different maturation stages, which might increase variability and, thereby, the results and interpretation of the study.
No comment
My only question here would be the choice to measure muscular strength with traditionally power-oriented tests such as vertical and broad jump. Hand grip dynamometry makes sense, but I would prefer to see the other muscular strength measures more closely aligned with the resistance training protocol itself, such as 1RM or 3- to 5RM tests of strength in a movement(s) performed by the participants during their training (chest press, leg press, etc.).
With this in mind, I'd like to see the authors defend their choice to use muscular power tests in more detail
No comment
This paper addresses an interesting and important topic with relevance for adolescent health, fitness, and possible planning of physical education class time. Methodology was conducted in a rigorous fashion, and results are explained clearly and with appropriate support from current research. I applaud the authors on a very well conducted study!
While I don't necessarily think it has to be included in the discussion, a question came to mind about possible within-session motivation for the participants. Given the age of the students, do the authors think the novelty of the CT-0h protocol could have played a role in the students providing more effort during those training sessions as compared to the CT-48h group? I know effort/motivation was not measured, so it would be conjecture, but perhaps something to be explored in future work.
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