Review Reports - Impact of COVID-19 Infection on Cardiorespiratory Fitness, Sleep, and Psychology of Endurance Athletes—CAESAR Study

Round 1

Reviewer 1 Report

Thank you for the opportunity to review this research. I think it is very interesting, however at this stage the document requires improvements.

The abstract should be revised, it is not fluid and easy to understand.

I suggest to the authors to consider another manuscript related to this topic as a reference to include in the document:

· Buonsenso, A., Murri, A., Centorbi, M., Di Martino, G., Calcagno, G., di Cagno, A., ... & Iuliano, E. (2022). Psychological Wellbeing and Perceived Fatigue in Competitive Athletes after SARS-CoV-2 Infection 2 Years after Pandemic Start: Practical Indications. Journal of Functional Morphology and Kinesiology, 8(1), 1.

The introduction has significant grammatical errors which makes it challenging to follow from time to time. In addition, the sentences are not well connected to each other. The introduction lacks of organizational criteria. The structure should describe the problem from the general to the aim of the study. The authors talk about endurance athletes and the benefits of physical activity, then move to the benefit of a correct diet (which is not related to the aim of the study), and finally return to the impact of COVID-19 on lifestyle.

Materials and methods section should be improved with a description of participant characteristics included in the study (e.g. age, number, type of sport). In addition, the conformity of the study according to the Helsinki statement, the approval of the ethics committee and the acceptance of informed consent by the participants are lacking.

The tables must be easy to understand, the readers should be able to understand them even without reading the text. Table 2 and 3 are very difficult to understand. What do all the values below the number and percentage indicate?

One of the objectives of the study is to evaluate how a previous mild COVID-19 infection impacts results on endurance performance scores. In the discussions the authors did not discuss the decrease in cardiorespiratory fitness but only its relationship with sleep deprivation and mental stress.

Language and grammar need the correction of a revised version by a native English speaker.

MINOR:

Line 20: “It is especially important for endurance athletes”. This sentence is not clear, please specify because Covid-19 is important for endurance athletes.

Line 21: “Sleep and psychology influence sport performance”. This sentence does not connect well with the previous sentences, please rephrase.

Lines 25-26: “completed a survey”. Which kind of survey? please specify.

Line 41: “for almost three years.[1].”. Please delete the dot after years. Revise this aspect throughout the manuscript.

Lines 51-53: “it is also well known…. affected by COVID-19”. Please support this sentence with a reference.

Lines 56-57: “EAs also adopted different coping strategies that affected men-56 tal health differently.”. Please support this sentence with a reference.

Line 98: “and a mental health”. Please remove “and”.

Line 103: “with the same type”. Please modify the sentence with “with the same exercise modality”.

Lines 103-104: “Interval between infection and both CPETs have 103 been measured to control the effect of time elapsed and adjust analysis.” What did the authors mean? “Adjust analysis” how and for what purpose?

Line 106: “[26] [27]”, please modify with “[26,27]. The same for the following sentences (e.g. line 357)

Line 116- 122: Exclusion criteria section, no numbering before (4), please modify. The same in the discussion section (lines 301-308)

Line 129-130: please enter only the reference of the article who validated the questionnaire. Three references for one questionnaire are not necessary.

Line 132: “14 questions”. Are the 14 questions only for mood state section or for all previous sections? If they are only for mood state please enter the number of questions for each item.

Lines 141-142: “EAs were asked about implemented methods”. This sentence is not clear, please modify.

Lines 148-150: “EAs could choose…. used this method regularly”. The format of this sentence is different, please modify in according to the journal’s guidelines. The same for lines 309-313.

Lines 153-154: “hour of walking sleep (participants declared precise time 153 when they walk into the bed)”. Walking sleep is not the meaning of the description in brackets. Please modify.

Line 223: Table 1. I suggest to put an asterisk “*” near the significant differences (p< 0.05) to make the results more immediate for readers. In addition, add the meaning of the asterisk in the table legend. The same for the following tables.

Line 223: Table 1. The abbreviations are not all present in the caption (e.g. P_RCP, F_Rmax), in addition P_AT is mentioned twice with a different description. Please correct and make a check for the following tables,

Line 278: Table 3. The number of participants included in the study is 49, but the total of some lines is not 49. Please revise.

Line 321: “the sleep of the correct quality and length”. Please, modify with “the correct quality and duration of sleep”. Please revise English throughout the manuscript.

Line 323: “poor sleep hygiene”. what this means? Please make this sentence clear.

Author Response

Dear Reviewer,

on behalf of co-authors of the research entitled: “Impact of COVID-19 infection on cardiorespiratory fitness, sleep, and psychology of Endurance Athletes– CAESAR study” we would like to thank you for your time and contribution during reviewing our manuscript. Moreover, we are grateful for seeing the value and importance of our work. We did our best to revise our article in accordance with your suggestions. We applied extensive English editing according to your suggestion to improve the text's structure and readability. In this file, you can find our responses. We uploaded a revised manuscript in a “tracking changes form” in MDPI Submission System.

We hope that all points were properly addressed and that our article in its present form will fulfill the requirements for publication in the Journal of Clinical Medicine.

Commentary: The abstract should be revised, it is not fluid and easy to understand.

Response: We applied grammatical revisions and improved our abstract. Currently, the text is more concise and more plausible for the reader.

Commentary: I suggest to the authors to consider another manuscript related to this topic as a reference to include in the document: Buonsenso, A., Murri, A., Centorbi, M., Di Martino, G., Calcagno, G., di Cagno, A., ... & Iuliano, E. (2022). Psychological Wellbeing and Perceived Fatigue in Competitive Athletes after SARS-CoV-2 Infection 2 Years after Pandemic Start: Practical Indications. Journal of Functional Morphology and Kinesiology, 8(1), 1.

Response: Thank you for this comment. We reviewed the literature and included this article in the introduction. This allowed us to broaden our knowledge of the impact of the disease on the course in athletes.

Commentary: The introduction has significant grammatical errors which makes it challenging to follow from time to time. In addition, the sentences are not well connected to each other. The introduction lacks of organizational criteria. The structure should describe the problem from the general to the aim of the study. The authors talk about endurance athletes and the benefits of physical activity, then move to the benefit of a correct diet (which is not related to the aim of the study), and finally return to the impact of COVID-19 on lifestyle.

Response: The introduction has been changed to maintain logical continuity. As suggested, we omitted the section on the influence of diet on the course of the disease.

Commentary: Materials and methods section should be improved with a description of participant characteristics included in the study (e.g. age, number, type of sport). In addition, the conformity of the study according to the Helsinki statement, the approval of the ethics committee, and the acceptance of informed consent by the participants are lacking.

Response: Thank you for your comment. We revised the “Materials and methods” section and added the study sample description (please see the 2.2 paragraph). Conformity of the study according to the Helsinki statement, the approval of the ethics committee, and the acceptance of informed consent by the participants were presented in the footnote at the end of the manuscript according to the journal guidelines.

Commentary: The tables must be easy to understand, the readers should be able to understand them even without reading the text. Table 2 and 3 are very difficult to understand. What do all the values below the number and percentage indicate?

Response: Thank you for pointing out this issue. We clarified our tables and added an explanation of all necessary values in the table’s footnotes.

Commentary: One of the objectives of the study is to evaluate how a previous mild COVID-19 infection impacts results on endurance performance scores. In the discussions the authors did not discuss the decrease in cardiorespiratory fitness but only its relationship with sleep deprivation and mental stress.

Response: CAESAR is a series of works, we discussed this issue in more detail in another part of the work, in the discussion we wrote "This article focuses on the outcomes of mild COVID-19 infection on sleep and mental health. Other possibly affecting covariables (including participants' sex, age, CPET modality, nutrition, training regiment, and previous sports experience) were analyzed in the remaining CAESAR manuscripts [32,33]”.

Commentary: Language and grammar need the correction of a revised version by a native English speaker.

Response: We used the help of a native speaker to make grammatical corrections in the text. Hopefully it's better quality now.

Commentary: Line 20: “It is especially important for endurance athletes”. This sentence is not clear, please specify because Covid-19 is important for endurance athletes.

Response: We rephrased this sentence.

Commentary: Line 21: “Sleep and psychology influence sport performance”. This sentence does not connect well with the previous sentences, please rephrase.

Response: We rephrased this sentence.

Commentary: Lines 25-26: “completed a survey”. Which kind of survey? please specify.

Response: We rephrased this sentence.

Commentary: Line 41: “for almost three years.[1].”. Please delete the dot after years. Revise this aspect throughout the manuscript.

Response: We took that into account.

Commentary: Lines 51-53: “it is also well known…. affected by COVID-19”. Please support this sentence with a reference.

Response: We have added the appropriate reference.

Commentary: Lines 56-57: “EAs also adopted different coping strategies that affected men-56 tal health differently.”. Please support this sentence with a reference.

Response: We have added the appropriate reference.

Commentary: Line 98: “and a mental health”. Please remove “and”.

Response: We rephrased this sentence.

Commentary: Line 103: “with the same type”. Please modify the sentence with “with the same exercise modality”.

Response: We rephrased this sentence.

Commentary: Lines 103-104: “Interval between infection and both CPETs have 103 been measured to control the effect of time elapsed and adjust analysis.” What did the authors mean? “Adjust analysis” how and for what purpose?

Response: The phrase „Adjust analysis” was redundant. We deleted it.

Commentary: Line 106: “[26] [27]”, please modify with “[26,27]. The same for the following sentences (e.g. line 357)

Response: We modified the reference order.

Commentary: Line 116- 122: Exclusion criteria section, no numbering before (4), please modify. The same in the discussion section (lines 301-308)

Response: We corrected the numbering according to your comment.

Commentary: Line 129-130: please enter only the reference of the article who validated the questionnaire. Three references for one questionnaire are not necessary.

Response: We entered only one validating study according to your comment.

Commentary: Line 132: “14 questions”. Are the 14 questions only for mood state section or for all previous sections? If they are only for mood state please enter the number of questions for each item.

Response: We have divided the description of the questionnaire into 3 sections. After each of them, we provided the number of questions it consisted of. Please see the current form of the 2.3 paragraph.

Commentary: Lines 141-142: “EAs were asked about implemented methods”. This sentence is not clear, please modify.

Response: We modified this sentence and currently it is clearer for the reader.

Commentary: Lines 148-150: “EAs could choose…. used this method regularly”. The format of this sentence is different, please modify in according to the journal’s guidelines. The same for lines 309-313.

Response: We modified both sentences according to your comment.

Commentary: Lines 153-154: “hour of walking sleep (participants declared precise time 153 when they walk into the bed)”. Walking sleep is not the meaning of the description in brackets. Please modify.

Response: We unified the statement's description in the bracket and text.

Commentary: Line 223: Table 1. I suggest to put an asterisk “*” near the significant differences (p< 0.05) to make the results more immediate for readers. In addition, add the meaning of the asterisk in the table legend. The same for the following tables.

Response: We marked significant p-values with an asterisk according to your comment. The explanation has been added in the footnote. The same procedure was applied to the following tables.

Commentary: Line 223: Table 1. The abbreviations are not all present in the caption (e.g. P_RCP, F_Rmax), in addition P_AT is mentioned twice with a different description. Please correct and make a check for the following tables

Response: We check carefully all the abbreviations and provided the lacking ones. Moreover, we deleted those presented twice and made all other necessary technical corrections in Table 1.

Commentary: Line 278: Table 3. The number of participants included in the study is 49, but the total of some lines is not 49. Please revise.

Response: We revised line no. 3, where it was a technical error. Currently, all lines include 49 participants.

Commentary: Line 321: “the sleep of the correct quality and length”. Please, modify with “the correct quality and duration of sleep”. Please revise English throughout the manuscript.

Response: We rephrased this sentence.

Commentary: Line 323: “poor sleep hygiene”. what this means? Please make this sentence clear.

Response: We rephrased this sentence.

To sum up all the above answers, we again thank you for your precise review. If you have more comments, do not hesitate to contact us.

Reviewer 2 Report

After a detailed review of the work, I can say that I was glad to have participated in this process. The work was done at the highest level from start to finish. Although the choice of the topic (Covid) may at first seem like a topic that has flooded all national journals, the authors tried to process the impact of this pandemic disease on parameters that are very important to humans, namely cardiorespiratory abilities, sleep, and mental health.

In general, the work is methodologically correctly set up. The summary is clear and concise with well-placed keywords. The introduction deals with the research problem and everything is supported with relevant references, almost all of which are extremely new, which is to be commended. In the introductory part, the authors should, for the sake of a wider readership, explain the abbreviation EAs, which will appear throughout the paper. The paper has a sufficient number of respondents for the necessary conclusion, as well as adequate instruments that have already been validated through other research, which only confirms that the paper is very well done. Also, statistical methods of analysis were correctly used and the results of the work were correctly interpreted. No matter how hard I tried to find some illogicalities and malfunctions, I did not succeed. In the discussion, the authors compared their results with earlier research and made concrete and correct conclusions based on the results and the discussion they processed. In any case, especially since it dealt with a topic that, unfortunately, is still relevant. It is also important to emphasize that the authors dealt with the impact of a mild Covid infection, which as such can be taken lightly by people, especially recreational athletes, and yet can significantly affect cardiorespiratory-mental indicators. Apart from the scientific community, the work is useful for all experts. who deal with people's health in general and in that sense had great reader potential.

Author Response

Dear Reviewer,

on behalf of co-authors of the research entitled: “Impact of COVID-19 infection on cardiorespiratory fitness, sleep, and psychology of Endurance Athletes– CAESAR study” we would like to thank you for your time and contribution during reviewing our manuscript. We did our best to prepare our article. We are grateful that you saw the value and importance of our work. We hope that our article in its present form will fulfill the requirements for publication in the Journal of Clinical Medicine.

To sum up, we again thank you for your precise review. If you have more comments, do not hesitate to contact us.

Reviewer 3 Report

I congratulate the authors for the development of the present study.

I have a few questions to ask the authors:

1- Were the training sessions controlled from December to July?

2- If the sessions were not controlled, wouldn't it be an observational study? If so, the study must follow the STROBE guidelines

3- What periodization phase were the athletes in before and after the evaluation period?

4- What are the strengths of the study?

5- What are the practical applications of the study?

6- Was the sample size performed?

7- What are the impacts of the present study for professional practice and for athletes?

8- I suggest the authors to read: https://doi.org/10.3390/ijerph20054132 and https://doi.org/10.3389/fphys.2022.949351

Author Response

Dear Reviewer,

on behalf of co-authors of the research entitled: “Impact of COVID-19 infection on cardiorespiratory fitness, sleep, and psychology of Endurance Athletes– CAESAR study” we would like to thank you for your time and contribution during reviewing our manuscript. Moreover, we are grateful for seeing the value and importance of our work. We did our best to revise our article in accordance with your suggestions. In this file, you can find our responses. We uploaded a revised manuscript in a “tracking changes form” in MDPI Submission System.

We hope that all points were properly addressed and that our article in its present form will fulfill the requirements for publication in the Journal of Clinical Medicine.

Commentary: 1- Were the training sessions controlled from December to July? 2- If the sessions were not controlled, wouldn't it be an observational study? If so, the study must follow the STROBE guidelines

Response: The aim of the period from July to December was not to control the training of athletes. In the period from July to December, participants were only recruited and invited to undergo a single post-infection CPET. We have clarified this issue in the text. Noteworthy, the CPET protocol was controlled as described in the 2.4 paragraph.

Commentary: 3- What periodization phase were the athletes in before and after the evaluation period?

Response: We did not collect data regarding our athletes' periodization phase. Thank you for paying attention to this detail. We described it in the limitations.

Commentary: 4- What are the strengths of the study?

Response: The strong point of the study is tackling an issue that is not widely known. It is unique to compare CPET results with lifestyle parameters and show which changes in the course of COVID-19 disease.

Commentary: 5- What are the practical applications of the study?

Response: Our goal is to make all people who participate in the preparation of EAs aware of the impact of COVID-19 on physical and mental health. Please note that EAs to have access to professional medical and psychological support. In a disease situation, adopting effective coping strategies can aid in the treatment and prevention of mental health issues. The influence of the lifestyle before the disease affects the course of the disease, therefore it is recommended to take care of its improvement as soon as possible - e.g. adequate length and quality of sleep, regular bedtimes.

Commentary: 6- Was the sample size performed?

Response: Yes. The sample size was calculated with the usage of G*Power software. We described this issue more precisely in the 2.5 paragraph.

Commentary: 7- What are the impacts of the present study for professional practice and for athletes?

Response: This study shows which lifestyle aspects affect CPET scores and thus motivate people to change their lifestyle to a healthy one.

Commentary: 8- I suggest the authors to read: https://doi.org/10.3390/ijerph20054132 and https://doi.org/10.3389/fphys.2022.949351

Response: Thank you for presenting these interesting texts to us. We got acquainted with them and decided to include them in the text to enrich its content.

To sum up all the above answers, we again thank you for your precise review. If you have more comments, do not hesitate to contact us.