PONE-D-19-20213

Prevalence estimates of physical activity in adults and elderly from triaxial and uniaxial accelerometry. The Tromsø Study

PLOS ONE

Dear Mr Sagelv,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

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Fernando C. Wehrmeister

Academic Editor

PLOS ONE

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Additional Editor Comments (if provided):

The manuscript is very interesting and important for the field. Based on the reviewers' comments and by my assessment of the paper, I feel that this manuscript has a great potential to be published, since the authors can handle comments below. I would like to point out one more issue that was not raised by the reviewers: the choice of statistical tests. I strongly suggest to authors to choose between heterogeneity or trend p-values, not present both in tables. Maybe you can test the depart from linearity to make your choice. Also, more details about the methods of the Tromsø study should be provided in the methods section.

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Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Partly

Reviewer #2: Partly

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2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: No

Reviewer #2: Yes

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3. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

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4. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: Yes

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5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: Congratulations for your work. The article is very interesting, but some changes are necessary.

The main problem is the use of prevalence accordingo to WHO recommendation instead averages. This is a problem with accelerometry because recommendations were built based on questionaires and not in a mechanical measure. Therefore prevalence obtained with accelerometer are not applicable to WHO recomendations I strongly suggest rephrasing article for averaging measures.

Introdution:

Line 59-60:

Questionnaires are still very important because accelerometry does not include information such as domains of physical activity or subjective characteristics. Therefore, the term "replace" used here needs to be changed

Line 77-79:

Please confirm in the text if the limit used is validated for one or three axys

Methods:

It is unclear the year of data collect.

Line 161: Was used an algorithm to sleep detection or only visual inspection based on lower movimentation period? Please specify this topic and if necessary, include in limitations of study.

Line 181: Again, the main problem with the study is the use of prevalence rather than averages. Please use averages / medians in the analysis

Confirm that the MVPA variable is symmetrical to present the means. If not, use nonparametric tests and present medians.

Results:

Figure 1: I suggest exclude this Figure and thinking of other alternatives such as % of individuals with 0min of MVPA. This Figure may result in incorrect information about precentage of individuals meeting WHO recomendations because it is based on accelerometry and is not comparable with data from questionaries.

Discussion:

Please, discuss what is the meaning of MVPA with and without bouts and which movement patterns they can represent.

Lines 377-380: I suggest rephrasing the sentence. This frase seems blame older people for the lower levels of physical activity compared to Young people. Other mechanisms, such as, worse sleep indicators, lower muscle strengh and health problems may explain these changes across the life. Please, review the sentence.

Lines 382-388:

Again, these results may be due to differnece in physical activity contructs based on different intensities and bout criteria. The discussion needs further explanation about this.

Please, add discussion about mechanisms between physical activity and IMC. Even with reverse causality, some suggestion for the findings is necessary.

Please, add to the discussion a topic about what to do with the article results. Can the affect measurements in longitudinal studies using uni and triaxials accelerometers across the time? What are the authors recommendations based on article findings?

Line470-472: High acceptance rate does not mean lack of bias. You need to compare sample features and losses. At least, suggest in which direction high representativeness in the population and among different educational levels may affect the findings presented.

After the limitations, please report the strengths of the study.

Conclusion

The conclusion needs reformulation according to the suggestions of the article.

Reviewer #2: This is a cross-sectional study, which has investigated the prevalence of accelerometer-based physical activity in mid-age adults from the Tromso Study in Norway. Moreover, the authors compared estimates derived by triaxial and uniaxial accelerometers. Currently, there is substantial interest and need for population estimates of physical activity based on objective measures. The context of this paper concerning the existing literature is well described, the study is well designed, and the conclusions are mostly aligned with the methods and findings. I have minor comments that are offered for the authors to consider to clarity the paper.

1- Sorry, but I could not see tables 3, 4 and 5. They were not provided in the main manuscript file, and I could not find any other alternative file with the submission.

2- Would be essential to report on the abstract the place where the accelerometers were worn.

3- It is not clear in the abstract whether the prevalence of physical activity (PA) presented (22% and 70%) are from triaxial or uniaxial. Given the comparison between triaxial and uniaxial is part of the study aims, it would be important to make it clear in the abstract.

4- A significant amount of the study relied on comparing the compliance with physical activity guidelines. However, it is essential to note that the current guidelines of 150 minutes per week of MVPA are mostly based on shreds of evidence from self-report data. The manuscript would gain by discussing this issue.

5- The sampling process and the design of the study are not clear. Is the Tromso 7 a follow-up measure from Tromso 1, or is it a new cohort that started in 2015? Is this a cohort study or a series of cross-sectional studies?

6- Please consider describing the sample from the starting sample size at recruitment, and the comparison of the analytical sample with the original sample. How to the 5918 participants compare with the overall population? The strength is the population-based design, but the reader cannot ascertain how representative the sample is.

7- Page 8, line 187 – see ‘triacial’

8- Presenting standard deviations and means would be preferable instead of standard errors for the means, as it gives to the reader a clearer idea on the variability of the data.

9- Page 9, line 213-215. It is not clear. Please review.

10- Although the difference in the prevalence of PA 10-min bouts between the triaxial and uniaxial was 4 percentage points, there was a 15-percentage points difference when non-bout was considered. Could it be further discussed in the discussion section?

11- Page 14, line 353; please review ‘These’ and use ‘those’ instead.

12- Page 17, line 410. Please note that for a prevalence of 22%, ‘4% lower’ would mean 21.2%. The difference between 22% and 18% represents 4 percentage points…Alternatively, the authors could say that the prevalence of 18% is approximately 20% lower than prevalence of 22%.

13- The conclusion retells the results and does not provide directions. The ‘so what?’ is missing in conclusion.

14- English language wording needs to be checked, as there are minor errors throughout the paper.

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Reviewer #1: No

Reviewer #2: No

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PONE-D-19-20213R1

Prevalence estimates of physical activity in adults and elderly from triaxial and uniaxial accelerometry. The Tromsø Study

PLOS ONE

Dear Mr Sagelv,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

We would appreciate receiving your revised manuscript by Dec 13 2019 11:59PM. When you are ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter.

To enhance the reproducibility of your results, we recommend that if applicable you deposit your laboratory protocols in protocols.io, where a protocol can be assigned its own identifier (DOI) such that it can be cited independently in the future. For instructions see: http://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols

Please include the following items when submitting your revised manuscript:

• A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). This letter should be uploaded as separate file and labeled 'Response to Reviewers'.
• A marked-up copy of your manuscript that highlights changes made to the original version. This file should be uploaded as separate file and labeled 'Revised Manuscript with Track Changes'.
• An unmarked version of your revised paper without tracked changes. This file should be uploaded as separate file and labeled 'Manuscript'.

Please note while forming your response, if your article is accepted, you may have the opportunity to make the peer review history publicly available. The record will include editor decision letters (with reviews) and your responses to reviewer comments. If eligible, we will contact you to opt in or out.

We look forward to receiving your revised manuscript.

Kind regards,

Fernando C. Wehrmeister

Academic Editor

PLOS ONE

Additional Editor Comments (if provided):

Congratulations for the authors for this new version of the paper. Based on the assessment of the reviewers and myself, I believe that the paper deserves be published in Plos One. However, some minor points need attention. According to reviewer 2, the paper will benefit from a more detailed discussion on the impact of these kind of measure on public health. Authors should consider expand the discussion on this specific point. Other comment is regarding the title. I will suggest that the authors use terms like "levels" instead prevalence. Why? The paper has 6 tables showing details of the parameters obtained with accelerometer, and only one figure for prevalence. So the component of "levels" in the manuscript is crucial for understanding it.

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Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #1: (No Response)

Reviewer #2: All comments have been addressed

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2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Partly

Reviewer #2: Yes

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: Yes

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: Yes

**********

6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: I understand your argument when use the reference “Ekelund et al., 2019, BMJ” to justify the use of 150 minutes. In other hand, accelerometry measure includes many decisions not included in self-report. When asked about your habitual physical activity, the answer probably will not include an exact definition of bout or intensity. Thus, if an individual practice sports for 1h, then this 1h will not necessarily be classified as MVPA time in accelerometry (including bout criteria, this will be very different). Therefore, to reach recommendations with accelerometry definitions is very difficult resulting in lower percentages. In addition, prevalence information, in many cases is used to show a health scenario in the world, or in the local context. If you want to keep this kind of measure, I suggest improving the discussion on the differences between prevalence measure by method and how this is used in public health. This measure may be mistakenly used as “the true” about health/physical activity scenario of population and severity of this scenario may vary greatly according to accelerometry decisions. The message of the article is unclear about what to do with this prevalence and how it may impact or apply to public health. Often, “more physical activity” is the final message, but in your case, you show a percentage of population reaching an expected value, so what to do with this percentage so different from previous self-report studies needs further explanations.

Reviewer #2: Thank you for the opportunity to review this manuscript. I do not have further considerations.

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7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #1: No

Reviewer #2: No

[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files to be viewed.]

While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email us at figures@plos.org. Please note that Supporting Information files do not need this step.

Physical activity levels in adults and elderly from triaxial and uniaxial accelerometry. The Tromsø Study

PONE-D-19-20213R2

Dear Dr. Sagelv,

We are pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it complies with all outstanding technical requirements.

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Fernando C. Wehrmeister

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

The authors appropriate deal with the comments from the editor and the reviewer. The paper is very nice and will be important for the field of physical activity objectively measured. Congratulations!

Reviewers' comments: