Comments on abstract, title, references

1. The main article matches the abstract.
2. Introductory statement sets the reason for doing study.
3. Research question is clear: to compare objectively assessed physical activity and sedentary time in women self-reporting fibromyalgia with a control group.
4. Methodology:Is described
5. Results and conclusions align with aim, viz., participants with fibromyalgia spent less time than controls engaged in moderate and vigorous physical activity. The result of the study was also that both participants with fibromyalgia and without spent equal time in the sedentary state.
6. Title: Conveys the main idea without giving way the results. It is an accurate representation of the paper. But not very interesting as the result is intuitive.
7. References are in order and current.

Comments on introduction/background

1. The author’s review of literature, including a Cochrane study states why moderate to vigorous physical activity is important and that it is reduced in patients with fibromyalgia.
2. The authors state that only one study has addressed the issue of whether patients with fibromyalgia spent more time in a sedentary state.
3. Aim of study is to compare objectively assessed physical activity and sedentarity in a representative sample of women self reporting fibromyalgia with a control group.

Comment: The authors do not give any information to contradict the previous large well conducted trial(Reference 11 (Segura-Jiménez et al)). Hence, I am not clear why they felt the need to undertake this trail. Did they have any evidence to the contrary to their Reference 11 (Segura-Jiménez et al)? If yes, that paper needs to be included. Please provide clarification for why this trial should be conducted.

Comments on methodology

1. Selection of subject population process is unclear. How were subjects from the Canadian Health Measures Survey recruited?
2. A flow chart to demonstrated recruitment and study process would be useful.
3. Inclusion criteria of Self-reported fibromyalgia (SRF) (Page 5, Line 122) likely to introduce selection bias and random sampling errors as it included those with a Health Care Provider diagnosis as well as those with self-reported subjective health compared to previous year, mental health, diagnosis of mood disorder, quality of life, sleep duration, sleep problems and restorative sleep unlikely to be reproducible.
4. If the self -reported cohort were formally investigated there might be other explanations for symptoms leading to overlap between the two groups.
5. What the population size in each groups? This has not been defined.
6. The variables to be measured and statistical methods to analyse data was explained.

Comment: Level of statistical significance was not defined.

Comments on data and results

1. A flow chart showing selection of patients, recruitment strategy, excluded patients and reasons why, included patients and the 2 arms of study and control patients, data collected and final analysis number would have produced more clarity.
2. Difficult to understand how a figure of 4132 subjects [page 6, Line 152] was arrived at. Please clarify. An explanation regarding this in the paper would improve the paper.
3. What was the absolute number in study group and what was the number in the control group?
4. I do not know enough about statistics to compare a cohort of 3% against a control group of 97% of study population. A statistician's opinion would be useful.
5. Table 1: Please add explanation as columns within columns.
6. Table 1: Too much of data regarding demographics does not seem relevant to the actual question being asked. Only relevant data would be data pertaining to average steps per day, average, minutes per day of LPA and MVPA, and average minutes per day of sedentarity. Sleep,smoking, psychosocial outcomes,self reported symptoms etc were not being assessed as part of the protocol.
7. Table 1: Though p value for steps is 0.001, Why is it not considered significant? Please clarify as I feel this is a significant result.
8. The figure 1 represents data in a clear way.
9. Not able to access other detailed results.

Comments on discussion and conclusions

1. The authors state their findings in first paragraph. 2.The authors do not interpret what the meaning, relevance of importance of their result. 3.They compare and contrast their study with other studies. Bar one(Reference 11 (Segura-Jiménez et al) , other studies showed results that are largely similar but smaller effect size for MVPA.
2. One big study (Reference 11 (Segura-Jiménez et al)) that differed from current study in showing that there was significant difference in time spent in the sedentary state between patients with SRF and controls. The authors postulate this might be because of difference in recruitment strategy the two studies followed.
3. The authors state strengths as generalisability of their study due to recruitment from a national database and objectivity of measurement of physical activity.
4. They point out that the limitation of their study is inclusion of self-reported fibromyalgia in the patient group.
5. The authors have a take home message that researchers and clinicians should be not discouraged to develop intervention to reduce the sedentary activities among their patients.
6. No further research ideas have been postulated.

Comment: I feel compared to the Andalusian study (Reference 11 (Segura-Jiménez et al)) this study is much weaker because of its recruitment strategy, namely lack of exclusion of any medical cause of tiredness in the self-reported fibromyalgia group. There might well have been an overlap between the two groups. Lack of clarity of numbers involved also makes comparison difficult. This limitation makes drawing novel conclusions difficult. Would the authors please rectify and revise these points please?

Overall: 1. The recruitment strategy of including self reported cases of fibromyalgia before being reviewed by a Health care professional dilutes the applicability of the result. 2. A clear flow chart indicating the number of patients considered initially, number excluded with reasons, numbers in each study arm, number of patients who completed and number finally analysed would make this a more reliable paper. 3. As a result I find it difficult to postulate further on its findings.

Overall statement or summary of the article and its findings in your own words: The authors set out to compare objectively assessed physical activity and sedentarity in a representative sample of women self-reporting fibromyalgia with a control group. A flow chart detailing the plan of investigation is not included and is not available from the reading of the article. The inclusion and exclusion criteria are not tight giving rise to potential selection bias and random sampling errors. The statistical methods appear to be reasonable but values for statistical significance not defined. However the Figure 1 includes a lot of data that are not relevant to this paper. The Figure 1 is more informative. The results and its interpretation are however diluted by the potential inclusion of patients without fibromyalgia.

Overall strengths of the article and what impact it might have in your field: Recruitment from national database increasing generalisability. If after rectification of shortcomings the result holds, the message to increase moderate and light physical activity to improve well being of patients with fibromyalgia will help inform patients and their carers.

Specific comments on weaknesses of the article and what could be done to improve it Major points in the article which needs clarification, refinement, reanalysis, rewrites and/or additional information and suggestions for what could be done to improve the article.

1. Define patient groups clearly
2. Validate diagnosis on fibromyalgia; self reportage is likely to cause biases
3. Include flow chart of the study process so that all numbers become clearer

Minor points like figures/tables not being mentioned in the text, a missing reference, typos, and other inconsistencies.

1. Table 1 needs to modified to exclude data not relevant to trial.
2. Statistical significance to be defined