Please leave your comments for the authors below The aim of this study protocol is to investigate the comparative efficacy of different exercise interventions in patients with chronic non-specific low back pain. The authors panned to perform systematic review and network meta-analysis.

The strength of this study was to use standard methods in systematic reviews. Moreover, they adequately described the patient and public involvement section. However, there was some weakness in this study.

First, they had better to register the study on PROSPERO (https://www.crd.york.ac.uk/PROSPERO/). They also had better to describe registration number in PROSPERO in Abstract (see PRISMA-P checklist item 2).

Second, they had better to describe as follows: “This network meta-analysis will be reported in accordance with PRISMA NMA checklist” in “Abstract” and “Methods and analysis” in the main text.

Third, they had better to describe the planned completion date of the study in “Ethics and dissemination”.

Fourth, they had better to cite the Cochrane Handbook for Systematic Reviews of Interventions version 6.0 (updated July 2019), the latest version, as follows: “Higgins JPT, Thomas J, Chandler J, Cumpston M, Li T, Page MJ, Welch VA (editors). Cochrane Handbook for Systematic Reviews of Interventions version 6.0 (updated July 2019). Cochrane, 2019. Available from www.training.cochrane.org/handbook”. They can freely access the online Handbook version 6.0 (updated July 2019).

Fifth, they had better to describe using a revised Cochrane risk-of-bias tool for randomized trials (RoB 2) instead of the Cochrane Risk of Bias tool. The revised tool may be cited as: “Sterne JAC, Savović J, Page MJ, Elbers RG, Blencowe NS, Boutron I, Cates CJ, Cheng H-Y, Corbett MS, Eldridge SM, Hernán MA, Hopewell S, Hróbjartsson A, Junqueira DR, Jüni P, Kirkham JJ, Lasserson T, Li T, McAleenan A, Reeves BC, Shepperd S, Shrier I, Stewart LA, Tilling K, White IR, Whiting PF, Higgins JPT. RoB 2: a revised tool for assessing risk of bias in randomised trials. BMJ 2019; 366: l4898”. They can obtain the 22 August 2019 version of the tool (https://sites.google.com/site/riskofbiastool/welcome/rob-2-0-tool/current-version-of-rob-2).

Sixth, I suggest that they adopt and describe the framework by Salanti and colleagues in the GRADE recommendations and their extension for indirect comparisons and network meta-analyses, if possible (Salanti, G., Del Giovane, C., Chaimani, A., Caldwell, D. M., & Higgins, J. P. (2014). Evaluating the quality of evidence from a network meta-analysis. PloS one, 9(7), e99682. doi:10.1371/journal.pone.0099682). I recommend the framework by Salanti and colleagues because this method is easy to perform in an online tool – CINeMA – which assesses ‘Confidence in Network Meta-Analysis’ (http://cinema.ispm.ch/). Please see “11.5 Evaluating confidence in the results of a network meta-analysis” in the Cochrane Handbook for Systematic Reviews of Interventions version 6.0 (updated July 2019).