Finally, the authors would like to extend their thanks and appreciation to members of QbTech: Tony Doyle, Charlotte Keizer, Hans Bostrom and Fredrik Ulberstad for their advice and ongoing

support. Footnotes Contributors: CH is the chief investigator and conceived and designed the study with the BET bromodomain inhibitor assistance of KS (co-investigator), DD (co-investigator), BG (medical statistician) and members of Qbtech (Hans Bostrom, Fredrik Ulberstad and Tony Doyle; co-investigators). CLH (lead research fellow) and CH wrote the protocol with approval from all authors. BG designed and wrote the statistical analysis plan. CLH, CH, AZV (researcher), GMW (research assistant), CK-H (clinical trials manager), KS and MJ (co-investigator) contributed to the drafting of the manuscript. All authors critically revised the manuscript for its important intellectual content. All authors read and approved the final manuscript. Funding: The study is funded as part of the NIHR Collaborations in Leadership in Applied Health Research and Care (CLAHRC) East Midlands, funded by a central grant from the National Institute for Health Research (NIHR), with funding from QbTech in the form of QbTest systems and returning raw data back to the study sites (QbTest reports) (Ref.PO511172). Competing

interests: None. Ethics approval: The study received ethical approval (protocol V.1.2; 05.06.2014) from NRES Committee West Midlands—Coventry and Warwick (14/WM/0166) on 11 July 2014 and has currently received local R&D approval from Alder Hey Children’s NHS Foundation Trust, Medway NHS Foundation Trust, Central Manchester University Hospitals NHS Foundation Trust, Sussex Partnership NHS Trust and Lincolnshire

Partnership NHS Foundation Trust. Provenance and peer review: Not commissioned; externally peer reviewed.
The importance of physical activity (PA) for promoting health and preventing disease is well established.1–3 However, for effective health promotion and PA surveillance and monitoring, it is important to have standardised, reliable and valid instruments that can be used to accurately describe population levels Drug_discovery and patterns of PA within and across countries.4 5 In this context, the international physical activity questionnaire (IPAQ) was developed to obtain internationally comparable data on health-related PA of adults (18–65 years).5 6 Two versions of the IPAQ that could be administered by interview or self-completed were developed. The short form (SF) was designed for population surveillance of PA; while the long form (LF) was designed to be appropriate for use in research that requires detailed information on different PA domains, including PA at work, household, during leisure and transportation and time spent in sedentary activities.