World Health Organization 2020 guidelines on physical activity and sedentary behaviour

The guidelines were developed in accordance with the processes set out in the WHO Handbook for Guidelines Development and commenced in 2019. A Guideline Development Group (GDG) was established comprising relevant experts from required disciplines as well as policy makers and end users of the recommendations, with regional and gender balance. Details of the members of the GDG are available.

At the first meeting in July 2019, the GDG reviewed and finalised the scope of the guidelines and agreed on the set of population, intervention or exposure, comparator and outcome (PI/ECO) questions and critical and important outcomes to be assessed (table 2). The GDG did not include sleep as a behaviour within the scope of these guidelines but did recognise sleep as an important health outcome when considering the impact of physical activity. Between August and February 2020, the WHO secretariat coordinated the commissioning of literature searches and systematic evidence reviews and the GDG subworking groups met virtually to review, summarise and draft preliminary recommendations.

Updating searches and new evidence reviews

The WHO guidelines on physical activity and sedentary behaviour were developed by using, and systematically updating, the evidence collated for the development of other recent national physical activity guidelines that met the following three criteria: (1) the evidence reviews had been conducted according to standard and rigorous systematic processes that were well documented; (2) the assessment of the certainty of the evidence used the Grading of Recommendations Assessment, Development and Evaluation (GRADE) method or an equivalent methodology that was clearly described and documented and (3) the evidence reviews addressed the populations of interest with no restrictions to country or country income level.

For these guidelines on children and adolescents, systematic reviews undertaken by Poitras et al, Carson et al and Okely et al were used and updated. For pregnant women, the systematic review conducted to inform the 2019 Canadian Guideline for Physical Activity Throughout Pregnancy was used and updated. For all other age and subpopulation groups, the scientific report of the Physical Activity Guidelines Advisory Group developed to inform the Physical Activity Guidelines for Americans, second edition was used and updated. Where gaps in existing evidence were identified, new umbrella reviews were commissioned and full details of these are available elsewhere.

To update the systematic reviews, an agreed set of search terms, databases and search methods, as well as standardised data extraction protocols, were employed to update the evidence. A search for systematic reviews and pooled analyses of cohort studies was conducted for the period from 2017 up to September 2019. The following databases were searched: PubMed, CINAHL, MEDLINE, EMBASE, PsychInfo, SportDiscus and Cochrane to identify reviews that were peer-reviewed, written in English with no restriction on country or country income group and inclusive of reviews including studies using subjective or objectively measured physical activity or sedentary behaviour. Searches were limited to the English language, due to resource constraint and previous experience in the field indicating that other language searches yielded very few, if any additional reviews. Table 3 provides a summary of the health outcomes assessed for each subpopulation.

Reviews that examined an association (based on levels above or below a threshold of physical activity or sedentary behaviour), and also reviews that explored the dose-response relationship between these behaviours and health-related outcomes were considered. In addition, six new umbrella reviews were commissioned to address health outcomes and populations not addressed by the above recent national physical activity guidelines; these umbrella reviews focused on the health impact of physical activity in people living with HIV/AIDS, osteoporosis and sarcopenia, the prevention of falls in older adults, the risk of adverse outcomes in adults and the health impacts of occupational physical activity.

The GDG reconvened in February 2020 to review the evidence and finalise a draft set of recommendations. They examined the quality of research contributing to each outcome identified in the PI/ECO questions and assessed the overall certainty of evidence (table 2) taking into consideration the risk of bias, inconsistency, imprecision, indirectness of the evidence and publication bias across each outcome, using the GRADE framework to rate the certainty of the evidence for each PE/ICO. Evidence profiles detailing this information for each PI/ECO are available.

The GDG considered the proposed wording of the recommendations and rated the strength of the recommendations as strong or conditional (table 2) based on the balance of benefits to harms, the certainty of evidence, sensitivity to values and preferences and the potential impact on gender, social and health equity, as well as acceptability, feasibility and resource implications. The assessment of the overall certainty of the evidence for each population group was based on an assessment across all evaluated outcomes (table 2). The GDG prioritised all-cause mortality and cardiovascular mortality as the most critical outcomes, followed by other clinical outcomes (eg, falls, depression, cognition, health-related quality of life, etc), then intermediate outcomes (eg, cardiometabolic markers, other metabolic markers) as well as physical activity risk and harms. Where there was a lack of subpopulation-specific evidence, the evidence for the general population was extrapolated but downgraded due to indirectness, when appropriate. The GDG came to consensus on each recommendation as well as the strength of recommendation ratings and voting was not required.

As required by the WHO process for guideline development, the draft guidelines were externally reviewed by seven independent reviewers, who provided feedback on the scientific evidence, its interpretation and the content of the guidelines. In addition, the draft guidelines and the evidence profiles were made available to the public and stakeholders, and feedback was sought through a global online consultation conducted between March and April 2020 and that received over 400 contributions. These inputs from scientists, practitioners and the general public were collated and used by the GDG to finalise the guidelines. These were approved by the WHO Guidelines Review Committee in August 2020.