Michael Pratt

Herbert Wertheim School of Public Health&Human Longevity Science,University of California San Diego,La Jolla,CA 92093-0628,USA

Toward the end of 2020,the World Health Organization(WHO)released a new set of guidelines for physical activity and sedentary behavior.1For any aspect of health,recognition by the WHO seems a good thing,and for the oft underappreciated field of physical activity,especially so.What can we make of these guidelines?How much is really new?How strong is the science behind the guidelines?And will these guidelines really make a difference in population health around the world?In the following paragraphs,we will briefly address each of these questions.

The WHO initially developed guidelines for physical activity in 2010,2and the 1st public health-oriented guidelines for physical activity are generally considered to be those published by the Centers for Disease Control and Prevention and the American College of Sports Medicine in 1995.3The core recommendation of the“new”guidelines for adults and older adults of at least 150 min per week of moderate intensity aerobic physical activity or 75 min per week of vigorous intensity aerobic physical activity(or an equivalent combination)is very comparable to that of these previous guidelines.However,there are small but important refinements to the guidelines that represent both advancing science and an attempt to cover additional sub-populations.It has become increasingly clear that the health benefits of physical activity are associated with the total volume of physical activity,no matter the combination of intensity,duration,or type.4The new guidelines acknowledge this by removing any requirements for the length of time of periods of activity and by incorporating all intensities of physical activity.Specifically,the WHO guidelines now recommend limiting time spent being sedentary and increasing time in light intensity physical activity.As there were in the 2010 WHO guidelines,2there are also recommendations for children and adolescents,strength training(adults and older adults),and functional balance and strength training(older adults).With a growing evidence base,the guidelines have been extended to additional populations:children,adolescents,and adults living with disability,pregnant and postpartum women,and adults and older adults with chronic conditions.1So,while the basic recommendation for physical activity has changed little over the past 25 years,the guidelines have been thoughtfully revised and extended to additional populations to better reflect an expanding evidence base.

And just how strong is the evidence that regular physical activity as recommended will improve health?Remarkably strong and consistent!It is hard to overstate how important physical activity is to good health.The most comprehensive recent review was completed to provide the basis for the 2018 United States Physical Activity Guidelines.4The WHO built upon the United States’guidelines process,as well as similar national guidelines development processes in Australia,the United Kingdom,and Canada,and conducted additional systematic reviews to update the literature and support tailored recommendations for specific populations.5The quality of science supporting these guidelines is excellent,and the guidelines have been carefully calibrated to not go beyond current evidence.One obvious gap in the evidence-based reviews was the failure to address the potential roles physical activity could play in preventing and treating infectious diseases such as coronavirus disease 2019(COVID-19)—an understandable,if unfortunate,oversight given the limited but encouraging data in this area.6However,the WHO should be commended for a well-designed process that drew upon an expert committee of 40 diverse researchers and a consultation process that gathered input from around the globe.These guidelines will serve the world well for some time.As with all public health guidelines,they will require updating in a decade or so given advancing science and the need to ward off disinformation that might otherwise fill that space.

Will these guidelines go beyond good science,thoughtfully interpreted and carefully communicated,to make a real difference in the world?From a public health perspective this is a question that can be asked of most recommendations.Will evidence-based recommendations be turned into public health policy,programs,and actions that will actually improve the health of people around the world?Sadly,the answer to this question too often is no.We are all aware of recommendations that“sit on the shelf”while the world goes on as before.Only time will tell in the case of the 2020 WHO Guidelines on Physical Activity and Sedentary Behavior,1but we can hazard a guess based on factors both encouraging and sobering.The quality,inclusivity,and degree of institutional support from both the WHO and several member states throughout the process of developing these guidelines suggests that further support for dissemination and implementation may be forthcoming.The WHO has created a unit for physical activity in Geneva,small and underfunded,but an institutional home nonetheless for physical activity.The guidelines themselves have been formulated into user-friendly“good practice statements”and accessible infographics that should facilitate communication with the public and synergize well with the WHO global action plan on physical activity 2018-2030.7However,there is little evidence that any of the 6 WHO Regional Offices(aside from that for Europe)have the staff,budget,or inclination to do much around dissemination,implementation,and support for countries within their regions.Physical inactivity is a critical unresolved global health problem accounting for 5 million deaths each year.8While new guidelines and a relatively new global plan are commendable,the previous guidelines and plan were also noteworthy.2,9Getting more people to move more often will take multi-sectoral partnerships and concerted collaboration,a sustained commitment of resources,better translation of the solid intervention evidence into practice,and aggressive advocacy from those who believe that physical activity is important to good health and quality of life for everyone.10

Competing interests

The author declares that he has no competing interests.