Accuracy and inequalities in physical activity research – Authors' reply
Authors: Regina Guthold, Gretchen A Stevens, Leanne M Riley, Fiona C Bull
Journal: The Lancet Global Health (2019)

We thank Jelle Van Cauwenberg and colleagues, Jean-Philippe Chaput, and Gary O'Donovan for their comments on our recent study, in which we analysed the prevalence of insufficient physical activity in 168 countries, and estimated regional and global trends. The large variations in inactivity levels identified between countries—even within regions—suggest that influencing factors lie mostly at the national, subnational, or community level, where policies are needed to increase physical activity. The scope of our analysis limited further investigation of these influencing factors and intracountry inequalities. However, we agree with Jelle Van Cauwenberg and colleagues that social inequalities in physical activity need to be measured and adequately addressed in future policy and programming, to ensure equity of opportunities for participation.1WHOGlobal action plan on physical activity 2018–2030. More active people for a healthier world. World Health Organization, Geneva2018Google Scholar The results of our analysis were based on self-reported physical activity. Chaput argues that this method of assessment might underestimate the magnitude of the physical inactivity crisis, since previous research from Canada2Colley RC Garriguet D Janssen I Craig CL Clarke J Tremblay MS Physical activity of Canadian adults: accelerometer results from the 2007 to 2009 Canadian Health Measures Survey.Health Rep. 2011; 22: 7-14PubMed Google Scholar showed that inactivity levels were higher when measured with accelerometers compared with self-report. However, such differences might not be observed in other settings. To date, only a few studies—the majority of which were done in high-income countries—have compared self-reported and objectively measured physical activity data. Furthermore, standard analysis protocols and cutoffs are scarce for objective activity data.3Wijndaele K Westgate K Stephens SK et al.Utilization and harmonization of adult accelerometry data: review and expert consensus.Med Sci Sports Exerc. 2015; 47: 2129-2139Crossref PubMed Scopus (163) Google Scholar In view of the poor availability and representativeness of objectively measured physical activity data at present, we believe that national and global estimates of physical inactivity must be based on self-report data, and that our estimates provide useful and actionable information on physical inactivity. Existing burden of inactivity calculations,4Lee IM Shiroma EJ Lobelo F et al.Effect of physical inactivity on major non-communicable diseases worldwide: an analysis of burden of disease and life expectancy.Lancet. 2012; 380: 219-229Summary Full Text Full Text PDF PubMed Scopus (5010) Google Scholar current global recommendations,5WHOGlobal recommendations on physical activity for health. World Health Organization, Geneva2010Google Scholar and other national guidelines on physical activity for health, including the US 2018 Physical Activity Guidelines62018 Physical Activity Guidelines Advisory Committee2018 Physical Activity Guidelines Advisory Committee Scientific Report.http://health.gov/paguidelines/second-edition/report/pdf/pag_advisory_committee_report.pdfDate accessed: October 24, 2018Google Scholar largely rely on self-reported physical activity data. Although we agree that future use of device-based measures of physical activity is likely, since these types of data are absent in most countries worldwide, the best available evidence must be used to support and guide action to increase physical activity levels. As O'Donovan rightly mentions, three surveys done in Colombia met the inclusion criteria of our study. The two larger surveys, the 2005 National Nutrition Survey and the 2010 STEPwise approach survey in Santander, both showed that the prevalence of insufficient activity was more than 50% in many age and sex strata, which has since been confirmed in the 2015 National Nutrition Survey.7MinsaludEncuesta Nactioan de la Situatión Nutricional ENSIN.http://www.nocomasmasmentiras.org/wp-content/uploads/2017/12/Resultados-ENSIN-2015.pdfDate: 2015Date accessed: December 22, 2018Google Scholar We encourage further publication and trend analysis in Colombia to contribute to improved estimates. We applaud the efforts in Colombia and other Latin American nations, and elsewhere, to increase population levels of physical activity. We declare no competing interests. Accuracy and inequalities in physical activity researchI agree with Regina Guthold and colleagues1 and Ding Ding in the accompanying Comment2 that large-scale interventions are needed to increase physical activity. Colombia has been labelled the least active country in the world3 and Latin America and the Caribbean had some of the highest levels of insufficient physical activity in the analysis by Guthold and colleagues.1 However, far from being inactive, Colombia and Latin America are pioneers in large-scale physical activity interventions.4 Full-Text PDF Open AccessAccuracy and inequalities in physical activity researchIn their Article on global estimates and trends of insufficient physical activity in adults, Regina Guthold and colleagues (October, 2018)1 included data from nearly 2 million participants who were representative of 96% of the global population. A key finding was that about a quarter (27·5%) of adults worldwide do not get enough physical activity to meet current public health guidelines. However, this estimate was based on self-reported questionnaires and probably misrepresents the true burden of physical inactivity around the world. Full-Text PDF Open AccessAccuracy and inequalities in physical activity researchRegina Guthold and colleagues1 should be congratulated on their rigorous efforts to harmonise and analyse physical activity data from 358 surveys across 168 countries. The Article highlights global patterns of physical inactivity. We agree with the authors' call to prioritise and scale up policy to increase population levels of physical activity, but we feel that their analysis overlooks important social inequalities in physical activity that need to be taken into account by policy and research. Full-Text PDF Open Access