RT Journal Article SR Electronic T1 What they say and what they do: comparing physical activity across the USA, England and the Netherlands JF Journal of Epidemiology and Community Health JO J Epidemiol Community Health FD BMJ Publishing Group Ltd SP jech-2017-209703 DO 10.1136/jech-2017-209703 A1 Arie Kapteyn A1 James Banks A1 Mark Hamer A1 James P Smith A1 Andrew Steptoe A1 Arthur van Soest A1 Annemarie Koster A1 Saw Htay Wah YR 2018 UL http://jech.bmj.com/content/early/2018/04/09/jech-2017-209703.abstract AB Background Physical activity (PA) is important for maintaining health, but there are fundamental unanswered questions on how best it should be measured.Methods We measured PA in the Netherlands (n=748), the USA (n=540) and England (n=254), both by a 7 day wrist-worn accelerometer and by self-reports. The self-reports included a global self-report on PA and a report on the frequency of vigorous, moderate and mild activity.Results The self-reported data showed only minor differences across countries and across groups within countries (such as different age groups or working vs non-working respondents). The accelerometer data, however, showed large differences; the Dutch and English appeared to be much more physically active than Americans h (For instance, among respondents aged 50 years or older 38% of Americans are in the lowest activity quintile of the Dutch distribution). In addition, accelerometer data showed a sharp decline of PA with age, while no such pattern was observed in self-reports. The differences between objective measures and self-reports occurred for both types of self-reports.Conclusion It is clear that self-reports and objective measures tell vastly different stories, suggesting that across countries people use different response scales when answering questions about how physically active they are.