PT - JOURNAL ARTICLE AU - Kapteyn, Arie AU - Banks, James AU - Hamer, Mark AU - Smith, James P AU - Steptoe, Andrew AU - van Soest, Arthur AU - Koster, Annemarie AU - Htay Wah, Saw TI - What they say and what they do: comparing physical activity across the USA, England and the Netherlands AID - 10.1136/jech-2017-209703 DP - 2018 Jun 01 TA - Journal of Epidemiology and Community Health PG - 471--476 VI - 72 IP - 6 4099 - http://jech.bmj.com/content/72/6/471.short 4100 - http://jech.bmj.com/content/72/6/471.full SO - J Epidemiol Community Health2018 Jun 01; 72 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.