Physical activity was assessed at baseline using a brief questionnaire covering occupation and recreational activity [12;13]. Although an index of physical activity derived from this questionnaire had previously been validated against repeated objective measures of activity in the UK and in the Netherlands [13], no validation study has been conducted in any other country. Therefore, a study to test the validity of the questionnaire in European populations was conducted in InterAct, including 100 men and 100 women comparable to those originally recruited into the EPIC study from each participating InterAct country, with an objective measurement of physical activity by individually calibrated combined heart rate and movement sensing [14]. Results from this validation study will be published as a separate report.
