Disagreement in physical activity assessed by accelerometer and self-report in subgroups of age, gender, education and weight status.

Background: The purpose of this study is to compare self-reported time (by questionnaire) and objectively measured time (by accelerometer) spent on physical activity at moderate (MPA) and vigorous intensity (VPA) in subgroups of age, gender, education and weight status.

Methods: In total, 236 adolescents (aged 12-18) and 301 adults (aged 22-40), completed the questionnaire and wore an accelerometer for two weeks.

Results: Adolescents reported exceptionally more time spent on MPA (mean difference 596 +/- 704 min/wk) and VPA (mean difference 178 +/- 315 min/wk) than was assessed objectively by the accelerometer.