Validity of items assessing self-reported number of breaks in sitting time among children and adolescents
Background: Sedentary behaviour guidelines recommend that individuals should regularly break up sitting time. Accurately monitoring such breaks is needed to inform guidelines concerning how regularly to break up sitting time and to evaluate intervention effects. We investigated the concurrent validity of questionnaire items assessing number of breaks in sitting time among children and adolescents. Methods: Fifty-seven children and adolescents self-reported number of breaks from sitting taken at school, while watching TV and during other screen time activities. Participants also wore an activPAL monitor to objectively assess the number of sitting time breaks (frequency/hour). Concurrent validity was assessed using Spearman rank correlations. Results: Self-reported number of breaks/hour at school showed good concurrent validity (ρ=0.676). Results were moderate to good for self-reported number of breaks/hour while watching TV (ρ range: 0.482 to 0.536) and moderate for self-reported number of breaks/hour in total screen time (ρ range: 0.377 to 0.468). Poor concurrent validity was found for self-reported number of breaks/hour during other screen time activities (ρ range: 0.157 to 0.274). Conclusions: Only the questionnaire items about number of breaks at school and while watching TV appear to be appropriate for further use in research focussing on breaks in prolonged sitting among children and adolescents.