To (i) validate a recently proposed questionnaire tool for the simple assessment of physical activity (PA) in pre-school children by comparison with accelerometry and heart-rate recordings; and (ii) extend the tool by adding more questions to improve validity and to refine the classification from two to three categories (PA low, medium, high).

Baseline data of an intervention evaluation study.

Pre-school children.

Children were categorized as either physically active or non-active, based on their parents’ answers to the five-item questionnaire. Activity and heart rate were recorded for 6 d (Actiheart device; CamNtech, Cambridge, UK). Nightly sleeping periods were removed and mean accelerometry counts (MACT), time spent in moderate-to-vigorous intensity physical activity (MVPA) and time spent in sedentary behaviour (SB) were computed. In a second step, additional questions that improved validity were added, resulting in an extended seven-item questionnaire.

For 748 (90·4 %) of the participating children aged 2·3–6·7 years, the questionnaires were filled out sufficiently for classification. Children classified as physically active showed 9·6 % higher MACT (P < 0·0003), spent more time in MVPA and insignificantly less time in SB. Using the extended questionnaire, children with PA classified as medium (reference: low) showed 11·0 % more MACT, spent 11·8 % more time in MVPA and 4·8 % less time in SB. Children with PA classified as high showed 16·9 % more MACT, spent 20·2 % more time in MVPA and 7·2 % less time in SB.

With validated PA questionnaires for pre-school children lacking, the proposed questionnaire might be a reasonable option to include for PA assessment in epidemiological studies where more elaborate measurements are unavailable.