The total number of MET-minutes per week reported on the questionnaire correlated modestly with the main criterion measure of total weekly activity counts measured by the accelerometer (r = 0.41, p = 0.023). However, time spent in both moderate and vigorous physical activity was over reported on the questionnaire. The mean difference compared to accelerometer was 546.63 minutes per week (95% CI 217.1 to 871.2 minutes) for moderate and 295.33 minutes per week (95% CI 88.08 to 502.6 minutes) for vigorous activity. The tool's sensitivity to detect individuals with insufficient physical activity to derive a health benefit was low (9.5%), however specificity was high (100%).