Objective: This study aimed to translate the physical activity (PA) questions in the WHO Health Behaviour in School-aged Children (HBSC) survey questionnaire into Japanese (HBSC-J) and to examine their validity.

Methods: Participants were the 5th grade primary school students (70 students aged 11.3 ± 0.3 years: 10.6-11.9 years). The questionnaire was translated into Japanese and refined through the processes of preliminary test, backtranslation into English and discussion with authors of original version. Validity was determined by comparing the data with accelerometer estimates. To assess the validity of the PA questions, we used Spearman rank correlation between the questions and the objectively measured moderate-to-vigorous PA (MVPA) or vigorous PA (VPA) by the accelerometer. Comparisons of the mean objective time in MVPA between students classified as a self-reported days at least 60 minutes/day of MVPA in ≥ 5 days students and < 5 days students according to the HBSC-J were carried out using unpaired t tests.

Results: A statistically significant positive correlation was found between MVPA and the number of days with at least 60 minutes/day of MVPA (ρ = 0.339). In addition, statistically significant positive correlations were found between VPA and the HBSC-J questions looking at the frequency of VPA (ρ = 0.515), and between VPA and the HBSC assessment of VPA duration (ρ = 0.400). Moreover, the MVPA time with the ≥ 5 days tended to be greater than that in students with less than 5 days.

Conclusion: The results suggest that the questionnaire is valid for evaluating MVPA and VPA patterns in Japanese primary school students.