Intensity-specific validity and reliability of the Japan Public Health Center-based prospective study-physical activity questionnaire.

The Japan Public Health Center-based prospective study- physical activity questionnaire (JPHC-PAQ) was originally developed and validated for total physical activity (total PA). However, it is uncertain whether JPHC-PAQ could also estimate intensity-specific physical activity. The present study aims to evaluate the validity and reliability of intensity-specific physical activity by the JPHC-PAQ against 24-hour activity records (24 h-R). One-hundred and ten participants were chosen from those who had enrolled in the JPHC cohort. Time spent for total PA and intensity-specific physical activity, i.e. moderate (MPA), vigorous (VPA) and moderate-to-vigorous physical activity (MVPA) was estimated by JPHC-PAQ. In addition, the volume of PA was calculated by time of each activity multiplied by intensity of activity. For validity assessment, estimated physical activities were compared with 24 h-R. For reliability evaluation, a retest was conducted 3-6 months after the first survey was answered. Moderately strong correlation between JPHC-PAQ and 24 h-R was observed for total PA estimations (Spearman's rho = 0.672). In addition, moderate correlations were found for MPA (activity time: rho = 0.345, activity volume: rho = 0.300) and MVPA (activity time: rho = 0.563, activity volume: rho = 0.672). Whereas, little association was found for VPA time and volume. As for reliability, moderately strong correlation was found for both total and intensity-specific physical activity in the test-retest (rho = 0.482-0.745). In addition to total PA, the JPHC-PAQ showed acceptable validity and reliability for intensity-specific physical activity, especially in estimating MVPA and MPA.