[Validity and reliability of the Work-related Physical Activity Questionnaire for assessing intensity-specific...

We developed the Work-related Physical Activity Questionnaire (WPAQ) to measure occupational physical activity, including sedentary behavior and sedentary breaks (interruptions of prolonged sedentary behavior), during work. This study aimed to examine the WPAQ's reliability and criterion validity using an accelerometer.

To examine criterion validity, 97 full-time factory workers (male: 89.7%) wore a triaxial accelerometer while working and completed the WPAQ. The questionnaire inquired about participants' normal work activities and the proportion of sitting, standing, walking, and heavy labor engaged in during work. In calculating time spent in each behavior, the proportion of each occupational activity was multiplied by the total minutes of work. Duration of uninterrupted sitting time was also measured. For reliability, the same questionnaire was administered twice (median test-retest interval: 9 days) to another convenient sample of 54 participants. Spearman's ρ was used to assess validity and intraclass correlation coefficients (ICCs) and Cohen's kappa with quadratic weighing were used to assess reliability.

The criterion validity of occupational sitting time measured by the WPAQ was moderate (Spearman's ρ for sedentary behavior: 0.69) based on comparison with accelerometer data. Significant positive correlations were found for standing (ρ = 0.66) and walking (ρ = 0.39) between the WPAQ and accelerometer data, though not for heavy labor. A moderate but significant correlation (ρ = 0.27) was found for sedentary breaks. Test-retest reliability for all items was adequate (ICC = 0.59-0.79 for occupational sedentary behavior and physical activities, and Cohen's kappa with quadratic weighting = 0.84 for sedentary breaks).

The WPAQ has acceptable properties for measuring workers' activities, including sedentary breaks. Reduced physical activity, increased time spent in sedentary behaviors, and fewer sedentary breaks during working time are all associated with adverse health outcomes. Though some occupational exposure to these activities might be unavoidable, the WPAQ may be a practical tool for assessing them.