Reliability and validity of the occupational physical activity questionnaire

Introduction: Few questionnaires have been designed for wide-scale, population-based surveillance of occupational physical activity (PA) behaviors. Purpose: This study was conducted to determine the test-retest reliability and validity of the Occupational Physical Activity Questionnaire (OPAQ) designed to assess the usual weekly duration of occupational sitting or standing, walking, and heavy labor activities. Methods: Analyses were based on a convenience sample of 41 adults (13 men, 28 women) (mean +/- SD, 38.8 +/- 9.9 yr) who worked in a broad range of occupations. Intraclass correlation coefficients (ICC) were used to evaluate the 2-wk test-retest reliability of the OPAQ. Spearman correlations were used to assess criterion (occupational PA record, Actigraph) and construct (cardiorespiratory fitness, percent body fat) related validity. Convergent validity with the current Behavioral Risk Factor Surveillance System (BRFSS) occupational PA question was evaluated with the kappa coefficient. Results: The 2-wk test-retest reliability coefficients for the OPAQ hours per week ranged from an ICC of 0.55 to 0.91. Fair-to-substantial criterion validity was observed for like activities on the OPAQ and a detailed 7-d occupational PA record for sitting or standing (r = 0.37), walking (r = 0.74), and heavy labor activity (r = 0.31). OPAQ walking was related to PA record moderate-intensity PA (r = 0.41), Actigraph occupational light-intensity counts (r 0.41), and Actigraph total counts (r = 0.44). Associations observed between the OPAQ and submaximal exercise heart rate or percent body fat were low (r = -0.17 to 0.32). Convergent validity displaying the ability of the OPAQ to correctly identify participants who performed mostly sitting or standing, mostly walking, or mostly heavy labor at work was substantial [kappa = 0.71 (95% CI = 0.49, 0.94)]. Conclusions: The test-retest reliability and validity of the OPAQ are similar to other established occupational PA questionnaires. This preliminary study supports the use of the OPAQ in research and surveillance settings.