Reliability and Validity of the Global Physical Activity Questionnaire for Portuguese Adults.

The Global Physical Activity Questionnaire (GPAQ) has been used often to assess physical activity (PA) patterns. However, the European Portuguese version of this instrument has not been validated. We aimed to validate the self-administered GPAQ, version 2, (GPAQv2) for Portuguese adults. We included 32 participants in a pilot study of a Portuguese adaptation of the test and 108 participants in an assessment of their PA patterns and sedentary behavior (SB) through the GPAQv2. For its validation, we compared the GPAQv2 to the International PA Questionnaire-Long Form (IPAQ-LF) (concurrent validity) and the ActiGraph wGT3X-BT accelerometer (criterion validity). We evaluated PA and SB at baseline and after seven consecutive days. Test-retest reliability with the Kappa test (k) and the Intraclass Correlation Coefficient (ICC) ranged from strong to almost perfect (k: 0.864-0.976) and from moderate to excellent (ICC: 0.56-0.994), respectively. Concurrent validity, assessed by Spearman's Correlation Coefficient, was moderate to substantial (rho: 0.471-0.680), and there was fair to substantial criterion validity (rho: 0.226-0.672). Bland-Altman plots showed that the GPAQv2 overestimated vigorous and moderate to vigorous PA and underestimated moderate PA. The largest difference values were related to SB, since the GPAQv2 underestimated sitting time. In sum, we found the GPAQv2 to have acceptable validity and reliability for assessing PA and SB patterns, and we recommend its use for Portuguese adults.