Comparison of Self-reported versus Accelerometer-Measured Physical Activity

The International Physical Activity Questionnaire (IPAQ) is one of the most widely used questionnaires to assess physical activity (PA). Validation studies for the IPAQ have been executed, but still there is a need for studies comparing absolute values between IPAQ and accelerometer in large population studies.

Purpose:
To compare PA and sedentary time from the self-administered, short version of the IPAQ with data from ActiGraph accelerometer in a large national sample.

Methods:
A total of 1,751 adults (19-84 years) wore an accelerometer (ActiGraph GT1M) for seven consecutive days and completed the IPAQ-S. Sedentary time, total physical activity and time spent in moderate to vigorous activity were compared in relation to sex, age and education.

Results:
Men and women reported on average 131 (SE:4) min[BULLET OPERATOR]day-1 less sedentary time compared with the accelerometer measurements. The difference between self-reported and measured sedentary time and vigorous intensity PA was greatest among men with a lower education level and for men aged 65 years and older. Although men reported 47% more moderate to vigorous physical activity (MVPA) compared to women, there were no differences between sexes in accelerometer-determined MVPA. Accelerometer-determined moderate PA was reduced from 110 to 42 min[BULLET OPERATOR]day-1 (62%) when analyzed in blocks of 10 min (P<0.0001) compared to one minute blocks. The main correlation coefficients between self-reported variables and accelerometer measures of physical activity were between 0.20-0.46.

Conclusions:
The participants report through IPAQ-S more vigorous PA and less sedentary time compared with the accelerometer. The difference between self-reported and accelerometer-measured MVPA increased with higher activity and intensity levels. Associations between the methods were affected by sex, age and education, but not body mass index.