Comparison and calibration of 24-hour physical activity recall in adult population

Abstract This study compared and calibrated metabolic equivalents (METs) per day from 24-hour physical activity recall (24hPAR) with accelerometry. A sub-sample of 74 adults of both sexes, residents of Brasilia, Brazil, from a larger study had same day measurements of accelerometry and 24hPAR data. METs values were assessed by accelerometry (7 consecutive days of use) and by 24hPAR (minimum of one and maximum of 2 per person). A script was written in the R statistical software to analyse the recall and accelerometer data. The script ran a simple linear regression to visualize the relationship between total METs/day for the two methods and to execute the recall measurement error correction. Most of participants were female (54.1%), with at least university graduate (94.6%) and mean age of 34.8 years (±11.83). The correlation coefficient obtained between 24hPAR and accelerometer was r = 0.55, considered moderate and significant (p < 0.001). A majority of the participants (77%) underestimated METs values compared to accelerometry when answering the questionnaire. Calibration of 24hPAR allowed us to approximate MET values to the accelerometer. The calibration equation to correct total METs/day for measurement error is (total 24hPAR METs/day - 10.6)/0.619. The 24hPAR is a decent tool to assess PA level in large adults' samples. However, compared with accelerometer, it underestimates METs values, which can be corrected with the use of the calibration equation provided in this study.