Validity and reliability of a physical activity recall instrument among overweight and non-overweight men and women.

This study examined the validity and reliability of survey items measuring one-week recall of physical activity (PA) and examined differences by weight status. A sub-aim of the study was to objectively assess the intensity of activity that most closely matches self-report. A questionnaire was administered to adults twice, three days apart. It was again administered after subjects wore a MTI/CSA accelerometer for seven days (n = 118). Several metabolic equivalent (MET) thresholds were applied to the accelerometer data. Agreement between test and re-test estimates of sufficient physical activity for health benefits (150 min/week) was high (% agreement > 90%). Correlations (rho) between total reported PA (mins/day) and accelerometer data were 0.29 (p < 0.05) among men and 0.25 (p < 0.05) among women. Among men, self-reported duration of moderate PA (3-5.9 METS) and accelerometer data were significantly correlated (rho = 0.40, p < 0.01), with no differences by weight status. Among women, a significant relationship was found only for those who were not overweight (rho = 0.52, p < 0.001). A significant correlation between self-reported duration of vigorous PA (6+ METS) and accelerometer data was only found for overweight men (rho = 0.40, p < 0.05). When lower MET thresholds were applied to the accelerometer data, women's reported duration of moderate-intensity PA was most strongly correlated with moderate PA (accelerometer) defined as 2.0-5.9 METS (rho = 0.39, p < 0.01). The recall instrument provides a consistent measure of physical activity and validation coefficients were similar to those obtained for other physical activity recall questionnaires. However, the ability to measure PA by self-report may vary by weight status.