Validity and reproducibility of a physical activity questionnaire in women.

Abstract

To determine the validity and reproducibility of a self-administered physical activity questionnaire that assesses the frequency, intensity, and duration of recreational, household, and occupational activity in women. The questionnaire was administered by mail twice to 131 participants 1 yr apart. During this interval, participants completed four 1-wk activity logs corresponding to different seasons throughout the year. The intraclass correlation coefficients used to measure reproducibility were 0.82 for total activity, 0.79 for moderate activity, 0.86 for vigorous activity, 0.80 for recreational activity, and 0.73 for household activity. The distribution of activity scores was similar between the questionnaires and the average of the four logs, indicating the participants' ability to incorporate seasonal variation into their recall on a questionnaire. The correlations between the questionnaire-based activity scores and log-based activity scores, indicating validity, were 0.26 for total activity, 0.15 for moderate activity, and 0.52 for vigorous activity. Women younger than age 50 tended to have higher validity scores than women aged 50 yr and older (r = 0.31 vs r = 0.19, respectively, for total activity). These data indicate that this physical activity questionnaire is reproducible and provides a useful measure of current activity, particularly vigorous activity, over a 1-yr period.