Validation of physical activity instruments: Black Women's Health Study.

PURPOSE Few studies have reported on the validity of physical activity measures in African Americans. The present study was designed to determine the validity of a self-administered physical activity questionnaire (PAQ) that was used in a large prospective study of African American women in the United States against an accelerometer (actigraph), an objective assessment of movement, and a seven-day activity diary. METHODS The study was conducted among 101 women enrolled in the Black Women's Health Study (BWHS) cohort who resided in the Washington, DC, metropolitan area, representing 11.2% (101/900) of this sample. Physical activity levels were obtained from the parent BWHS PAQ (eg, 1997 and 1999) and repeated in the present study. This information entailed hours per week of participation in walking for exercise, hours per week of moderate activity (eg, housework, gardening, and bowling), and hours per week of strenuous activity (eg, basketball, swimming, running, and aerobics) during the previous year. The participants were required to wear actigraphs for seven days and then record their physical activities in their diaries (seven-day physical activity diary) during this time. The diaries were used to record the amount and pattern of daily energy expenditure. RESULTS Significant positive correlations were seen between the BWHS PAQ and the actigraph for total activity, r=.28; walking, r=.26; and vigorous activity, r=.40, P<.001. For the seven-day physical activity diary, the BWHS PAQ also demonstrated significant correlations for total (r=0.42, P<.01); moderate (r=.26, P<.05); and vigorous activities (r=.41, P<.01). CONCLUSIONS The BWHS PAQ is a useful measure of physical activity in the BWHS cohort and thus has utility in prospective epidemiologic research.