This study identified inconsistencies in physical activity (PA) reported at screening and baseline of a 6-month health promotion intervention and explored how these inconsistencies influenced intervention effectiveness in African American and Hispanic women. Participants completed a telephone screener to determine eligibility for a PA intervention. Inactive participants (≤90 minutes of PA/week) were invited to a baseline assessment, where they completed the International Physical Activity Questionnaire, measuring work, transportation, gardening/housework, and leisure-time PA. Women returned after 6 months to complete an identical post-intervention assessment. Despite being screened as inactive, baseline Questionnaire data indicated that 85.0% of participants (N = 274, M age = 44.6 years, M body mass index = 34.8 kg/m2) were active (>90 minutes of PA/week). Women who reported any work-related PA were 20.9 times more likely to be active at baseline than those who did not (p < .001). Participants who were inactive at both screening and baseline reported greater increases in domestic and gardening PA and total PA from baseline to postintervention (ps < .05). Overweight/obese ethnic minority women may misreport being physically inactive during screening if specific questions about type of PA are not included. Post hoc analyses controlling for screening inaccuracies may improve effectiveness of PA interventions and help intervention programs reach women who may benefit the most.
Keywords: health disparities; intervention study; minority health; physical activity; research design.