The relation of self-rated measures of physical activity to multiple risk factors of insulin resistance syndrome (IRS) was examined in African American (n = 409) and white (n = 1,011) young adults aged 20 to 38 years enrolled in the Bogalusa Heart Study. Physical activity was assessed in terms of work activity, leisure-time activity, television watching, and video game playing by a questionnaire. Waist circumference, blood pressure, total to high-density lipoprotein cholesterol ratio, and insulin resistance index showed a consistent inverse trend with leisure-time activity (P < 0.01) and a positive trend with hours of inactivity (P < 0.01) after adjusting for age, race, and sex. An inverse relationship was seen between leisure-time activity and mean number of risk factors (>75th percentile for age, race, and sex) (P < 0.001), whereas a positive relationship was seen with hours of inactivity (P < 0.001). Moderately to very active individuals versus inactive individuals had a reduced relative risk of having > or =3 risk factors (P < 0.05); conversely, excess hours of inactivity increased the relative risk (P < 0.05). Thus, leisure-time activity and hours of inactivity are important predictors of multiple cardiovascular risk variables of IRS in young adults.