Abstract
The purpose of this current study was to examine the influence of cardiovascular health knowledge on dietary and physical activity changes in 15-17 year olds with elevated blood pressure. The sample consisted of 167 adolescents randomized into one of three treatment conditions (minimal, moderate, or intense). Each adolescent completed a fitness test (peak VO2), 24-hour dietary recall, 7 Day Activity Recall (kilocalories expended per day), Self-efficacy Questionnaire, and Stages of Change Questionnaire every three months. The Health Knowledge Assessment was given at baseline and at post-intervention. Classical test theory, confirmatory factor analysis, and item response theory frameworks were applied to examine psychometric properties of the Health Knowledge Assessment. Structural equation modeling was used to examine the change in health behaviors and the relationship with health knowledge, self-efficacy, and readiness for change. The 34-item Health Knowledge Assessment had good internal consistency and the items loaded onto a single factor at pretest and posttest. Furthermore, there was a good distribution of easy, moderate, and hard items at pretest, but additional hard items were needed at posttest. There were no treatment condition differences in level of health knowledge at pretest. The intense condition had significantly higher health knowledge than the minimal and moderate conditions at posttest; level of health knowledge for the moderate condition was significantly higher than the minimal condition at posttest. Level of nutrition knowledge at posttest was not associated with any of the dietary intake variables nor was level of exercise knowledge associated with the two physical activity variables at post-intervention. However, there was a marginally significant association between level of nutrition knowledge and nutrition self-efficacy at posttest. Nutrition self-efficacy and nutrition readiness for change at posttest were also associated with a decrease in sugar consumption at post-intervention. Implications of this study suggest that a cardiovascular health intervention for adolescents with elevated blood pressure, consisting of group sessions and/or individual sessions over the course of three to six months, was effective in terms of increasing cardiovascular health knowledge, self-efficacy, and readiness for change. Nonetheless, the role that health knowledge plays in health behavior change needs to be further examined.