Associations of smart device apps with and without a perceived self-efficacy component in a physical activity context with BMI.

Smart device apps can be used to promote physical activity, decrease sedentariness, or increase self-efficacy to get active in college students, possibly reducing their obesity risk. This study assessed associations of college students' smart device use with body mass index (BMI), expecting associations between physical activity parameters and self-efficacy with BMI, moderated by app type. In an online survey, app data of a week from student's devices, weight, height, physical activity, and self-efficacy to get active were collected from 120 students. Apps were categorized "physical activity," "physical activity with a self-efficacy component," or "unrelated." Use time of physical activity apps is not associated with BMI, while self-efficacy app time show negative and unrelated app time positive associations. Self-efficacy may be an important component in app design for obesity risk reduction of college students. Test economy was low, which is why future studies need to concentrate on better data extraction methods.