PURPOSE: Consistency in physical activity is crucial to acquire maximum health benefits. The current physical activity (PA) recommendation for adolescents is to accrue 420 minutes of PA a week. The purpose of this study was to examine proximal changes in adolescent physical activity. METHODS: Adolescents in a freshman high school health class answered Exercise Vital Sign (EVS) questions over the course of nine weeks. Minutes of PA per week was calculated by multiplying days of PA by minutes of PA. Participants were then categorized as meeting (≥420 minutes/week) or not meeting (<420 minutes per week) current PA guidelines. An alluvial diagram was created to perform exploratory visual analysis of the magnitude and variability in meeting and not meeting PA trajectories across the four time points. RESULTS: Of the twenty-five who participated, 21 had EVS data at four points in time. The average PA across all time points was 312 ± 272 minutes per week. PA between the time points ranged from 245-355 minutes per week. 14% of adolescents always met PA recommendations and 48% never met PA recommendations. 10% of adolescents missed the recommended PA only once, 24% missed twice, and 5% missed PA recommendations three times. From Time Point 1 to Time Point 4 the percentage of adolescents who did not meet PA recommendations were 57%, 71%, 71%, and 62%, respectfully. DISCUSSION: The benefits of regular, consistent exercise include improved mood, physical fitness and sleep quality as well as a decreased risk of chronic diseases. Adolescence is a key developmental stage because developed health behaviors often translate into adulthood. A large majority (86%) did not meet PA guidelines at least once during the study. There may be differences between those who never meet and those who sometimes meet the recommended PA levels. Individual Trajectories of Meeting and Not Meeting PA Guidelines over Four points in Time