Misalignment or Motivation? A Cluster Analysis Approach to Understanding Young Adolescent Physical Activity Trajectories in Summer Care Programs

Physical activity (PA) decreases during summer months, potentially leading to accelerated weight gain and increased depressive symptoms in adolescents. Summer care programs offer opportunities for PA promotion but understanding how different groups (based on initial perceived and objectively measured PA) respond to these programs is crucial for developing focused interventions. Adolescents (n = 47; mean age = 11.0 years; 51.1% female) who participated in an 8-week summer program wore ActiGraph GT9X accelerometers to measure moderate-to-vigorous physical activity (MVPA) at the beginning and end of the program. Self-reported PA was assessed using the Health Behavior in School-Aged Children survey. Both measures were then transformed into respective z-scores. K-means cluster analysis was performed to identify distinct groups based on device-measured and perceived PA at the beginning of summer. Changes in MVPA were compared across clusters using one-way ANOVA and post hoc Tukey’s HSD tests. Three clusters were identified: “High Accuracy Actives” (n = 17), “Underestimators” (n = 22), and “Overestimators” (n = 8). “Overestimators” showed the largest mean increase in MVPA (30.63 min/day), followed by “Underestimators” (17.76 min/day). “High Accuracy Actives” experienced a mean decrease in MVPA (−7.69 min/day). ANOVA revealed significant differences in MVPA change between clusters (F(2,44) = 4.93, p = 0.01). Summer care programs can positively impact adolescent PA, particularly for those who initially underestimate or overestimate their activity levels. However, strategies are needed to prevent declines among initially highly active participants. For example, adolescents who underestimate their activity levels may benefit from interventions focused on building self-efficacy and providing positive feedback, while those who overestimate might require educational components about PA guidelines and self-monitoring techniques.