The feasibility of a theory-based self-regulation intervention in schools to increase older adolescents' leisure time physical activity behavior.

The purpose of this study was to test the feasibility of a theory-based self-regulation intervention to increase older adolescents' leisure time physical activity (LTPA) behavior. Forty-nine adolescents (M = 15.78 years; SD = 0.52; 31% female) from two schools agreed to participate. Participants were randomly assigned to the experimental or control arm at the school level. The experimental group (n = 24) underwent a brief self-regulation intervention for six weeks. The control group (n = 25) continued with standard classes. Intervention fidelity data was collected to assess feasibility. Outcome measures included self-reported LTPA behavior and self-regulation technique use. Intervention sessions were delivered as intended, participant attendance was high and compliance with intervention content was acceptable. The experimental group reported higher levels of LTPA behavior eight weeks post-intervention and increased use of self-regulation techniques. A brief theory-based self-regulation intervention delivered in a school-setting appears feasible and may increase LTPA behavior and self-regulation in adolescents.