Validating motivational readiness for exercise behavior with adolescents.

The stages of motivational readiness as conceptualized by the Transtheoretical Model have been widely used among adult samples to assess readiness for adopting exercise behavior. To date, little research has been conducted using a staging framework with adolescent samples. There is a need for validation of the staging framework prior to a substantial amount of research with this age group. The current article presents two studies assessing stage and reported exercise behavior (Study 1: n = 819; M age = 15.0 years, SD = 1.2; 51% men; Study 2: n = 184; M age = 18.6 years, SD = .5; 45% men). As hypothesized in both studies, reported exercise consistently varied as a function of stage classification; those in earlier stages of readiness reported less exercise than those in later stages. Staging algorithms showed good sensitivity to detect reported exercise; however, specificity was distinctly better with the algorithm that used a specific activity criterion and immediate intention, as opposed to irregular behavior, in defining the preparation stage. Results support the validity of the staging framework for measuring motivational readiness for exercise behavior among North American adolescents.