Stages of change model for excercise : stage selection dependent on rater

The stages of change model has been advocated to assess readiness for adoption and/or maintenance of physical activity. Population-based studies using the model have relied on self-report for initial stage classification. Whether the self-selected stage would agree with that selected by investigators has not been firmly established. The purpose of this study was to asses agreement between self-selected and criteria-selected stage classifications. Subjects were volunteers screened for participation in a supervised exercise program (N=93; 48 men; 45 women) with mean age = 48.5 ± 14 years. Subjects selected a stage category using the published descriptions of the stages, but were also classified by two criteria using information about either physical activity (Criteria A) or exercise (Criteria B) habits.Stage differences (contemplators thru maintenance) were assessed using a Chi Squared analysis. Significant differences were observed between self-selected and both criteria A and B (Chi Squared = 81.2 & 78.0 respectively; P <0.0001) selected stages. In addition, there was a significant difference between the two criteria classifications(Chi Squared = 185; P<0.0001). These results demonstrate that stage selection varies as a function of the rater, as well as whether it is physical activity or exercise being contrasted within the model stages. Accurate classification is important for designing more efficacious exercise intervention, thus these results identify a problem related to stage selection in the stages of change model.