[Stages of change for exercise behavior and self-efficacy for exercise among middle-aged adults]

The transtheoretical model of behavior change (TTM) has been used to account for how people change their health behavior. It was originally developed to explain or predict change in unhealthy addictive behavior (e.g., smoking), but recently the use of the TTM within the physical activity and exercise behavior domain has been proposed. In the present study, we examined its structure in this regard among middle-aged Japanese adults. In particular, the relationship between the stages of change for exercise behavior and self-efficacy was investigated. Firstly, a scale was developed to assess self-efficacy for exercise. Four hundred and sixty seven middle-aged adults completed questionnaires. As a result of stepwise variable selection procedure in exploratory factor analysis, a scale comprising 1 factor with 5 items was developed. Psychometric analyses revealed that this scale had high reliability and validity. Secondly, a cross-sectional investigation was conducted to examine the relationship between stage of change and self-efficacy among middle-aged adults (n = 808) using a questionnaire approach. Significant associations were found between stage of change for exercise behavior classification and self-efficacy for exercise. Specifically, scores on self-efficacy of the subjects in the present study were less for those in a precontemplation stage and greater for those in maintenance compared to all other stages, and generally followed a linear pattern of change across the stages. Although the use of a cross-sectional research design and nonrandom sampling methods in the present study limit interpretation, the similarity of these results to those in the previous literature suggests that the relationship between stages of change for exercise behavior and self-efficacy for exercise holds across different age groups and cultures. By accurately understanding these relationships, health promotion professionals may be able to improve physical activity and exercise promotion efforts.