Purpose: To test the ability of the theory of planned behavior (TPB) in predicting the stage of change for physical activity promotion by mental health professionals.
Design: Six-month prospective questionnaire study.
Setting: One mental health trust in the East Midlands, United Kingdom.
Subjects: Three hundred ninety-four mental health professionals (men, n = 131; women, n = 263) of an initial sample of 477 participated in the study (83% response rate).
Measures: Attitudes, subjective norms, intentions, perceived behavioral control, and stage of change were measured at the first wave of data collection. Stage of change was also assessed 6 months later. Data were analyzed using structural equation modeling.
Results: Intention and stage of change were successfully predicted from TPB variables. Overall, 27% of the variance in self-reported stage of promoting physical activity was explained by the model. Sixty-one percent of the variance in intention to promote physical activity was explained. When included, past behavior was the strongest predictor of both intention and stage of change and attenuated all other path coefficients. Past behavior improved the predicted variance in intention by 11% and stage by 6%.
Conclusions: The TPB variables of attitude, subjective norms, perceived behavioral control, and intention predict stage of change of physical activity promotion in a health care setting. However, promoting physical activity in the past had a sizable effect on predicting subsequent promotion. Due to unequal distribution across stages, the stage model's application to understanding the behavior of health professionals may be limited.