Effects of a self-efficacy intervention on exercise: The moderating role of diabetes and cardiovascular diseases

The paper examines the influence of a brief tailored intervention on exercise levels and self-efficacy beliefs in the context of participants' health status. We hypothesised that the effects of a self-efficacy intervention targeting more frequent exercise would be larger among people with diabetes or cardiovascular diseases (CVD), compared to the effects of the intervention among individuals without such diseases. The treatment was tailored to participants' self-efficacy and was delivered by e-mail. Data from 187 adults were collected at two measurement points, with a 6-month follow-up. Participants reported their exercise frequency and self-efficacy scores, along with several social-cognitive variables, such as risk perception and intentions. Besides the influence of the intervention on exercise and self-efficacy, we found that the treatment effects were moderated by diabetes or CVD: Participants with those illnesses benefited from the intervention, compared to people without such diagnosis. Among participants with CVD or diabetes the effects of the intervention on behavior were mediated by changes in efficacy beliefs. The results indicated that a parsimonious treatment may contribute to change in exercise over the longer term, in particular among individuals with a disease related to the respective behavior. Changes in behavior may be explained by changes in respective beliefs.