An implementation intentions intervention, the use of a planning strategy, and physical activity after myocardial infarction.

The paper investigates the relations between involvement in an implementation intention intervention programme, frequency of the use of a self-regulatory physical activity planning strategy, and moderate physical activity among patients who had suffered myocardial infarction (MI). It examines whether effects of the implementation intention intervention on behavior change was mediated by change in the use of a planning strategy. A total of 114 patients from central and northern Poland took part in the study after their first uncomplicated MI. Data were collected individually at approximately 1 week after MI (Time 1), 2 weeks after short-term rehabilitation (about 8 weeks after MI: Time 2), and 8 months after MI (Time 3). After data collection at Time 2, patients were randomly assigned to the control group or the intervention group. Patients who participated in the implementation intention intervention maintained the same number of sessions of moderate physical activity at 8 months after MI (Time 3) as at 2 weeks after rehabilitation (Time 2). By contrast, patients from the control group performed significantly fewer sessions of moderate physical activity at Time 3, compared to Time 2. The intervention resulted in the more frequent use of a planning strategy at 8 months after MI. Change in the frequency of the use of a planning strategy completely mediated effects of the intervention on change in physical activity. Only patients who participated in the implementation intention intervention and increased their use of a planning strategy adhered to the recommended three or more sessions of moderate physical activity per week.