Protocol of the "As du Coeur" study: a randomized controlled trial on physical activity maintenance in cardiovascular patients.

Background: Although the benefits of supervised physical activity programs in cardiac rehabilitation have been well documented, the amount of physical activity often drops quickly after the end of the supervised period. This trial (registered as ISRCTN77313697 ) will evaluate the effectiveness of an experimental intervention based on habit formation theory applied to physical activity maintenance.
Methods/design: Cardiovascular patients (N = 56) will be individually randomized into two groups. Two supervised physical activity (SPA) sessions per week will be offered to the first group for 20 weeks. Progressively autonomous physical activity (PAPA) will be offered to the second group as follows: 10 weeks of the same supervised program as the SPA group followed by 10 more weeks in which one supervised session will be replaced by a strategy to build and sustain the habit of autonomous practice of physical activity. The primary outcome is the amount of physical activity measured by the International Physical Activity Questionnaire (IPAQ; Craig et al., Med Sci Sport Exercises 35(8):1381-95, 2003). To compensate for the limited capacity to recruit subjects, multiple IPAQ measurements will be made (at T0, T5, T7, T9 and T12 months after the start of the intervention) and analyzed using the mixed model approach. We will also assess changes in physical and physiological indicators, automaticity of the physical activity behavior, motivation and quality of life. Last, we will assess the cost-effectiveness for each type of program.
Discussion: If proven to be effective, the PAPA intervention, which requires fewer supervised sessions, should provide a cost-effective solution to the problem of physical activity maintenance in cardiac rehabilitation.