This study is the first phase of the formative research recommended in the Theory of Planned Behavior for the development of an intervention. Our aims are to identify modal beliefs about the performance of an exercise pattern in people with fibromyalgia, to test the items designed for direct evaluation of the predictive constructs and to explore their relationships with the behavior. We assessed 46 women with fibromyalgia. Content analysis showed more positive than negative consequences related to the performance of exercise guidelines (behavioral beliefs). Families and friends are the important referents (normative beliefs) and we identified facilitating and inhibiting factors in the performance of exercise behavior related to aspects of fibromyalgia (control beliefs) such as pain, fatigue and emotional state. The subjective norm scale showed the lowest internal consistency (a= .78). The results confirmed the sedentary lifestyle of the participants (previous behavior: Mean=3.67; rank=1-7) although they also suggested that participants intended to perform the behavior (Mean=5.67). The relationships between constructs are coherent with the theory, and support the relevance of applying it to the selected behavior and population.
