## 4 Discussion  
In this study we used a simple mediational model to clarify the role of perceptions regarding walking held by women with fibromyalgia and the role they play in adhering to a pattern recommended as a way to decrease adverse symptoms. We found that although participants viewed walking as an intense activity, it was positively associated with objective walking through the influence of beliefs regarding their abilities about physical exercise (self-efficacy). Overall, the hypothesized model paths were supported, and model fits were uniformly acceptable. Based on the stability of the results found, the clinical implications of the present study are discussed below. The first step we undertook was to explore possible mismatches between the subjects' perceptions of walking and the objective measures of their walking pattern. Our results clearly suggest a significant association between subjective measures of vigorous activity and the objective measure of walking. Although previous studies have reached the same conclusions with smaller fibromyalgia or chronic pain samples [50; 51; 52; 53], our interest was also focused on determining which psychological and physical factors may explain the differences between subjectivity and observable performance in patients' walking behavior. On this topic, the previous literature on fibromyalgia shows that the discordance between assessment measures can be explained by problems in central pain processing. This fosters the persistent occurrence of chronic widespread pain, among other common symptoms of fibromyalgia such as fatigue and cognitive problems [54; 55] along with the presence of anxious and/or depressive symptoms [28; 29]. Therefore, we set out to explore the possible effect of physical and emotional symptoms on the association between the subjective (self-reported) and the objective (accelerometer-based) measures of walking. The correlation results showed significant relationships between the measurements provided by the IPAQ-s questionnaire and the accelerometer. Specifically, of the two types of intensity provided by the self-report, it was the perception of intense activity that was significantly associated with walking, considering that the latter is a moderate-intensity activity following the indications of [PERSON] et al. [25] regarding physical exercise guidelines in fibromyalgia. These data suggest the suitability of both instruments for evaluating the physical activity of chronic pain patients, since it is not only the amount of exercise performed that is important, but the subjective vision that patients have about exercise as well. In this context, the perception of the intensity of a given activity could have a negative or positive impact on adherence to this guideline as part of the recommended treatment for fibromyalgia. In view of the above, the following question may be asked: what factors influence women with fibromyalgia to perceive moderate activity as intense? According to the contributions offered by [PERSON] et al. [31], the physical symptoms typical of the disease influence the patients' subjective evaluation of physical exercise. Even memory and attention problems have an impact on patients not remembering accurately the type of exercise they have performed [56], and therefore self-report measurements may be biased. Our results show that depressive symptoms correlate both with perceived moderate-intensity physical activity (IPAQ-s) and with the objective measure of walking (accelerometers), while in the latter case (accelerometers) the association with cognitive problems must also be included. Based on these preliminary analyses, the model we suggest considers these symptoms as possible factors influencing the predictive effect of intensity perception on objective walking behavior. In line with our hypothesis, the perception of vigorous intensity in the activity predicted the walking pattern (accelerometers) carried out for a week.