## 4 Discussion  
The current investigation proposed to assess the effect of fatigue, the impact of fibromyalgia, and the fear of movement on self-efficacy (specifically on that for physical function). Based on findings from the current study and previous research [10; 12; 17], self-efficacy largely affects physical activity levels. Thus, given the relationship between self-efficacy and physical activity, the variables able to predict self-efficacy would also have a relevant influence on physical activity levels. However, the results showed that only the self-efficacy for physical function was significantly different according to the physical activity levels, while the self-efficacy for coping with symptoms and for pain management was not. This finding supports the model developed by [PERSON], [PERSON], [PERSON], [PERSON], [PERSON], and [PERSON] [12], where the self-efficacy for physical activity was a predictor for the actual physical activity levels, with the mediation role of pain avoidance and activity avoidance patterns in the case of light physical activity. The association between self-efficacy and physical activity levels has been previously suggested in the framework of the social cognitive theory [39]. This is because self-efficacy is a motivational determinant of behavior that affects the perception of a goal as feasible or not, and when physical activity is the desired behavior, self-efficacy is the key factor as a predictor of achievement among chronic pain patients [11]. In other populations like, for example, children or fragile older adults, this relationship has also been observed by finding that children who had better physical conditions and less fragile older adults showed higher levels of perceived self-efficacy [40; 41]. The current study supports the well-known relationship between self-efficacy and desired behavior by finding differences in the self-efficacy for physical function according to the physical activity levels evaluated using the IPAQ tool. Interestingly, differences were only found between patients with low levels of physical activity and the rest of the participants, with no differences between those with medium and high levels. This could be due to the low number of participants with high levels of physical activity, which is in line with the usual low proportion previously reported [42]. This achievement could provide important information for exercise professionals, attempting to promote greater self-efficacy in patients during the sessions, thus making it easier to increase their levels of physical activity. Based on the well-known relationship between self-efficacy and physical activity and the previously mentioned model developed by [PERSON], [PERSON], [PERSON], [PERSON], [PERSON], and [PERSON] [12], the current study aimed to identify which variables could affect self-efficacy for physical activity among women with fibromyalgia. Among all fibromyalgia symptoms, pain is still considered the main one, but fatigue has emerged as a relevant \"forgotten symptom\" [43]. Accordingly, a prior investigation indicated that fatigue and physical function may be more closely related to an active lifestyle  
Figure 1: Multivariable mediation results. than pain in women with fibromyalgiagia [44]. The current study supports the observed relevance of fatigue by identifying direct and significant correlations with the total impact of the disease and the function evaluated using FIQ-R, as well as with the self-efficacy for symptoms, pain, and physical activity. Therefore, perceived fatigue levels should not be omitted when trying to explain why people with fibromyalgia achieve the desired levels of physical exercise or not. Apart from fatigue, another variable that can influence the perception of the capacity of patients with fibromyalgia to conduct physical activity is the fear of movement. This variable is often related to functional capacity, a fear of falling, and the impact of fibromyalgiagia [45].