The symptoms of fibromyalgia are varied, including general muscle pain and pain at specific points (also called tender points), excessive fatigue, anxiety, depression, and some psychological problems that can have a negative impact on quality of life. Physical activity is a widely used option by health professionals to alleviate the effects of this syndrome. However, there is no clear information on the possible mediating role of physical activity in the relationship between fibromyalgia-related fatigue and quality of life. Therefore, this study aims to evaluate the relationship between fibromyalgia-related fatigue and quality of life, and to investigate the mediating role of physical activity in patients with this syndrome. Methods: In a cross-sectional study, 237 Portuguese women aged 28 to 75 years (M = 49.12; SD ± 8.87) and 117 Brazilian women aged 20 to 69 years (M = 46.72; SD ± 8.38) were recruited to participate in this study. These patients completed three valid and reliable questionnaires related to the assessment of fibromyalgia-related fatigue (MDF-Fibro-17), physical activity (IPAQ), and quality of life (SF-36). Results: Both samples had scores above the midpoint for all dimensions of fibromyalgia-related fatigue and scores below the midpoint for quality of life. Physical activity had no mediating effect in either sample, as the total indirect effect was not significant. Conclusions: Physical activity does not mediate the relationship between fatigue and quality of life. However, the results also show that the fatigue dimensions associated with fibromyalgia had a negative and significant association with physical and mental health indicators in both samples. Thus, patients with FM with higher scores on fatigue-related symptoms might suffer more from physical and mental health, both of which are related to quality of life.

Background and Objectives: Fibromyalgia are heterogeneous and differ from patient to patient; however, the most reported are general myalgia and at specific points associated with fatigue and certain psychological adversities. Physical activity can mitigate the effects of the symptoms. However, the associations between fibromyalgia-related fatigue, self-esteem, anxiety, depression, satisfaction with life and physical activity are unclear. Therefore, the aim of the present study was to understand the associations between these symptoms and whether there are differences between these associations across two distinct cultures. Materials and Methods: A total of 473 women aged between 28 and 75 years (M = 49.27; SD ± 8.28) completed five questionnaires about fibromyalgia-related fatigue, physical activity, anxiety, depression, self-esteem, and satisfaction with life. Results: Fibromyalgia-related fatigue was positively associated with depression and anxiety, depression and anxiety were negatively associated with self-esteem, self-esteem was positively associated with satisfaction with life, satisfaction with life was positively associated with physical activity and there were no differences in terms of the perceptions and associations of these variables between Portuguese and Brazilian patients. Conclusions: Our results showed the significant role of associations between these variables and a similarity in the perception and relationship of the variables between the two cultures.

The Multidimensional Daily Diary of Fatigue-Fibromyalgia-17 (MDF-fibro-17) is an instrument that measures the different components of fibromyalgia-related fatigue symptoms. The current study aims to examine the factor structure of the MDF-fibro-17 in a sample of Portuguese and Brazilian patients diagnosed with fibromyalgia. Additionally, a cross-cultural analysis was carried out on these samples to understand the multidimensional complexity of examining the different dimensions of fatigue in patients with different cultural backgrounds and how fibromyalgia impacts patients with this syndrome. A confirmatory factor analysis was performed to examine the psychometric properties of the measure. Additionally, a multigroup analysis was carried out on the samples of these two cultures to examine measurement invariance. In total, 209 Portuguese women aged between 21 and 75 years (M = 47.44; SD = 10.73) and 429 Brazilians women aged between 16 and 77 years (M = 46.51; SD = 9.24) participated in this study. The results revealed that the measurement model provided an acceptable fit to the data in both the Portuguese and Brazilian samples, also displaying acceptable convergent and discriminant validity. In addition, the model showed acceptable internal consistency and was invariant between cultures. In sum, the MDF-fibro-17 is a valid measure that offers a unique assessment of fatigue symptoms in Portuguese and Brazilian women with fibromyalgia.

Background and Objectives: The current literature demonstrates that different cultures have different perceptions of the symptoms of Fibromyalgia Syndrome (FM). The aim of the study was to explore the differences between Brazilian and Portuguese patients with FM in their fatigue experience and to measure the differences in the perception of fatigue according to age and duration of diagnosis. Materials and Methods: In total, 209 Portuguese women aged between 21 and 75 years old (M = 47.44; SD = 10.73) and 429 Brazilian women aged between 18 and 77 years old (M = 46.51; SD = 9.24) were recruited to participate in the present study. Participants filled out the items in the Multidimensional Daily Fatigue-Fibromyalgia-17 Diary (MDF-Fibro-17), a specific tool to measure the level of five components of FM-related fatigue. Results: The results showed a greater perception of all of the components of fatigue in the Brazilian sample. No significant differences were found related to the age and duration of FM diagnosis. Conclusions: Overall, there are significant differences in fatigue symptoms between Portuguese and Brazilian women with FM, suggesting that cultural and geographical differences should be considered when describing fatigue-related symptoms in women with FM.