The relationship between estimates of total and central body fat with fibromyalgia pain, fatigue and overall impact has not been fully described. We aimed to assess the individual and combined association of body fat (total and central) with pain, fatigue and the overall impact in fibromyalgia women; and to study the possible mediation role of physical fitness in these associations.
A total of 486 fibromyalgia women with a mean (standard deviation) age of 52.2 (8.0) years participated. Pain was measured with self-reported measures and algometry, whereas fatigue with the Multidimensional Fatigue Inventory. The impact of fibromyalgia was measured with the Revised Fibromyalgia Impact Questionnaire (FIQR) total score. Total and central body fat were assessed by means of bioelectrical impedance and waist circumference, respectively. The Functional Senior Fitness Test battery and the handgrip strength test were used to assess physical fitness.
Total and central body fat were positively associated with pain- and fatigue-related measures and the FIQR total score (β from 0.10 to 0.25; all, p < 0.05). A combined effect of total and central body fat was observed on pain (FIQR and 36-item Short-Form Health Survey), general and physical-related fatigue and FIQR total score (all, overall p < 0.05), so that the group with no total and central obesity had more favourable results than those with total and central obesity. Cardiorespiratory fitness partially mediated (between 22-40% of the total effect) the associations between total and central body fat with pain, general fatigue, physical fatigue and reduced activity, and largely mediated (80%) the association of central body fat with the FIQR total score.
Physical fitness might potentially explain the association between obesity and fibromyalgia symptoms.