Background/Purpose:  The highest prevalence of severe fatigue in rheumatic diseases is observed in FM¹. Physical fitness and subjective well-being have been suggested as resilience resources that can help to deal with FM symptomatology^2,3. The present study aimed to examine: (i) the independent association of overall physical fitness and subjective well-being with fatigue, and (ii) the combined association of overall physical fitness and subjective well-being components with fatigue in FM.

Methods: We used data from the al-Ándalus project, which is a population-based cross-sectional study. A total of 420 women with FM, who met the 1990 ACR FM criteria, were included in the present study. Fatigue was assessed with Multidimentional Fatigue Inventory. Physical fitness was measured with the Senior Fitness Test battery. The scores of each physical fitness test were transformed to standardized z-scores ([value-mean]/standard deviation) to compute an overall physical fitness score. Subjective well-being was assessed with two questionnaires: the Positive and Negative Affect Schedule (for positive affect and negative affect) and Satisfaction with Life Scale (for satisfaction with life).

Results: Based on preliminary analyses to identify potential confounders, all analyses of the present study were adjusted by age and body fat percentage. All partial correlations between overall physical fitness, positive affect, negative affect, and satisfaction with life and fatigue dimensions were significant (all, p≤.004). Linear regression models showed that: (i) overall physical fitness was independently associated with general fatigue and physical fatigue (both, p<.001), (ii) positive affect was independently associated with lower scores at all fatigue dimensions (all, p<.001), (iii) negative affect was independently associated with reduced motivation and mental fatigue (p<.001 and p=.01, respectively), and (iv) satisfaction with life was independently associated with mental fatigue (p=.046). Analyses of covariance showed statistically significant combined associations of overall physical fitness and positive affect with general and physical fatigue (all, p<.001).

Conclusion: Findings of the present study highlight the significance of the association of physical fitness and positive affect with fatigue of women with FM. Further research, using longitudinal data, testing the causality of the present findings is required. References: ¹Overman, CL et al., Clin Rheumatol. 2016;35(2):409-15. ²Estévez-López, F et al., Qual Life Res. 2015;24(8):1865-73. ³Sturgeon, JA and Zautra AJ. Curr Pain Headache Rep. 2013 Mar;17(3):317. Funding: The Spanish Ministry of Economy and Competitiveness (I+D+i DEP2010-15639, I+D+i DEP2013-40908-R, BES-2014-067612, and BES-2011-047133) and of Education (FPU12/00963 and FPU13/01088).

ACR Meeting Abstracts - https://acrabstracts.org/abstract/independent-and-combined-association-of-overall-physical-fitness-and-subjective-well-being-components-with-fatigue-in-fibromyalgia/