Self-regulatory fatigue in chronic multisymptom illnesses: scale development, fatigue, and self-control.

Background: Self-regulatory capacity involves ability to regulate thoughts, emotions, and behavior. Chronic multisymptom illnesses such as fibromyalgia and chronic fatigue syndrome are accompanied by numerous challenges, and have recently been associated with self-regulatory fatigue (SRF). Chronic multisymptom illnesses are also frequently associated with physical fatigue, and through development of a scale measuring SRF, the current study aimed to examine how SRF can be distinguished from physical fatigue. The study also sought to distinguish SRF from self-control.

Methods: Two self-regulation researchers developed 30 items related to self-regulatory capacity. These items were distributed to patients (n = 296) diagnosed with chronic multisymptom illness together with validated measures of physical fatigue and self-control. A principal factor analysis was employed to examine factor structures, identify inter-item relationships, and aid in scale development.

Results: The final proposed scale consisted of 18 items measuring self-regulatory capacity (SRF-18) with cognitive, emotional, and behavioral SRF components. Internal consistency and reliability was acceptable (Cronbach's á = 0.81). The final scale was moderately correlated with self-control (r = -0.48) and highly correlated with physical fatigue (r = 0.75), although more so with emotional (r = 0.72) and mental (r = 0.65) than physical (r = 0.46) fatigue components.

Conclusion: The current study suggests a new scale for measurement of SRF in chronic multisymptom illness. Although cross-validation studies are necessary, such a scale may contribute to a better understanding of the concept of self-regulation and the role of SRF in chronic illness. Although related to physical fatigue and self-control, the results point to SRF as a distinct construct.