Fatigue: Biomedicine, Health & Behavior - Volume 2, Issue 4, 2014

Volume 2, Issue 3, 2014

 * If only I were paramecium too! A case for the complex, intelligent system of anticipatory regulation in fatigue "Abstract - Background: Fatigue is a common term used to describe feelings of tiredness along with observations of reduced physical effort in both health and disease. The study of fatigue has centered mainly on understanding its putative causes. Recently (1990s), fatigue has been researched with an expanded view encompassing its potential origins and purposes in human physiology. Purpose: This review will explore and consider different fatigue models which could assist in the evolving understanding of this human condition. Methods: In this narrative review, Medline and Google Scholar were initially utilized to identify studies and texts documenting the developing understanding of fatigue. Following this, key words were used to locate investigations describing reactions to external stimuli in basic and complex organisms. The term anticipatory regulation was entered to locate studies which evaluated this construct in both health and disease. Results: This review shifts the focus of the fatigue paradigm from the catastrophe model, which emphasizes peripheral energy supply and demand, to the anticipatory regulation model, which focuses on a central regulatory process that anticipates energy demands and makes adjustments to accommodate future demand. The potential for this model to be used to explain the fatigue process in both health and disease is also discussed with respect to specific pathologies. Conclusion: There is now a body of evidence indicating that fatigue may represent a process of anticipatory regulation for maintaining homeostasis."
 * Fatigue in neurological disorders: a review of self-regulation and mindfulness-based interventions "Abstract - Background: Fatigue is prevalent in neurological disorders and is associated with increased disability and mortality rates. Currently, clinical assessment and management of fatigue is difficult as underlying mechanisms remain poorly understood. Purpose: This narrative review integrates models of pathological fatigue with the concepts of self-regulation and mindfulness. Findings from clinical trials testing the efficacy of mindfulness-based interventions (MBI) for fatigue in neurological disorders are also reviewed. Methods: A search of Medline and PsycINFO databases was conducted using “fatigue,” “neurological disorders,” “exercise,” “self-regulation,” and “mindfulness” search terms to identify articles published from 1980 to the present. Only articles reporting on fatigue relevant clinical outcomes were included in the review of trials testing MBI. Results: Recent definitions and models of pathological fatigue suggest that neurological disorders might instigate maladaptive changes in self-regulation leading to difficulties in sustaining movement and disproportionate levels of perceived effort. MBI might be effective in the management of fatigue since mindfulness training is thought to promote self-regulation by developing attention control and cognitive and emotional flexibility. Findings from a small number of clinical trials provide limited support for the efficacy of mindfulness-based interventions for fatigue in neurological disorders. Conclusion: Given the prevalence and debilitating effect of fatigue in neurological conditions, further research is needed to investigate the potential role of maladaptive self-regulation in the aetiology of this condition. Further research is also needed to test the efficacy of MBI including large randomised controlled trials with active control conditions and which directly assess changes in mindfulness along with fatigue."
 * Perspectives on biochemical and neurosensory mechanisms for exercise-induced pain inhibition "Abstract - Purpose: To outline the potential mechanisms and experimental limitations for exercise-induced pain inhibition. Methods: Investigations that applied physical exertion to evoke changes in experimental pain response were reviewed and evaluated for inclusion. Previous research studies were appraised in a historical context to explicate pain measurement and to expound the prospective underlying mechanisms for exercise-induced pain inhibition. Results: The function of pain-modulatory systems during exercise may have evolved to extend performance and survival. Previous studies have implicated the modulation of pain through activation of descending inhibitory pathways and attenuation of ascending pain-related signaling during and after physical exercise. Central and peripheral release of compounds, such as endorphins and endocannabinoids, as well as baroreceptor inhibitory effects on pain have been postulated in exercise-induced pain inhibition. Inhibition of pain with exercise appears to show adaptation, as revealed by enhanced tolerance to pain with exercise training. Conclusion: The diminution of pain with physical exercise has been associated with mediation of pain-related signaling at central and peripheral sites. Application of this finding could extend into human performance and the therapeutic treatment of pain."
 * Fatigue across the CNS spectrum: a clinical review "Abstract - Fatigue is reflected in a broad array of symptoms that can be particularly impactful in patients with central nervous system (CNS) disorders. Fatigue symptoms can present as core components of the underlying CNS disorder, as part of co-morbid medical conditions, as secondary to psychosocial stressors or physical or mental exertion, and/or secondary to the medications used to treat the disorders. The complex, multi-factorial etiology of fatigue symptoms can obscure the assessment and complicate the treatment intervention for the underlying primary CNS disorder. In this narrative clinical review, we focus on identification, assessment, and adjunctive pharmacological treatment of fatigue symptoms across five distinct CNS disorders. Given the potential impact of fatigue on function and quality of life, it is important to address this symptom as part of a comprehensive evaluation."