The Anti-Fatigue Effect of Moderate Cooling: The Evidence, Physiological Mechanisms, and Possible Implications for the Prevention or Treatment of CFS pp. 57-88
Authors: Nikolai A. Shevchuk, Molecular Radiobiology Division, Department of Radiation Oncology, Virginia Commonwealth University School of Medicine, Richmond, VA
Abstract: At least eight studies published since 1962 suggest that moderate cooling of the body (in most cases by means of cold water) can reduce fatigue in healthy subjects and in some groups of patients: fibromyalgia, multiple sclerosis, and rheumatoid arthritis. To date, there have been no studies on the effectiveness of this approach in CFS, aside from a pilot study in Australia, which used contrast water therapy in combination with nutritional and exercise interventions. Psychostimulant medications, the anti-fatigue therapy with the strongest level of clinical evidence for a number of disorders, do not appear to be effective in CFS patients. The possible mechanisms of the anti-fatigue effect of cooling may involve the following: A) A reduction of the total level of serotonin in the brain, as evidenced by direct measurements in laboratory animals and by a drop of the plasma prolactin level in human subjects; this would be consistent with reduced fatigue according to ―the serotonin hypothesis of central fatigue.‖ B) Activation of stress-response pathways such as the hypothalamic-pituitary-adrenal axis and sympathetic nervous system. C) Systemic analgesia and reduced muscle pain in particular; this may be mediated by a spike in the plasma level of beta-endorphin, an opioid peptide, as well as by the gate control effects of sensory stimulation by cold water. D) Activation of components of the brainstem arousal system, such as raphe nuclei and locus ceruleus (most likely associated with activation of the sympathetic nervous system). This diffuse modulatory system controls the sleep/wake cycle and minor lesions correlate with severe chronic fatigue. E) Possible activation of relevant dopaminergic pathways in the brain, such as those projecting to the striatum. F) Activation of the thyroid and increased metabolic rate.