Pain inhibition and postexertional malaise in myalgic encephalomyelitis/chronic fatigue syndrome: An experimental study

Abstract

Abstract. Van Oosterwijck J, Nijs J, Meeus M, Lefever I, Huybrechts L, Lambrecht L, Paul L (Vrije Universiteit Brussel, Brussels; Artesis University College Antwerp, Antwerp; University Hospital Brussels, Brussels; Private Practice For Internal Medicine, Ghent ⁄ Aalst; CVS Contactgroep, Bruges; Belgium; and University of Glasgow, Glasgow, UK). Pain inhibition and postexertional malaise in myalgic encephalomyelitis ⁄ chronic fatigue syndrome. J Intern Med 2010; 268: 265-278.Objectives. To examine the efficacy of the pain inhibitory systems in patients with myalgic encephalomyelitis ⁄ chronic fatigue syndrome (ME ⁄ CFS) during two different types of exercise and to examine whether the (mal)functioning of pain inhibitory systems is associated with symptom increases following exercise.Design. A controlled experimental study.Setting and subjects. Twenty-two women with ME ⁄ CFS and 22 healthy sedentary controls were studied at the Department of Human Physiology, Vrije Universiteit Brussel.Interventions. All subjects performed a submaximal exercise test and a self-paced, physiologically limited exercise test on a cycle ergometer. The exercise tests were undertaken with continuous cardiorespiratory monitoring. Before and after the exercise bouts, subjects filled out questionnaires to assess health status, and underwent pressure pain threshold measurements. Throughout the study, subjects' activity levels were assessed using accelerometry.Results. In patients with ME ⁄ CFS, pain thresholds decreased following both types of exercise, whereas they increased in healthy subjects. This was accompanied by a worsening of the ME ⁄ CFS symptom complex post-exercise. Decreased pressure thresholds during submaximal exercise were associated with postexertional fatigue in the ME ⁄ CFS group (r = 0.454; P = 0.034).Conclusions. These observations indicate the presence of abnormal central pain processing during exercise in patients with ME ⁄ CFS and demonstrate that both submaximal exercise and self-paced, physiologically limited exercise trigger postexertional malaise in these patients. Further study is required to identify specific modes and intensity of exercise that can be performed in people with ME ⁄ CFS without exacerbating symptoms.

Role of Infection and Neurologic Dysfunction in Chronic Fatigue Syndrome

“…138 A controlled study comparing patients with CFS to sedentary healthy control volunteers during two types of controlled exercise (submaximal, and self-paced physiologically limited) found that pain thresholds following exercise increased in controls, but decreased in patients with CFS. 139 These studies suggest, but do not prove, a physiologic basis for the postexertional malaise reported by a high fraction of patients with CFS.…”

Exercise-Induced Hypoalgesia Profile in Rats Predicts Neuropathic Pain Intensity Induced by Sciatic Nerve Constriction Injury

“…9,26,58,64 However, questions were raised regarding the effect of exercise on patients with faulty modulation systems. 33,65,66 The goal of this study was to investigate the predictive value of the EIH profile on pain intensity in a rat model of nerve injury. Extrapolating from studies on CPM, we hypothesized that rats with less efficient EIH would develop more severe pain following nerve injury.…”

The role of clinical guidelines for chronic fatigue syndrome/myalgic encephalomyelitis in research settings

“…[14] Moreover, neurological testing has been suggested for structural and functional abnormalities [15] as well as sleep studies. [16] Also, monitoring for PENE, [17,18] and tilt table tests for the presence of orthostatic intolerance [19] have been listed. The International Consensus Primer is the first to include profiling of the immune system, particularly for reduction in Natural Killer cell function, [20] a possible increase in cytoxicity, [21] and for signs of intestinal dysbiosis.…”