Reduced pressure pain thresholds in response to exercise in chronic fatigue syndrome but not in chronic low back pain: An experimental study

Abstract

Objective: The aims of this study were to examine: (i) baseline pressure pain thresholds in patients with chronic fatigue syndrome and those with chronic low back pain compared with healthy subjects; (ii) the change in mean pain threshold in response to exercise; and (iii) associations with exerciseinduced increase in nitric oxide. Participants: Twenty-six patients with chronic fatigue syndrome suffering of chronic pain, 21 patients with chronic low back pain and 31 healthy subjects. Methods: Participants underwent a submaximal aerobic exercise protocol on a bicycle ergometer, preceded and followed by venous blood sampling (nitric oxide) and algometry (hand, arm, calf, low back). Results: Patients with chronic fatigue syndrome presented overall lower pain thresholds compared with healthy subjects and patients with chronic low back pain (p < 0.05). No significant differences were found between healthy subjects and patients with chronic low back pain. After submaximal aerobic exercise, mean pain thresholds decreased in patients with chronic fatigue syndrome, and increased in the others (p < 0.01). At baseline, nitric oxide levels were significantly higher in the chronic low back pain group. After controlling for body mass index, no significant differences were seen between the groups at baseline or in response to exercise. Nitric oxide was not related to pain thresholds in either group. Conclusion: The results suggest hyperalgesia and abnormal central pain processing during submaximal aerobic exercise in chronic fatigue syndrome, but not in chronic low back pain. Nitric oxide appeared to be unrelated to pain processing.

Lack of Endogenous Pain Inhibition During Exercise in People With Chronic Whiplash Associated Disorders: An Experimental Study

“…Impaired endogenous pain inhibition during exercise and exacerbation of symptoms following physical exertion or ''post-exertional malaise'' have been previously reported chronic pain conditions characterized by central sensitization (eg, chronic fatigue syndrome and fibromyalgia). 3,15,17,19,30,36,41,48 The increase in symptoms was not proportional to the decrease in PPTs, as there were no associations found between the degree of exercise-induced analgesia and the degree of symptom exacerbation, which is in accordance with our current understanding of central sensitization (ie, that symptom changes do not correspond to what happens in the tissues).…”

“…All data were analyzed using IBM SPSS Statistics v. 19.0 for Windows (IBM Corporation, Somers, NY). Normality of the variables was tested with the KolmogorovSmirnov test and appropriate descriptive statistics were calculated.…”

“…10 This is due to the activation of strong opioidergic and other pain inhibitory mechanisms (descending inhibition) orchestrated by the central nervous system. 14,21 Impaired endogenous pain inhibition during exercise and postexertional symptom exacerbations have been reported in chronic pain conditions characterized by central sensitization such as chronic fatigue syndrome 3,19,36,48 and fibromyalgia. 15,17,30,41 However, no data regarding the response of people with chronic WAD to exercise are available.…”

Heart rate variability in patients with fibromyalgia and patients with chronic fatigue syndrome: A systematic review

“…However, the majority of CFS patients also suffer chronic widespread pain or comorbid FM and pain inhibition is even so failing [50,51], but the pain component was not assessed or mentioned in the CFS studies. This underlines again the lack of comparative studies.…”

Hypoalgesia After Exercise and the Cold Pressor Test is Reduced in Chronic Musculoskeletal Pain Patients With High Pain Sensitivity

“…26 Other studies have reported hypoalgesia in patients with musculoskeletal pain during the cold pressor test 15,27 and after exercise. 24,28 These results indicate that although impaired pain inhibition is common in patients with chronic pain, the pain-inhibitory systems might still be functioning in some patients. The efficacy of paininhibitory pathways has previously been linked to the clinical pain intensity, 29,30 pain catastrophizing, 31 age, 32 and sex.…”