Autonomic nervous system profile in fibromyalgia patients and its modulation by exercise: a mini review

Abstract

This review imparts an impressionistic tone to our current understanding of autonomic nervous system abnormalities in fibromyalgia. In the wake of symptoms present in patients with fibromyalgia (FM), autonomic dysfunction seems plausible in fibromyalgia. A popular notion is that of a relentless sympathetic hyperactivity and hyporeactivity based on heart rate variability (HRV) analyses and responses to various physiological stimuli. However, some exactly opposite findings suggesting normal/hypersympathetic reactivity in patients with fibromyalgia do exist. This heterogeneous picture along with multiple comorbidities accounts for the quantitative and qualitative differences in the degree of dysautonomia present in patients with FM. We contend that HRV changes in fibromyalgia may not actually represent increased cardiac sympathetic tone. Normal muscle sympathetic nerve activity (MSNA) and normal autonomic reactivity tests in patients with fibromyalgia suggest defective vascular end organ in fibromyalgia. Previously, we proposed a model linking deconditioning with physical inactivity resulting from widespread pain in patients with fibromyalgia. Deconditioning also modulates the autonomic nervous system (high sympathetic tone and a low parasympathetic tone). A high peripheral sympathetic tone causes regional ischaemia, which in turn results in widespread pain. Thus, vascular dysregulation and hypoperfusion in patients with FM give rise to ischaemic pain leading to physical inactivity. Microvascular abnormalities are also found in patients with FM. Therapeutic interventions (e.g. exercise) that result in vasodilatation and favourable autonomic alterations have proven to be effective. In this review, we focus on the vascular end organ in patients with fibromyalgia in particular and its modulation by exercise in general.

Strengthening Exercises Improve Symptoms and Quality of Life but Do Not Change Autonomic Modulation in Fibromyalgia: A Randomized Clinical Trial

“…It was recently demonstrated that serotonin is increased after 20 weeks of aerobic training, compared with FLEX training, in FM patients [35]. However, the mechanism underlying how exercise modifies the HRV remains unknown [10], [40], [41]. Until recently, studies have suggested that exercise influences HRV through neural stimulus by heart sympatho-vagal balance readjustments, with increased vagal modulation and reduced sympathetic modulation [42].…”

Exercise prevents development of autonomic dysregulation and hyperalgesia in a mouse model of chronic muscle pain

“…The marked decrease in RMSSD indicates decreased heart rate variability reflects loss of parasympathetic modulation. Abnormalities in autonomic regulation occur in people with CMP, with substantial heterogeneity between studies that is attributed to co-morbidities, subgroups with different underlying mechanisms, methodological issues, medication effects, age, or sex [42;61]. Despite the heterogeneity, decreased heart rate variability and baroreflex sensitivity are found consistently in people with CMP [14;16;19;26;32;54;69;72;73].…”

“…CMP has been associated with autonomic dysfunction in humans, albeit with substantial heterogeneity of dysfunction among subjects [42;61]. Decreases in heart rate variability and baroreflex sensitivity, and abnormal autonomic responses to physiological challenges have been most consistently observed in people with chronic pain [16;19;26;32;54;69;72;73].…”

“…In fact, regular physical activity reduces the risk of both heart disease [4] and development of chronic pain [44;45]. Whilst some studies have shown that exercise can correct autonomic dysfunction in fibromyalgia, others do not show beneficial effects [27;42]. It is possible that different types of exercise, different intensities of exercise, or different durations of exercise underlie these conflicting data.…”

Teste cardiopulmonar de exercício em pacientes com fibromialgia juvenil

“…A disfunção do sistema nervoso autônomo (também chamada de distúrbio autonômico ou disautonomia) tem sido associada à fisiopatologia da fibromialgia em pacientes adultos 12,13,14 .…”