Activity rhythms and clinical correlates in fibromyalgia

Abstract

The primary aim of this study was to evaluate activity rhythms in fibromyalgia syndrome (FMS) and their association with FMS-related symptoms. We hypothesized that stronger and more consistent activity rhythms would be associated with reduced symptom severity and presentation in FMS. Two hundred ninety-two patients with FMS (mean age = 45.1 ± 11.1; 272 women) provided a 7-day actigraphy recording and responses to questionnaires addressing degree of pain, fatigue, mood, and physical impairment. Using a simple cosine model, we extracted Amplitude (activity range), Phi (time at maximum), Mesor (mean activity), and their variabilities (across days) from each participant's actigraphy. The clinical and actigraphic measures were operationally independent. There was a significant canonical relationship between activity rhythm parameters and clinical FMS measures (r = 0.376, R 2 = 0.14, P < 0.001). The set of Mesor, Amplitude, and Phi activity parameters remained associated with clinical measures when controlled statistically for both demographics and activity variability (P < 0.001). Each activity parameter provided unique discrimination of the clinical set by multivariate test (P = 0.003, 0.018, and 0.007 for Amplitude, Phi, and Mesor, respectively). These results revealed that better pain, fatigue, mood, physical impairment, and sleep outcomes were associated with higher activity range and more rhythmicity (Amplitude), increased mean activity (Mesor), and with earlier timing of peak activity (Phi). Exploratory analyses revealed significantly worse sleep for individuals with low Amplitude and more delayed Phi.

Characterizing Behavioral Activity Rhythms in Older Adults Using Actigraphy

“…The main advantage of the simple cosinor model is that it provides a parsimonious model that requires only three parameters ( Table 1). The outcome variables derived from this approach are mesor (midline estimating statistic of rhythm), amplitude (height of the cosine peak), and phi (also called phase or acrophase, the timing of the peak of the rhythm) [26]. Results using this approach tend to focus on amplitude and phi with less emphasis on the mesor.…”

“…Sensors 2020, 20, x FOR PEER REVIEW 4 of 17 mesor (midline estimating statistic of rhythm), amplitude (height of the cosine peak), and phi (also called phase or acrophase, the timing of the peak of the rhythm) [26]. Results using this approach tend to focus on amplitude and phi with less emphasis on the mesor.…”

<p>Impact of transcutaneous electrical nerve stimulation on sleep in chronic low back pain: a real-world retrospective cohort study</p>

“…The study authors hypothesized that TENS activates the hypothalamic suprachiasmatic nuclei, which regulates biological clocks. Abnormal rest–activity patterns have been reported in chronic pain conditions including fibromyalgia,75 painful diabetic neuropathy,76 and knee osteoarthritis with insomnia 77…”

<p>Remote Analgesic Effects Of Conventional Transcutaneous Electrical Nerve Stimulation: A Scientific And Clinical Review With A Focus On Chronic Pain</p>

“…163 The study authors hypothesized that TENS activates the hypothalamic suprachiasmatic nuclei, which regulates biological clocks. Interestingly, abnormal restactivity patterns have also been reported in chronic-pain conditions, including fibromyalgia, 164 painful diabetic neuropathy, 165 and knee osteoarthritis with insomnia. 166 It is possible that some widespread effects of TENS result from modulating physical or emotional functions that are adversely impacted by chronic pain.…”