Abstract
BackgroundMotor problems are reported by patients with fibromyalgia (FM). However, the mechanisms leading to alterations in motor performance are not well understood. In this study, upper limb position control during sustained isometric contractions was investigated in patients with FM and in healthy controls (HCs).MethodsFifteen female FM patients and 13 HCs were asked to keep a constant upper limb position during sustained elbow flexion and shoulder abduction, respectively. Subjects received real-time visual feedback on limb position and both tasks were performed unloaded and while supporting loads (1, 2, and 3 kg). Accelerations of the dominant upper limb were recorded, with variance (SD of mean position) and power spectrum analysis used to characterize limb position control. Normalized power of the acceleration signal was extracted for three frequency bands: 1–3 Hz, 4–7 Hz, and 8–12 Hz.ResultsVariance increased with load in both tasks (P < 0.001) but did not differ significantly between patients and HCs (P > 0.17). Power spectrum analysis showed that the FM patients had a higher proportion of normalized power in the 1–3 Hz band, and a lower proportion of normalized power in the 8–12 Hz band compared to HCs (P < 0.05). The results were consistent for all load conditions and for both elbow flexion and shoulder abduction.ConclusionFM patients exhibit an altered neuromuscular strategy for upper limb position control compared to HCs. The predominance of low-frequency limb oscillations among FM patients may indicate a sensory deficit.
Highlights
Motor problems are reported by patients with fibromyalgia (FM)
All subjects performed the required tasks without difficulties, and the FM patients did not report any significant change in shoulder/ neck pain from before to after the testing (P = 0.15)
There was a tendency that the FM patients had a higher percentage of the total power covered by the three frequency bands; this was only significant for the elbow flexion task when supporting 1 kg (FM, 94.2%, standard deviation (SD) 3.9 vs healthy controls (HCs), 86.5%, SD 11.5, P =0.031) and 2 kg (FM, 92.3%, SD 5.3 vs HCs, 84.3%, SD 11.7, P =0.036)
Summary
Motor problems are reported by patients with fibromyalgia (FM). The mechanisms leading to alterations in motor performance are not well understood. Upper limb position control during sustained isometric contractions was investigated in patients with FM and in healthy controls (HCs). FM patients commonly report motor problems such as poor balance and coordination, clumsiness, tremors [5], and slowness of movements [6]. Motor problems are mainly self-reported, and few studies have investigated the characteristics of motor performance in FM patients. Studies of motor control in FM patients have shown a lower rate of change in the electromyographic mean spectral frequency of biceps brachii during sustained elbow flexion [7] and an altered activation pattern of different regions within the trapezius muscle during sustained shoulder elevation [8]. Gerdle and co-workers [9] have found
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