Upper limb position control in fibromyalgia
Journal article, Peer reviewed
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http://hdl.handle.net/11250/2386742Utgivelsesdato
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Sammendrag
Background: Motor 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).
Methods: Fifteen 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.
Results: Variance 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.
Conclusion: FM 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.