Surface EMG of the lumbar part of the erector trunci muscle in patients with fibromyalgia

Objective To determine differences supposed in EMG parameters of the erecto r trunci region between patients with fibromyalgia and healthy subjects dur ing defined investigation situations. Methods During sitting and standing in upright position surface EMG (SEMG)f rom 15 subjects with fibromyalgia and 10 healthy controls was performed usi ng a 16-channel technique where the electrodes were applied in a well-defin ed grid pattern (gain 5000, 3 db points at 5 Hz and 700 Hz respectively). S EMG quantification was done by Fourier algorithm using 512 measurement poin ts for calculation. Results An increased EMG amplitude could be recorded during rest in fibromy algia patients compared with controls. Spatial amplitude differences (frequ ency range 100 - 500 Hz) in the low back region were significantly (p < 0.0 1) decreased in the patients' group during sitting. Conclusion It is the first time that a decreased difference in EMG amplitud e of different parts within a certain muscle could be proven in patients wi th fibromyalgia. As far as is known from the literature this result seems t o be a unique finding in fibromyalgia patients.