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World J Gastroenterol. Aug 28, 2006; 12(32): 5186-5190
Published online Aug 28, 2006. doi: 10.3748/wjg.v12.i32.5186
Muscle fatigue in women with primary biliary cirrhosis: Spectral analysis of surface electromyography
Maria Rosa Biagini, Alessandro Tozzi, Antonello Grippo, Andrea Galli, Stefano Milani, Aldo Amantini
Maria Rosa Biagini, Alessandro Tozzi, Andrea Galli, Stefano Milani, Department of Clinical Pathophysiology, Gastroenterology Unit, University of Florence, AOU Careggi, Firenze, Italy
Antonello Grippo, Aldo Amantini, Department of Neurological Science, Neurophysiological Unit, University of Florence, AOU Careggi, Firenze, Italy
Author contributions: All authors contributed equally to the work.
Correspondence to: Tozzi Alessandro, MD, Department of Clinical Pathophysiology, Gastroenterology Unit, University of Florence, Viale Morgagni 85 50134, Firenze, Italy. aletozzi@yahoo.it
Telephone: +39-55-4271411 Fax: +39-55-4222409
Received: December 18, 2005
Revised: March 10, 2006
Accepted: March 17, 2006
Published online: August 28, 2006
Abstract

AIM: To evaluate the myoelectric manifestations of peripheral fatigability in patients with primary biliary cirrhosis in comparison to healthy subjects.

METHODS: Sixteen women with primary biliary cirrhosis without comorbidity and 13 healthy women matched for age and body mass index (BMI) completed the self-reported questionnaire fatigue impact scale. All subjects underwent surface electromyography assessment of peripheral fatigability. Anterior tibial muscle isometric voluntary contraction was executed for 20 s at 80% of maximal voluntary isometric contraction. During the exercise electromyographic signal series were recorded and root mean square (expression of central drive) as well as mean and median of electromyographic signal frequency spectrum (estimates of muscle fatigability) were computed. Each subject executed the trial two times. EMG parameters were normalized, then linear regression was applied and slopes were calculated.

RESULTS: Seven patients were fatigued (median fatigue impact scale score: 38, range: 26-66) and 9 were not fatigued (median fatigue impact scale score: 7, range: 0-17). The maximal voluntary isometric contraction was similar in patients (82, 54-115 N) and controls (87, 74-101 N), and in patients with high (81, 54-115 N) and low fatigue impact scale scores (86, 65-106 N). Root mean square as well as mean and median of frequency spectrum slopes were compared with the Mann-Whitney U test, and no significant difference was found between fatigued and non-fatigued patients and controls.

CONCLUSION: No instrumental evidence of peripheral fatigability can be found in women with primary biliary cirrhosis but no comorbidity, suggesting that fatigue in such patients may be of central origin.

Keywords: Primary biliary cirrhosis; Cholestasis; Surface electromyography; Peripheral fatigue; Muscle fatigue; Fatigability; Root mean square; Mean frequency; Median frequency; Fatigue impact scale