title: Muscle fatigue in women with primary biliary cirrhosis: Spectral analysis of surface electromyography.
abstract: OBJECTIVE
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Clinical Pathophysiology, Gastroenterology Unit, University of Florence, Viale Morgagni 85 50134, Firenze, Italy.
authors.forename: Maria Rosa
authors.initials: MR
authors.lastname: Biagini
authors.forename: Alessandro
authors.initials: A
authors.lastname: Tozzi
authors.forename: Antonello
authors.initials: A
authors.lastname: Grippo
authors.forename: Andrea
authors.initials: A
authors.lastname: Galli
authors.forename: Stefano
authors.initials: S
authors.lastname: Milani
authors.forename: Aldo
authors.initials: A
authors.lastname: Amantini
mesh_terms: D000328:Adult; D000368:Aged; D015992:Body Mass Index; D004576:Electromyography / Q000379:methods*; D005260:Female; D006801:Humans; D007537:Isometric Contraction; D008105:Liver Cirrhosis, Biliary / Q000150:complications* / Q000473:pathology*; D008875:Middle Aged; D018763:Muscle Fatigue; D009132:Muscles / Q000473:pathology*