Muscle fatigue in women with primary biliary cirrhosis: Spectral analysis of surface electromyography.
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.
Biagini
Maria Rosa
MR
Department of Clinical Pathophysiology, Gastroenterology Unit, University of Florence, Viale Morgagni 85 50134, Firenze, Italy.
Tozzi
Alessandro
A
Grippo
Antonello
A
Galli
Andrea
A
Milani
Stefano
S
Amantini
Aldo
A
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*