title: Patients with primary biliary cirrhosis do not show post-exercise depression of cortical excitability.
abstract: OBJECTIVE
  Primary biliary cirrhosis (PBC), a female-predominant autoimmune liver disease, is commonly associated with fatigue, a sensation of weariness from physical activity. In healthy subjects, motor evoked potentials (MEPs) elicited by transcranial magnetic stimulation (TMS) increase in amplitude during fatiguing exercise and decrease after the exercise due to post-contraction cortical excitability depression. TMS was utilized herein to investigate if unique cortical excitability changes discriminate women with PBC from healthy controls.
  
  
  METHODS
  Twenty-two women (11 with PBC and 11 healthy controls) performed a voluntary submaximal tonic contraction of finger flexor muscles until exhaustion; MEPs were recorded before and during exercise as well as 10min after exercise discontinuation. All subjects completed questionnaires for quality of life and fatigue evaluation.
  
  
  RESULTS
  During exercise an increase in MEPs amplitude was observed in all subjects, with no sign of altered peripheral fatigability. Following exercise women with PBC associated with high fatigability showed a significant lack of reduction of MEP size compared to the healthy controls.
  
  
  CONCLUSIONS
  Women with PBC do not manifest post-exercise depression of cortical excitability.
  
  
  CONCLUSIONS
  We suggest that an impairment of neural mechanisms underlying physiological central fatigue could occur in PBC, possibly leading to the pathological fatigability lamented by some patients.
authors.affiliation: Department of Human Physiology, Università degli Studi, Milan, Italy.
authors.forename: Gabriella
authors.initials: G
authors.lastname: Cerri
authors.forename: Claudio A
authors.initials: CA
authors.lastname: Cocchi
authors.forename: Marcella
authors.initials: M
authors.lastname: Montagna
authors.forename: Massimo
authors.initials: M
authors.lastname: Zuin
authors.forename: Mauro
authors.initials: M
authors.lastname: Podda
authors.forename: Paolo
authors.initials: P
authors.lastname: Cavallari
authors.forename: Carlo
authors.initials: C
authors.lastname: Selmi
mesh_terms: D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D002540:Cerebral Cortex / Q000503:physiopathology*; D004558:Electric Stimulation; D004576:Electromyography; D019054:Evoked Potentials, Motor / Q000502:physiology*; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D008105:Liver Cirrhosis, Biliary / Q000503:physiopathology*; D008875:Middle Aged; D009119:Muscle Contraction / Q000502:physiology; D018763:Muscle Fatigue / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology; D010807:Physical Endurance / Q000502:physiology; D005082:Physical Exertion / Q000502:physiology*; D011788:Quality of Life; D012815:Signal Processing, Computer-Assisted; D018709:Statistics, Nonparametric; D011795:Surveys and Questionnaires; D050781:Transcranial Magnetic Stimulation