title: Muscular exercise can cause highly pathological liver function tests in healthy men.
abstract: BACKGROUND
  The occurrence of idiosyncratic drug hepatotoxicity is a major problem in all phases of clinical drug development and the leading cause of postmarketing warnings and withdrawals. Physical exercise can result in transient elevations of liver function tests. There is no consensus in the literature on which forms of exercise may cause changes in liver function tests and to what extent.
  
  
  CONCLUSIONS
  Weightlifting results in profound increases in liver function tests in healthy men used to moderate physical activity, not including weightlifting. Liver function tests are significantly increased for at least 7 days after weightlifting. It is important to impose relevant restrictions on heavy muscular exercise prior to and during clinical studies.
  
  
  OBJECTIVE
  To investigate the effect of intensive muscular exercise (weightlifting) on clinical chemistry parameters reflecting liver function in healthy men.
  
  
  METHODS
  Fifteen healthy men, used to moderate physical activity not including weightlifting, performed an 1 h long weightlifting programme. Blood was sampled for clinical chemistry parameters [aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LD), gamma-glutamyl transferase (gamma GT), alkaline phosphatase (ALP), bilirubin, creatine kinase (CK) and myoglobin] at repeated intervals during 7 days postexercise and at a follow-up examination 10-12 days postexercise.
  
  
  RESULTS
  Five out of eight studied clinical chemistry parameters (AST, ALT, LD, CK and myoglobin) increased significantly after exercise (P < 0.01) and remained increased for at least 7 days postexercise. Bilirubin, gamma GT and ALP remained within the normal range.
  
  
  CONCLUSIONS
  The liver function parameters, AST and ALT, were significantly increased for at least 7 days after the exercise. In addition, LD and, in particular, CK and myoglobin showed highly elevated levels. These findings highlight the importance of imposing restrictions on weightlifting prior to and during clinical studies. Intensive muscular exercise, e.g. weightlifting, should also be considered as a cause of asymptomatic elevations of liver function tests in daily clinical practice.
authors.affiliation: AstraZeneca R&D Lund, Lund, Sweden.
authors.forename: Jonas
authors.initials: J
authors.lastname: Pettersson
authors.forename: Ulf
authors.initials: U
authors.lastname: Hindorf
authors.forename: Paula
authors.initials: P
authors.lastname: Persson
authors.forename: Thomas
authors.initials: T
authors.lastname: Bengtsson
authors.forename: Ulf
authors.initials: U
authors.lastname: Malmqvist
authors.forename: Viktoria
authors.initials: V
authors.lastname: Werkström
authors.forename: Mats
authors.initials: M
authors.lastname: Ekelund
mesh_terms: D000293:Adolescent; D000328:Adult; D000410:Alanine Transaminase / Q000097:blood; D001219:Aspartate Aminotransferases / Q000097:blood; D004796:Clinical Enzyme Tests / Q000639:trends*; D015444:Exercise / Q000502:physiology; D006801:Humans; D008099:Liver / Q000378:metabolism* / Q000473:pathology*; D008111:Liver Function Tests / Q000639:trends; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000378:metabolism*; D013997:Time Factors; D014891:Weight Lifting / Q000502:physiology*; D005723:gamma-Glutamyltransferase / Q000097:blood
chemical_list: D005723:gamma-Glutamyltransferase; D001219:Aspartate Aminotransferases; D000410:Alanine Transaminase