BACKGROUND: While the promotion of health-related fitness is thereby widespread, 
less focus is currently being given on the biological influence that physical 
activity might exert on results of laboratory testing. As such, this study was 
undertaken to assess the kinetics of liver injury markers following physical 
exercise.
DESIGN AND METHODS: Total and direct bilirubin as well as the activity of 
biochemical markers of liver injury including aspartate aminotransferase (AST), 
alanine aminotransferase (ALT), alkaline phosphatase (ALP), lactate 
dehydrogenase (LDH), gamma-glutamyl transpeptidase (GGT) and creatine kinase 
(CK), were measured before and after a half-marathon.
RESULTS: Significant increases occurred for GGT, AST, LDH, CK, total and direct 
bilirubin immediately after the run. AST, LDH, CK, total and direct bilirubin 
were still increased 24h thereafter, whereas GGT decreased after 6h. None of the 
athletes exceed the upper reference limit for ALT, ALP and GGT, whereas 
significant variations were instead observed for LDH, AST, CK, total and direct 
bilirubin.
CONCLUSIONS: Taken together, the results of our prospective investigation 
clearly attest that an acute bulk of aerobic physical exercise, such as a 
half-marathon, might produce significant changes in the activity of traditional 
biomarkers of liver injury, which should be carefully considered when 
investigating physically active individuals undergoing laboratory testing.