Resistance exercise can increase liver enzymes. Some physicians do not know this and get concerned when they see elevated ALT and AST levels in healthy men without liver disease, excessive alcohol use or medication-related liver effects.
What is already known about this subject
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.
What this study adds
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.