Can intense physical activity cause elevated liver enzymes, specifically hepatocellular damage or cholestasis, leading to abnormal liver function tests (LFTs)?

From the Guidelines

Intense exercise can indeed cause elevated liver enzymes, a condition known as exercise-induced transaminitis, which is typically temporary and benign. This occurs due to muscle damage during strenuous physical activity, such as weightlifting or endurance events, releasing enzymes like alanine aminotransferase (ALT) and aspartate aminotransferase (AST) into the bloodstream 1. Since these enzymes are present in both liver and muscle tissue, blood tests cannot distinguish their source, potentially leading to misinterpretation as liver damage. The elevation usually resolves within a few days to a week after exercise.

Key points to consider:

• The AST/ALT ratio often exceeds 1 in exercise-induced elevations, whereas in liver disease, ALT is typically higher than AST 1.
• If elevated liver enzymes are discovered after intense physical activity, it's reasonable to repeat the test after 5-7 days of rest.
• However, if elevations persist or are accompanied by symptoms like jaundice, abdominal pain, or fatigue, medical evaluation is necessary to rule out actual liver disease.
• Testing for blood levels of creatine phosphokinase (CK), aldolase, or other muscle-related enzymes can confirm the nonhepatic origin of this event 1.
• It's also important to note that patients with nonalcoholic fatty liver disease (NAFLD) may benefit from regular physical activity, with a target of 150–300 minutes of moderate-intensity or 75–150 minutes of vigorous-intensity aerobic exercise per week, as it can improve NAFLD by reducing hepatic fat content and improving insulin sensitivity 1.

From the Research

Elevated Liver Enzymes and Intense Exercise

• Intense exercise can cause elevated liver enzymes, as seen in studies where healthy individuals engaged in vigorous exercise and presented with elevated transaminase levels 2, 3.
• The liver function test measures various enzymes, including alanine aminotransferase (ALT), aspartate aminotransferase (AST), and others, which can be elevated due to extrahepatic causes such as muscular injury 2.
• Research has shown that weightlifting, a form of intense exercise, can result in significant increases in liver function tests, including AST and ALT, which can remain elevated for at least 7 days after exercise 3.

Mechanisms and Implications

• The exact mechanisms of exercise-induced liver enzyme elevation are not fully understood, but it is suspected that muscle damage-induced transaminitis may play a role 2.
• Studies have highlighted the importance of considering intense exercise as a potential cause of asymptomatic elevations of liver function tests in daily clinical practice 3.
• It is essential to impose restrictions on heavy muscular exercise prior to and during clinical studies to avoid misinterpretation of liver function test results 3.

Clinical Relevance

• The elevation of liver enzymes due to intense exercise is usually transient and resolves on its own after discontinuation of the exercise 2.
• Clinicians should be aware of the potential for intense exercise to cause elevated liver enzymes and consider this in the differential diagnosis of patients with raised transaminase levels 2, 3.