What is AST?
AST can increase with liver stress, but also after intense exercise, muscle soreness, or muscle injury. That is why AST is usually evaluated together with ALT and GGT, and in the context of training load and symptoms. Trends help distinguish a one-off spike from a persistent pattern.
Why is AST relevant?
AST is an enzyme present in liver, heart, and especially in muscle tissue — which makes it respond to more than just liver load. With intensive physical effort, muscle damage, or overload, AST can rise substantially even with a healthy liver. For athletes, that is a marker worth getting to know: it moves with training load.
How to read AST in context
Always read AST alongside ALT, GGT, and bilirubin. When AST is much higher than ALT, muscle activity or intensive training often plays a role; when both are elevated together along with GGT, the weight shifts more toward the liver. For a reliable measurement, wait a few days after heavy training; trends across several measurements give the fairest picture.