Serum creatine kinase activity

Method

Serum creatine kinase (CK) activity by clinical assay, used as a marker of exercise-induced muscle damage. Time since the damaging bout recorded on the edge.

The method is part of the endpoint identity. Studies measuring the same quantity by a different method are held as separate endpoints.

Notes

Carries a naming hazard worth stating plainly: CREATINE KINASE IS AN ENZYME, NOT CREATINE. It is reported in most sports-nutrition abstracts as a damage marker regardless of what the trial tested, which is why a naive PubMed search for "creatine" returns mostly papers about other supplements — a 43%-precision query, measured, before the ingestion term was rewritten to require creatine as a major topic. A curator reading an abstract has the same trap available. An edge from creatine to this node is a claim about muscle damage; the shared word is a coincidence of nomenclature and never evidence of a relationship.