Exercise-induced changes in creatine kinase: a systematic review

Creatine kinase (CK) is a key enzyme in cellular energy metabolism, playing a role in the regeneration of adenosine triphosphate through the phosphocreatine system, particularly in tissues with high energy demands such as skeletal muscle. Under normal conditions, CK is present within muscle cells, so its blood levels are relatively low. However, strenuous or unusual physical exercise especially with eccentric contractions can cause mechanical and metabolic stress that disrupts muscle fiber integrity and increases cell membrane permeability. Microdamage to the sarcolemma, accompanied by oxidative stress, inflammatory responses, and disruption of intracellular calcium homeostasis, are thought to cause the release of CK from muscle cells into the bloodstream. Although CK is widely used as a biomarker of exercise-induced muscle damage, its increased levels do not always correlate directly with the degree of muscle damage or functional impairment, so the exact mechanism of post-exercise CK release remains incompletely understood. The aim of this study was to determine the effect of physical exercise on increasing CK levels. We reviewed several literature databases, including Scopus, Pubmed, Web of Science, and Science Direct, for our systematic review investigation. The search was conducted for articles published between 2015-2025 that discussed physical exercise and CK. Using the Scopus, Web of Science, Pubmed, and Science Direct databases, 1,450 published publications were identified. For this systematic review, nine papers that met the inclusion criteria were selected and reviewed. This study evaluated the standard operating procedure using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). Based on 9 reviewed papers it has been proven that physical exercise has been proven to increase CK levels significantly. Exercise-induced CK elevations serve as a valuable, albeit nonspecific, indicator of muscle damage. Understanding the variability in CK responses is critical to designing training and recovery programs for athletes in order to achieve optimal physical performance.