Exercise Physiological Insights into Exercise-Induced Muscle Cramping: Blood Lactate and Creatine Kinase as Biomarkers in College Students

William Yu, College of Saint Benedict and Saint John's University

Abstract

Creatine kinase (CK) is an enzyme that's found in the skeletal muscle, heart muscle and brain. When any of these tissues are damaged, they leak creatine kinase into your bloodstream. Elevated CK levels may indicate muscle injuries, cramping, or disease1. There are different types of CK, which are also known as isozymes for the cytoplasm, CK-MM, CK-MB, and CK-BB. CK-MM focuses on musculoskeletal, CK-MB focuses on heart muscles, and CK-BB focuses on the brain tissue. There are also two isozymes in the mitochondria15. Cramping is common problem amongst runners and can be described as “painful, spasmodic contraction of the skeletal muscle that occurs during or immediately after muscular exercise”4. CK is frequently described as the best indirect marker of damage to muscle tissue, especially after resistance exercise or other exercises that require predominantly eccentric action3. CK has also been associated with muscle cramps2. We want to see the correlation between cramping and CK. CK levels transiently rise after exercise or heavy manual labor. Serum CK levels may increase to as much as 30 times the upper limit of normal within 24 hours of strenuous physical activity, then slowly decline over the next 7 days. The degree of CK elevation depends on the type and duration of exercise, with greater elevation in those who are untrained5. As a runner myself, I am interested in seeing the effects of cramping on the body and hopefully this will help take care of my body for running in the future. If a person exercises and cramps up, then their CK-MM levels should increase because due to the serum levels rising 24 hours post-exercise according to literature.