Patients should abstain from exercise before CPK and troponin tests because exercise can cause elevated levels of these markers, potentially leading to false positive results for myocardial damage. CPK and troponin are substances released by muscles during strenuous activity or muscle injury, which is why resting before the test is recommended.
Patients should refrain from exercise before the test for creatinine phosphokinase (CPK) and troponin because exercise may falsely elevate CPK and troponin levels. CPK is an enzyme that is present in the cardiac muscle, skeletal muscle, and brain, and is involved in the conversion of creatine to creatine phosphate, which supplies energy during muscle contraction. Troponin is a regulatory protein for muscle contraction that can be released into the bloodstream when cardiac muscle cells are damaged, as in the case of a myocardial infarction (MI).
Exercise prior to testing can increase the levels of CPK and troponin, as vigorous physical activity can cause some muscle injury leading to the release of these enzymes and proteins. This can result in a false positive result, suggesting myocardial damage when there may be none. Elevated levels of CPK-MB, an isoenzyme of CPK, and cardiac troponin are common blood test indicators of an MI, confirming the condition along with an ECG and potentially an echocardiography or cardiac magnetic resonance imaging.