Does submaximal physical exercise increase serum CPK levels enough to impair the diagnosis of acute myocardial infarction in untrained individuals?
Submaximal physical exercise causes minimal CPK elevation, indicating that recent heavy physical work rarely confounds the CPK-based diagnosis of acute myocardial infarction.
Serial estimations of total serum creatine phosphokinase (CPK) have been performed before and during 18-49 hours after submaximal physical exercise in 17 untrained individuals, mean age 50 years. The maximal CPK increase after exercise was 32 mU/ml (73%). The serum CPK did not exceed the upper normal limit (130 mU/ml) except in one individual (150 mU/ml). The maximal CPK increase in patients with acute myocardial infarction (AMI) varied between 101 mU/ml (133%) and 2 260mU/ml(3 790%), mean 900 mU/ml (1 184%). As the maximal CPK elevation in AMI occurs within the same period, it seems that heavy physical work of short duration just before the onset of symptoms will very seldom impair the diagnosis of AMI with the CPK technique used.
Forssell et al. (Sun,) studied this question.