Postcompetition elevation of muscle enzyme levels in professional football players.

Strenuous exercise causes a rise in circulating levels of creatine kinase (CK), and well-trained athletes liberate smaller amounts than do untrained individuals. Plasma CK, aspartate aminotransferase, and lactate dehydrogenase were measured in a group of 23 professional football players 48 hours after competition. All players were asymptomatic for myalgias or chest discomfort despite elevations of CK levels. Physicians should be aware of these elevations in muscle enzymes postexertion and interpret each in conjunction with the athlete's symptoms.