We compared the effects of exercise on serum levels of creatin kinase (CK) in athletes with persistent hyperCKemia at rest (CK group) and in healthy athletes (control group). Prospective controlled study. Eighteen male Caucasian athletes with high serum CK levels at rest (CK between 80 and 150 U/L) and 25 male Caucasian athletes with normal serum CK levels at rest (CK between 10 and 80 U/L).Blood samples were collected at rest, 30 minutes, 6 hours, 24 hours, 48 hours and 72 hours after a progressive cycloergometer test to exhaustion. The levels of serum CK and its isoenzymes were measured. In the control group, serum CK values at rest were normal (48.18 ± 14.14 U/L). After exercise, they increased slightly, though they always remained80 U/L, decreasing to the rest level after 48 hours. The CK group had serum CK levels at rest higher than normal (116.56 ± 33.30 U/L). Serum CK levels were still outwith the normal range after 48 hours (130.11 ± 46.95 U/L) and 72 hours (116.55 ± 24.84 U/L). Serum CK levels were significantly different in both groups both before and after progressive cycloergometer test to exhaustion. In athletes with high serum CK levels at rest, serum CK levels remained elevated and had a different kinetics after exercise when compared with healthy athletes.
