SERUM CARDIAC TROPONIN-T AFTER REPEATED ENDURANCE EXERCISE EVENTS

Recently Dr. Rowe made a hypothesis according to which small areas of myocardial necrosis can be caused by microvascular spasm, related to h igh catecholamine concentrations and other mechanisms, following extra ordinary unremitting endurance exercises or due to the cumulative effe ct of several endurance events. It was this last suggestion which prom pted us to investigate 25 top cyclists, taking part in the 77th Giro d 'Italia. Blood samples were obtained the day before the sta rt of the competition and once a week thereafter until the end. We measured myog lobin, lactic dehydrogenase, total creatine kinase, creatine kinase is oenzyme MB and serum cardiac troponin T (Tn-T), a highly sensitive and specific method for the detection of myocardial injury, While at meas uring time points which followed we found a significant increase in th e serum indicators of muscle damage, compared with their values at the beginning of the race, creatine kinase isoenzyme MB did not rise sign ificantly and cardiac Tn-T was found in the serum of only 5 athletes, repeatedly in some cases, but always below the cut off values consider ed as indicating myocardial ischemia. On the basis of the behaviour of creatine kinase isoenzyme MB a nd, above all, of cardiac Tn-T, we can conclude that heavy endurance exercises, repeated daily for 22 days, as was the case in our study, do not seem able to produce, in top athl etes, permanent heart damage by means of acute myocardial injury.