RESUMO
BACKGROUND: The reasons for the appearance of cardiacspecific troponin (cTnT) after strenuous exercise are unclear. The aim of the present study was to evaluate the cardiospecificity of the 3(rd) generation cardiac cTnT assay during and after an ultra-endurance race of 216 km at extreme environmental conditions in Death Valley. STUDY DESIGN AND METHODS: We measured serially cTnT, creatine kinase (CK), activity and mass of the isoenzyme MB of CK (CK-MB(act) and CK-MB(mass)), and myoglobin in 10 well-trained athletes before, repeatedly during and after the race. RESULTS: Six of 10 participants finished the race within a preset time of 60 hours. Postrace values of biochemical markers CK, CK-MB(act), CKMB(mass), and myoglobin were significantly increased compared to baseline (p<0.05). CK-MB(act) increased from (median (25(th)/ 75(th)percentile) 12 (10/13) U/L to 72 (32/110) U/L, CK-MB(mass) from 3.9 (2.9/5.6) U/L to 65 (18/80) U/L and CK increased from median 136 (98/ 228) U/L to 3,570 (985/6,884) U/L respectively. Pre-race myoglobin was 27 (22/31) microg/l compared to 530 (178/657) microg/l after the run. One runner developed significant exercise-induced rhabdomyolysis with spontaneous recovery. cTnT values remained below the 99(th) percentile reference limit in all athletes including the runner who developed significant rhabdomyolysis (peak CK 27,951 U/L). CONCLUSIONS: Strenuous endurance exercise, even under extreme environmental conditions, does not result in structural myocardial damage in well-trained ultra-endurance athletes. We found no crossreactivity between cTnT and CK, neither in exercise-induced skeletal muscle trauma nor after rhabdomyolysis underscoring the excellent analytical performance of 3(rd) generation cTnT assay.
