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Cardiac troponin T and I, electrocardiographic wall motion analyses, and ejection fractions in athletes participating in the Hawaii Ironman Triathlon

https://doi.org/10.1016/S0002-9149(99)00020-XGet rights and content

Abstract

Cardiac troponin T (cTnT) and troponin I (cTnI) are highly sensitive and specific for detecting myocardial damage even in the presence of skeletal muscle injury. In this study, we assessed whether ultraendurance exercise induced cardiomyocyte injury using plasma cTnT and cTnI measurements, quantitative echocardiographic wall-motion analysis, and ejection fraction measurement in athletes who participated in the Hawaii Ironman Triathlon. Twenty-three athletes (11 men) who completed the triathlon (3.9 km swim, 180.2 km bike, and 42.2 km run) participated in this study. Blood samples were obtained 2 days before and immediately after the triathlon for the determination of cTnT (Enzymun, Roche Diagnostics) and cTnI (Dade Behring) concentrations. Quantitative echocardiographic wall motion analysis and ejection fraction were obtained on 12 of the 23 participants before and immediately after the race. No subject had detectable cTnT or cTnI or abnormal echo score before the race. Following the race, 2 subjects (9%) had marked increases in both cTnT (0.15 and 0.33 μg/L) and cTnI (2.09 and 4.44 μg/L). Four additional subjects (17%) had moderate increases in cTnT (0.04 to 0.05 μg/L) but no detectable cTnI. Race time correlated inversely with cTnT (r = −0.65, p <0.01). Mean change in the number of abnormal echo segments after the race was 6.5 in those with a marked increase in cTnT and cTnI, 2.3 in those with a moderate increase in cTnT, and 1.7 in those with no increase. Ejection fraction decreased by an average of 24% after the race (p <0.002). Thus, ultraendurance exercise may cause myocardial damage as indicated by biochemical cardiac-specific markers and echocardiography. The cellular nature of this damage and whether it is transient or permanent is unclear at present.

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Subjects

The 23 participants who completed the 1994 triathlon were exceptionally well-trained amateur athletes. Their average weekly training distances consisted of 8 km swimming, 330 km cycling, and 75 km running. Additional information regarding their training regimen has been previously reported.4 An additional group of 19 athletes, with similar training characteristics, who completed the 1995 triathlon was examined for changes in cTnT values. This study was approved by the Institutional Review Board

Results

Twenty-three subjects (11 men, age 33 ± 8 years, weight 76 ± 8 kg; 12 women, age 43 ± 14 years, weight 56 ± 5 kg) who participated in this study completed the 1994 triathlon with a mean time of 661 minutes (± 89 minutes). Mean completion time was shorter for men (586 ± 45 minutes vs 715 ± 71 minutes, p <0.0001). None of the participants had coronary or other forms of heart disease, hypertension, diabetes, or family history of premature coronary disease, and none were smokers.

The plasma

Discussion

Injury to the skeletal muscle in healthy individuals after strenuous exercise is well documented and may be the consequence of exercise-induced free radicals.9 Myoglobin and CK, present only in muscle cells, are increased following prolonged physical activity in both men and women.10, 11, 12 Both CK and myoglobin concentrations markedly increased in our subjects following the triathlon. However, despite the greater severity of this endurance exercise, these increases were comparable to those

Acknowledgements

We acknowledge Roche Diagnostics and Dade Behring for supplying the kits and instruments needed for the troponin assays, and Hewlett-Packard for echocardiographic equipment and technical assistance.

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