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The cardiospecificity of the third-generation cTnT assay after exercise-induced muscle damage
Robert Shave1, Ellen Dawson, Gregory Whyte
1British Olympic Medical Centre, Northwick Park, Harrow, London, UK. robshave@yahoo.com
Insights
Maximal exercise and downhill running did not impair cardiac function in trained athletes. Elevated muscle damage markers (CK and CKMB) were noncardiac, confirming the specificity of cardiac troponin assays (cTnT, cTnI) for detecting myocardial injury.
Area of Science:
- Exercise Physiology
- Cardiology
- Biochemistry
Background:
- Assessing cardiac function after strenuous exercise is crucial, especially in highly trained individuals.
- Exercise can induce skeletal muscle damage, potentially confounding cardiac biomarker interpretation.
- Newer cardiac troponin assays (cTnT, cTnI) offer improved specificity.
Purpose of the Study:
- To evaluate the cardiospecificity of cTnI and third-generation cTnT assays.
- To determine the impact of exercise-induced muscle damage on cardiac function.
- To assess cardiac function after a maximal-ramping treadmill test and downhill running.
Main Methods:
- Eight highly trained male triathletes underwent maximal treadmill tests and 30-minute downhill runs.
- Cardiac function was assessed via ECG and echocardiography (rest, immediate post-exercise, 48h post-exercise).
- Blood analysis included creatine kinase (CK, CKMB), cTnT, and cTnI to detect myocyte damage.
Main Results:
- Echocardiography revealed normal left ventricular function throughout the study.
- Total CK and CKMB levels significantly increased 48 hours post-downhill run.
- Cardiac troponins (cTnT, cTnI) remained undetectable, indicating no myocardial damage.
Conclusions:
- Neither exercise protocol induced cardiac dysfunction or myocardial damage in trained athletes.
- Elevated CK and CKMB post-downhill running were of noncardiac origin.
- cTnI and third-generation cTnT assays reliably detect cardiac damage, even with elevated skeletal muscle markers.
Purpose:
The purpose of the present study was to examine the cardiospecificity of cTnI and the new third-generation cTnT assay, in the presence of exercise-induced muscle damage in highly trained individuals, and to examine the impact of a maximal-ramping treadmill test on cardiac function.
Methods:
Eight highly trained male triathletes (mean +/- SD; age: 29 +/- 9 yr; height: 1.79 +/- 0.10 m; body mass: 77 +/- 10 kg; .VO(2max): 67.4 +/- 6.3 mL.kg(-1).min(-1)) completed two bouts of exercise. On the first occasion, subjects completed a maximal-ramping treadmill test. On a separate occasion, the subjects completed 30 min of downhill running (15% gradient) at a speed equivalent to 70% of maximal running velocity attained during the maximal-ramping treadmill test. All subjects were assessed using ECG, echocardiography, and blood analysis. Measurements were taken at rest, immediately after, and 48 h postexercise for each bout of exercise. Echocardiographic analysis was used to determine left ventricular systolic and diastolic function. Blood samples were analyzed for markers of myocyte damage.
Results:
Echocardiographic results indicated normal left ventricular function before and after both exercise bouts. Total CK and CKMB were significantly elevated 48 h after the downhill run. cTnT and cTnI were not elevated at any stage of the study.
Conclusions:
Neither the maximal-ramping treadmill test nor the 30-min downhill run produced cardiac dysfunction or myocardial damage in young, healthy trained subjects. The elevated total CK and CKMB within the downhill study are noncardiac in origin as demonstrated by the lack of cTnT and cTnI. The cTnI and new third-generation cTnT assays may be used to detect cardiac damage in the presence of elevated total CK and CKMB associated with exercise-induced skeletal muscle damage.