Troponin, exercise and growthexercise-induced release of cardiac troponin in healthy trained prepubertal and pubertal males

Resumen

Cardiac troponin (cTn) is a specific biomarker for heart damage, and the leading criteria for diagnosing myocardial injury. However, solid evidence proved that exercise induces as well transient elevations of cTn in the following hours. Additionally, although the physiological mechanisms underlying the exercise-induced release of cTn remain unclear, its kinetics has been determined in adults allowing its differentiation from myocardial injury, and related too with individual and exercise characteristics. Despite its characterization in adults, studies describing this phenomenon in children and adolescents are still scarce and inconclusive. Therefore, the objectives of this thesis were: (1) To describe the changes in serum cardiac troponin T (cTnT) related to exercise in healthy trained prepubertal and pubertal males; (2) To assess the effect of biological maturity on the changes in serum cTnT related to exercise in healthy trained males, and (3) To relate exercise load with the subsequent changes in serum cTnT in healthy trained prepubertal and pubertal males. Accordingly, this thesis is presented in a compendium of four publications, using different designs and methodologies: the first of them presents a systematic review and meta-analysis on the cardiac biomarker release after exercise in healthy children and adolescents; while the remaining, offer a series of three quasi-experimental, cross-sectional studies analyzing the influence of exercise load and/or maturational stage in the exercise-induced elevations of cTnT. Results of this research suggest that serum cTnT respond to exercise in healthy trained prepubertal and pubertal males with an elevation during the subsequent 3 h. Furthermore, basal cTnT, as well as the magnitude of its exercise-induced elevation are positively associated to maturational stage, with higher increases in the late-puberty. In spite of that, the rate of athletes exceeding the upper reference limits (URL) for cTn after exercise does not vary among maturational stages. Furthermore, the elevations of cTnT subsequent to exercise are associated to internal and external exercise load. Concretely, the best internal predictor for the peak cTnT concentrations was the time spent at highest cardiac intensity zone, whereas the best external predictors were the peak and average speed during exercise. The main contributions of this work were that cTnT measurements within the 3 h following exercise in healthy trained prepubertal and pubertal males might be suggestive of a rise in cTn that meets the criteria for acute myocardial injury. Additionally, the prevalence of cTn at rest and this elevation are higher in the late-puberty. Furthermore, the incidence of healthy trained prepubertal and pubertal males exceeding the URL for cTn at 3 h post-exercise is high. Contrary to prevalence, however, incidence seems not to be associated to maturational stage, suggesting that maturational differences occur in low concentrations. Finally, duration of elevated heart rate as well as peak and average speed during exercise seem to be the best predictors for the exercise-induced elevation of cTnT.