Objectives To determine the influence of maturational status on the release of cardiac troponin T (cTnT) induced by a bout of 30 min, high-intensity, continuous exercise. Design Quasi-experimental, cross-sectional study. Methods Seventy male, young, well trained swimmers (age range 7–18 years, training experience 1–11 years) were classified by maturational stages: Tanner stage I (n = 14), II (n = 15), III (n = 15), IV (n = 13), and V (n = 13). Participants underwent a distance-trial of 30 min continuous swimming, and cTnT was measured before, immediately after and 3 h after exercise. Changes in cTnT over time were compared among groups, and associated with exercise load. Results Basal cTnT was higher in Tanner-V (3.8–8.1 ng/L) compared with I (1.5–5.5ng/L, p < 0.001), II (1.5–4.5ng/L, p < 0.001) and III (1.5–6.8ng/L, p = 0.003), and in IV (1.5–6.3 ng/L) compared with II (p = 0.036). Maximal elevations of cTnT from baseline were notable (p < 0.001) and comparable among maturational stages (p = 0.078). The upper reference limit for myocardial injury was exceeded in 35.7% of the participants, without differences among groups (p = 0.18). Baseline cTnT correlated with participant characteristics, and maximal cTnT elevations from baseline with exercise internal load (%HRpeak, rs = 0.34, p =  0.003; %HRmean, rs = 0.28, p = 0.02). Conclusions Maturational status influences positively absolute pre- and post-exercise cTnT but not its elevation after a bout of 30 min, high-intensity, continuous exercise.