A comparison of modelled serum cTnT and cTnI kinetics after 60 min swimming.

Post-exercise elevations of cardiac troponin T (cTnT) and I (cTnI) are often used in isolation but interpreted interchangeably. Research suggests, however, that post-exercise cTn kinetic might differ with each isoform. In this cross-sectional observational study, we collected blood samples before, immediately after (5 minutes), and at 1-, 3-, 6-, 12-, and 24-hour post-exercise in a mixed cohort of 56 participants after a distance-trial of 60 min continuous swimming (age range from 14 to 22, 57.1% female). Cardiac troponin kinetics were modelled using Bayesian mixed-effects models to estimate time to peak (TTP) and peak concentration (PC) for each isoform, while controlling for participants sex, tanner stage and average relative heart rate during the test. Exercise induced an elevation of cTnT and cTnI in 93% and 75% of the participants, respectively. Cardiac troponin T peaked earlier, at 2.9 h (CI: 2.6 - 3.2 h) post-exercise, whereas cTnI peaked later, at 4.5 h (CI: 4.2 - 4.9 h). Peak concentrations for cTnT and cTnI were 2.5 ng/L, CI: 0 - 11.2 ng/L and 2.16 ng/L, CI: 0 - 22.7 ng/L, respectively. Additionally, we did not observe a systematic effect of sex and maturational status mediating cTn responses.

The kinetics of cardiac troponin T release during and after 1- and 6-h maximal cycling trials.

OBJECTIVES: In this study, the effects of short-duration high-intensity exercise and long-duration exercise on high-sensitivity cardiac troponin T (hs-cTnT) levels were compared. METHODS: Twelve male amateur cyclists performed 1- and 6-h cycling trials. In both exercise trials, hs-cTnT was assessed at rest, immediately postexercise and at 1, 3, 6, 12, and 24 h postexercise. Additionally, hs-cTnT levels were assessed every hour during the 6-h trial. RESULTS: Exercise resulted in an increase in hs-cTnT levels in all subjects. Circulating hs-cTnT levels increased in both exercise trials (p < 0.001), with higher peak values occurring after the 1-h trial compared with those of the 6-h trial (p = 0.023). The upper reference limit (URL) exceeded 83 % of the participants in the 1-h trial and 42 % of the participants in the 6-h trial. There was substantial individual variability in peak hs-cTnT in both trials. Values of hs-cTnT were greater after exercise than during exercise for the 6-h trial. For both exercise trials, the maximum postexercise hs-cTnT values correlated with the %HRMAX (r = 0.906 for the 1-h trial, r = 0.735 for the 6-h trial). For the 1-h trial, the maximum postexercise hs-cTnT values were observed at 3 h in all subjects. No significant difference in the hs-cTnT values was observed for the 6-h trial during the first 12 h postexercise. CONCLUSIONS: Our results demonstrated greater hs-cTnT levels in young male participants after a 1-h cycling trial than after a 6-h cycling trial, despite a substantially greater energy expenditure and total external work completed in the 6-h trial. Postexercise hs-cTnT values are associated with relative exercise intensity.