LAUSR

Following prolonged strenuous exercise there is an exercise-induced troponin (cTn) elevation in healthy individuals. The precise mechanisms and clinical consequence of this cTn elevation remain to be determined. It has recently been demonstrated that exercise intensity, exceeding a heart rate (HR) of 150 bpm, is correlated with exercise-induced cTn elevation. The present work aims to determine if there is a threshold for exercise duration with a HR exceeding 150 bpm associated with an excessive exercise-induced cTn elevation. A total of 177 healthy subjects were included in the present analysis of HR data obtained from sport watches used during a 91-km recreational mountain bike cycle race. Clinical status, cTnI, ECGs, blood pressure and demographics were obtained 24 h prior to- and at 3 h and 24 h after the race. Results are reported as median and 25th and 75th percentile. We used Tree regression to determine the association between elevated cTnI and exercise duration exceeding a HR of 150 bpm. Subjects were 82% (n=146) males, 44 (39–51) years, with a race time of 3.5 (3.1–3.9) h. Baseline cTnI was 1.9 (1.6–3.3) ng/L. There was a cTnI elevation in all study participants at 3 h, cTnI: 60.0 (36.0–99.3) ng/L, with a significant (p<0.001) reduction at 24 hours following exercise, cTnI: 10.9 (6.1–22.4) ng/L. Tree regression identified 168 min of exercise, with a HR exceeding 150 bpm, to be associated with an excessive increase in cTnI both at 3 h, and at 24 h following the race (figure). The median cTn values above and below the threshold are presented in the Table. The present analysis suggests that exceeding a specific duration of high intensity exercise may be associated with excessive cTn elevation in susceptible individuals. Type of funding source: Public grant(s) – National budget only. Main funding source(s): Western Norway Health authoritites.