Antioxidant Supplementation and Exercise-induced Cardiac Troponin Release

Abstract

It has been suggested that oxidative stress and inflammation associated with strenuous physical activity may damage the cardiomyocyte membrane, and thus stimulate the release of cardiac troponin (cTn) from the cytosol. PURPOSE: Accordingly, the purpose of the study was to investigate the influence of antioxidant supplementation upon exercise-induced cTn release. METHODS: Sixteen recreational Marathon runners volunteered to participate. Volunteers were equally, but randomly assigned to two groups and consumed 16 fl oz of a tart Montmorency cherry juice (AO) or placebo (PL) everyday for 5 days prior to, and for 24 h following the Marathon. Measures of cardiac damage, (cardiac troponin, cTn), muscle damage (creatine kinase, CK) and MVC, acute inflammation (IL-6), and total antioxidant capacity (TAC) were taken pre-supplement (TAC only), pre-race, immediately post-race, 24 h post-race. A repeated measures ANOVA was used to ascertain differences over time and between groups. RESULTS: cTn and CK were elevated post-exercise in both groups (P < 0.001), but were not different between AO and PL groups (cTn = 0.521 vs. 0.632 μg·L-1; CK = 525 vs 1007 IU·L-1, respectively). MVC decreased post-exercise in both groups and returned faster in the AO group (92% vs. 81% at 24 h, P = 0.003). There were elevations in IL-6 post-exercise that were significantly less in the AO group (40 vs. 93 pg·mL-1, P = 0.003). TAC was significantly elevated by ∼10% post-supplementation in the AO group only (P = 0.007). CONCLUSIONS: Despite there being evidence of an increase in TAC, a reduction in post-exercise inflammation and a faster return of muscle function with antioxidant supplementation, there were no differences between conditions in cTn release or indeed CK activity. These pilot data suggest that the release of cTn following strenuous physical activity might not be associated with exercise-induced oxidative stress or inflammation.