This meta-data exploration aimed to determine the impact of exertional-heat stress (EHS) on gastrointestinal status of masters age and young adult endurance athletes. Sixteen MASTERS (mean: 44y) and twenty-one YOUNG (26y) recreational endurance athletes completed 2 h of running at 60% ˙V O2max in 35˚C ambient conditions. Blood samples were collected pre-, immediately and 1 h post-EHS, and analyzed for markers of exercise-induced gastrointestinal syndrome (EIGS). Thermo-physiological measures and gastrointestinal symptoms (GIS) were recorded every 10-20 min during EHS. Peak Δ pre- to post-EHS did not substantially differ (p>0.05) between MASTERS and YOUNG for intestinal epithelial injury [I-FABP: 1652pg/ml vs. 1524pg/ml, respectively], bacterial endotoxic translocation [sCD14: -0.09µg/mL vs. 0.84µg/mL, respectively], lipopolysaccharide-binding protein [LBP: 0.26µg/mL vs. 1.76µg/mL, respectively], and systemic inflammatory response profile (SIR-Profile: 92.0arb.unit vs. 154arb.unit, respectively). A significantly higher peak Δ pre- to post-EHS in endogenous endotoxin anti-body IgM (p=0.042), and pro-inflammatory cytokine IL-1β (p=0.038), was observed in YOUNG compared to MASTERS. No difference was observed between incidence (81% and 80%, respectively) and severity (summative accumulation: 21 and 30, respectively) of reported GIS during EHS between MASTERS and YOUNG. Pathophysiology of EIGS in response to EHS does not substantially differ with age progression, since masters and younger adult endurance athletes responded comparably.
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