Arterial stiffness and subendocardial viability ratio: temporal responses to ultra-endurance exercise

Ultra-endurance exercise causes significant cardiovascular stress, yet the vascular responses during recovery remain incompletely understood. This study examined the short- (12–18 h) and longer-term (7 and 28 days) effects of a long-distance triathlon on arterial stiffness and subendocardial viability ratio (SEVR) in novice triathletes. Eleven participants (two females, nine males), novice to long-distance exercise events, completed cardiovascular assessments at baseline (pre-race), 12–18 h post-race, and 7- and 28-days post-race. Measures included carotid-femoral pulse wave velocity (PWV), augmentation index (Aix), and SEVR, obtained via applanation tonometry. PWV remained unchanged at all post-exercise time points ( P = 0.310). Aix showed significant reduction at 7 days post-event ( P = 0.024), though this effect was abolished after normalizing values to a heart rate of 75 beats per minute (Aix75, P = 0.162). SEVR decreased significantly 12–18 h post-race ( P < 0.001), indicating a transient imbalance between myocardial supply and demand, likely driven by elevated heart rates and reduced diastolic perfusion time. SEVR returned to baseline by 7 days post-event. These findings suggest that while no sustained changes in arterial stiffness were observed, hemodynamic conditions during recovery may signify altered myocardial supply–demand balance in novice athletes. Further research is needed to explore these mechanisms, with enhanced temporal resolution, to better understand the cardiovascular implications for novice endurance athletes.