Ultra-endurance (>180 min) sporting events are known to provoke transient functional and biochemical cardiac perturbations that may persist for 24-48 h post exercise. However, the time-course recovery of functional and biochemical cardiac perturbations induced by shorter duration exercise that is typical of day-to-day endurance training is not clear.

PURPOSE: This study examined indices of ventricular function at baseline and during recovery from a 90-min high-intensity cycling bout that is typical of day-to-day training sessions undertaken by athletes.

METHODS: High-sensitivity cardiac troponin I (hs-cTnI) and echocardiograph-derived left (LV) and right (RV) ventricular global longitudinal strain (GLS) were assessed in 8 recreational athletes (age: 27 ± 3 yr; VO2peak: 3.8 ± 0.7 L/min) at baseline and during recovery (1-, 3-, 6- & 22-h) from exercise.

RESULTS: Average heart rate and VO2 during the 90-min cycling bout were 154 ± 5 beats/min and 3.1 ± 0.4 L•min-1, respectively. Serum hs-cTnI increased significantly after exercise (Pre: 5.9 ± 3.3 v Immediately Post: 10.9 ± 2.9 ng/L, p < 0.05) and remained elevated at 1- (16.7 ± 5.9), 3- (23.8 ± 7.8) and 6-h (25.4 ± 9.7 ng/L) post, returning to baseline at 22-h post (8.2 ± 3.3 ng/L). LV and RV GLS both decreased significantly (p < 0.05) after exercise and remained lower at 1-, 3- & 6-h post (LV: Pre: -19.8 ± 0.7; 1h: -17.7 ± 0.9; 3h: -18.8 ± 0.7; 6h: -17.8 ± 0.9%; RV: Pre: -26.8 ± 0.9; 1h: -25.8 ± 1.0; 3h: -25.2 ± 1.0; 6h: -23.7 ± 1.1%). Although strain tended to remain decreased at 22h post (LV: -19.2 ± 0.6%; RV: -25.6 ± 1.2%), this was not significantly different from baseline (p > 0.05).

CONCLUSIONS: This study demonstrates that exercise-induced functional and biochemical cardiac perturbations transpire during exercise that is typical of day-to-day training undertaken by endurance athletes and persists for > 6 hours into recovery. It remains unclear if these changes reflect a positive, negative or neutral physiological response with respect to long-term cardiac adaptations.