ABSTRACT
BACKGROUND: Aging decreases ischemic tolerance, while exercise prevents myocardial ischemia reperfusion (IR) injury. The cardioprotective role of high intensity interval training (HIIT), however, is unknown. METHODS: Accordingly, we investigated 8 weeks (5 days/week, 40 min/day) of HIIT treadmill exercise (60%/90% of VO2 peak) on IR injury in young (2-month) and senescent (20-month) Wistar rat myocardia (N = 10/group). Surgical IR (30 min/120 min) was performed via reversible left anterior descending artery ligation and ECG was analyzed to determine ventricular ectopy during IR period. RESULTS: Infarction size and oxidative stress were measured in hearts post-mortem. Glutathione peroxidase activity and Myeloperoxidase levels were mitigated with age, but elevated post IR. HIIT potentiated antioxidant defenses in young and old hearts, and infarction size was lower in young HIIT trained. Metrics of reactive oxygen species were not lower after IR, and were not affected by HIIT in young or old rats. Ventricular ectopy score in senescent rats was insignificantly more than young rats and HIIT significantly decreased ventricular ectopy score in young and senescent rats. CONCLUSIONS: Findings indicate that IR tolerance is mitigated in senescent hearts, while HIIT ameliorated infarction by increasing antioxidant enzymes activity in young and senescent hearts.
