12-Week Exercise Training, Independent of the Type of Exercise, Attenuates Endothelial Ischaemia-Reperfusion Injury in Heart Failure Patients

Abstract

<b>Introduction:</b> Reperfusion is required to salvage ischaemic tissue, but also causes further damage (i.e., ischaemia/reperfusion-injury). Heart failure patients reveal exaggerated ischaemia/reperfusion-injury, whilst traditional ischaemic preconditioning cannot prevent ischaemia/reperfusion-injury. Exercise training may be a more powerful preconditioning stimulus, especially high-intensity interval training given the similarities with ischaemic preconditioning. Therefore, we examined the impact of 12-week continuous training vs. high-intensity interval training on brachial artery endothelial ischaemia/reperfusion-injury in heart failure patients New York Heart Association-class II-III. <b>Methods:</b> Twenty heart failure patients (male:female 19:1, 64 ± 8 years, ejection fraction 38 ± 6%) were allocated to 12-weeks of high-intensity interval training (10^∗1-min 90% maximal workload - 2.5-min 30% maximal workload) or continuous training (30-min 60-75% maximal workload). Before and after the intervention, we measured brachial artery endothelial function with flow-mediated dilation (FMD) before and after ischaemia/reperfusion (5-min ischemic exercise, 15-min reperfusion). <b>Results:</b> Ischaemia/reperfusion caused a significant decline in FMD (continuous training (<i>n</i> = 10): 5.2 ± 2.5 to 3.4 ± 1.6%, high-intensity interval training (<i>n</i> = 10): 5.3 ± 2.6 to 3.5 ± 1.6%, <i>P</i> = 0.01), which was not different between groups (<i>P ></i> 0.05). Training improved maximal workload and fitness (<i>P</i> < 0.05), with no differences between groups (<i>P ></i> 0.05). Exercise training did not alter FMD (<i>P ></i> 0.05), whilst ischaemia/reperfusion did not impair FMD after exercise training (continuous training: 4.8 ± 3.0 to 4.2 ± 2.3%, high-intensity interval training: 4.7 ± 2.5 to 3.8 ± 2.3%, <i>P ></i> 0.05). No changes were found in FMD before or after ischaemia/reperfusion after 12-weeks in controls (<i>n</i> = 9). <b>Conclusion:</b> We found that 12-week exercise training in heart failure patients mitigated endothelial ischaemia-reperfusion injury, an effect independent of the type of exercise. These changes may contribute to the cardioprotective effects of exercise training, whilst our findings highlight the potency of exercise as a preconditioning stimulus.