Interval exercise, but not endurance exercise, prevents endothelial ischemia-reperfusion injury in healthy subjects

Endothelial ischemia-reperfusion (I/R) injury importantly contributes to the poor prognosis during ischemic (myocardial) events. Preconditioning, i.e., repeated exposure to short periods of ischemia, effectively reduces endothelial I/R injury. In the present study, we examined the hypothesis that exercise has preconditioning effects on endothelial I/R injury. Therefore, we studied whether an acute bout of endurance or interval exercise is able to protect against endothelial I/R injury. In 17 healthy young subjects, we examined changes in brachial artery endothelial function using flow-mediated dilation (FMD) before and after a bout of high-intensity interval exercise, moderate-intensity endurance exercise, or a control intervention. Subsequently, I/R injury was induced by inflation of a blood pressure cuff around the upper arm to 220 mmHg for 20 min and 20 min of reperfusion followed by another FMD measurement. Near-infrared spectrometry was used to examine local tissue oxygenation during exercise. No differences in brachial artery FMD were found at baseline for the three conditions. I/R induced a significant decline in FMD (7.1±2.3 to 4.3±2.3, P<0.001). When preceded by the interval exercise bout, no change in FMD was present after I/R (7.7±3.1 to 7.2±3.1, P=0.56), whereas the decrease in FMD after I/R could not be prevented by the endurance exercise bout (7.8±3.1 to 3.8±1.7, P<0.001). In conclusion, a single bout of lower limb interval exercise, but not moderate-intensity endurance exercise, effectively prevents brachial artery endothelial I/R injury. This indicates the presence of a remote preconditioning effect of exercise, which is selectively present after short-term interval but not continuous exercise in healthy young subjects.