Effects of Recurring IPC vs. rIPC Maneuvers on Exercise Performance, Pulse Wave Velocity, and Red Blood Cell Deformability: Special Consideration of Reflow Varieties

SIMPLE SUMMARY: Ischemia preconditioning (IPC) and remote (r) IPC consist of a sequence of blood occlusion and blood reflow to manipulate an effector organ either near (IPC) or remote (rIPC) from the occlusion site. Its benefits in medical applications are well-documented, while there is no consensus regarding its effects on exercise performance, arterial stiffness, blood pressure, and red blood cell deformability. The aim of the study was to test and compare the effects of five daily recurring IPC and rIPC maneuvers on these parameters. Additionally, different reflow protocols, low (LR) and high reflow (HR), were compared to investigate potential differences of the shear stress occurring during reflow on the outcome. Results of thirty male participants suggest improved exercise performance during IPC LR and to a lesser extent rIPC LR interventions, while HR conditions did not affect performance parameters. This might in part be related to increased red blood cell deformability and reduced lactate production, while relations to altered pulse wave velocity or blood pressures seem less likely. In conclusion, the site of occlusion and reflow conditions might influence the effectiveness of the (r)IPC intervention, which should be considered in sport-specific but also clinical settings. ABSTRACT: Beneficial effects of (remote) ischemia preconditioning ((r)IPC), short episodes of blood occlusion and reperfusion, are well-characterized, but there is no consensus regarding the effectiveness of (r)IPC on exercise performance. Additionally, direct comparisons of IPC and rIPC but also differences between reflow modes, low reflow (LR) and high reflow (HR) in particular, are lacking, which were thus the aims of this study. Thirty healthy males conducted a performance test before and after five consecutive days with either IPC or rIPC maneuvers (n = 15 per group). This procedure was repeated after a two-week wash-out phase to test for both reflow conditions in random order. Results revealed improved exercise parameters in the IPC LR and to a lesser extent in the rIPC LR intervention. RBC deformability increased during both rIPC LR and IPC LR, respectively. Pulse wave velocity (PWV) and blood pressures remained unaltered. In general, deformability and PWV positively correlated with performance parameters. In conclusion, occlusion of small areas seems insufficient to affect large remote muscle groups. The reflow condition might influence the effectiveness of the (r)IPC intervention, which might in part explain the inconsistent findings of previous investigations. Future studies should now focus on the underlying mechanisms to explain this finding.