Cardiac autonomic recovery following traditional and augmented remote ischemic preconditioning

Purpose While the possible ergogenic benefits of remote ischemic preconditioning (RIPC) make it an attractive training modality, the mechanisms of action remain unclear. Alterations in neural tone have been demonstrated in conjunction with circulatory occlusion, yet investigation of the autonomic nervous system following RIPC treatment has received little attention. We sought to characterize alterations in autonomic balance to both RIPC and augmented RIPC (RIPCaug) performed while cycling, using acute and sustained autonomic indices. Methods Thirteen participants (8M:5F) recorded baseline waking heart rate variability (HRV) for 5 days prior to treatment. Participants then completed control exercise (CON), RIPC, and RIPC(aug)interventions in a randomized cross-over design. Cardiovascular measurements were recorded immediately before and after each intervention at rest, and during an orthostatic challenge. Waking HRV was repeated the morning after each intervention. Results RIPC resulted in acutely reduced resting heart rates (HR) ( increment - 4 +/- 6 bpm,P = 0.02) and suppressed HR 30 s following the orthostatic challenge compared to CON (64 +/- 10 vs 74 +/- 9 bpm,P = 0.003). RIPC(aug)yielded elevated HRs compared to CON and RIPC prior to (P = 0.003) and during the orthostatic challenge (P = 0.002). RIPC(aug)reduced LnSDNN (Baseline 4.39 +/- 0.27; CON 4.44 +/- 0.39; RIPC 4.41 +/- 0.34; RIPC(aug)4.22 +/- 0.29,P = 0.02) and LnHfa power (Baseline 7.82 +/- 0.54; CON 7.73 +/- 1.11; RIPC 7.89 +/- 0.78; RIPC(aug)7.23 +/- 0.87,P = 0.04) the morning after treatment compared to all other conditions. Conclusions Our data suggest that RIPC may influence HR acutely, possibly through a reduction in cardiac sympathetic activity, and that RIPC(aug)reduces HRV through cardiac vagal withdrawal or increased cardiac sympathetic modulation, with alterations persisting until the following morning. These findings imply a dose-response relationship with potential for optimization of performance.

Automated summary

The study found that RIPC may affect heart rate acutely by reducing cardiac sympathetic activity, while RIPC(aug) reduces HRV through cardiac vagal withdrawal or increased cardiac sympathetic modulation, with effects persisting until the following morning.