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Two‐Weeks of Remote Ischemic Preconditioning Alters Sympathovagal Balance

Remote ischemic preconditioning (RIPC), elicited by brief, intermittent periods of ischemia followed by reperfusion, has cardioprotective effects. Our lab recently found that repeated bouts of RIPC improves microvascular function; however, it is unclear whether autonomic function would also be affected. We hypothesize that heart rate variability (HRV) will be altered following two weeks of repeated RIPC. Eleven healthy adults (age = 22 ± 2 yrs, 6 males, 5 females, BMI = 23.1 ± 3.4) performed two weeks of RIPC over 3 four‐day periods, each separated by a one‐day break. Each RIPC session consisted of 4 repetitions of 5 minutes of arm blood flow occlusion interspersed by 5 minutes of reperfusion. Before and one day after two weeks of RIPC, resting heart rate was collected with lead II electrocardiogram (ECG) while the participant was comfortably lying in a semi‐recumbent position in a quiet, dimly lit thermoneutral environment. Power spectral density and symbolic dynamics were used to assess HRV from ~350 beat ECG segments. Two weeks of repeated RIPC decreased the percentage of 0V beat fragments (pre‐RIPC = 13.1 ± 6.5%, post‐RIPC = 6.9 ± 4.9%, P < 0.05) and increased the percentage of 2V beat fragments (pre‐RIPC = 42.9 ± 12.1%, post‐RIPC = 52.5 ± 10.0%, P < 0.01), while decreasing the LF/HF ratio (pre‐RIPC = 1.1 ± 0.6, post‐RIPC = 0.7 ± 0.3, P < 0.01). Thus, both the spectral and fractal analyses indicate that repeated RIPC shifts sympathovagal balance by increasing parasympathetic and decreasing sympathetic activity.