Daphney M. Stanford, Brianna N. Cupp, Matthew A. Chatlaong, Matthew B. Jessee. University of Mississippi, Oxford, MS.

BACKGROUND: Ischemic preconditioning (IPC) typically improves vascular health, but it is unknown if a non-ischemic protocol would have a similar acute stimulus. The purpose of this study was to compare the acute hyperemic response of IPC and blood flow restriction (BFR). METHODS: 20 subjects (45% female) completed 3 conditions over 3 visits (randomized and counterbalanced). While supine, a pneumatic cuff was placed on the upper right arm, and following 5min rest, arterial occlusion pressure (AOP, mmHg) was measured, then following a second 5min rest the protocol started. For IPC, a cuff inflated (105%AOP) for 5min with 5min of rest for 4 cycles. For BFR, a cuff inflated (80%AOP) for 5min with 3min rest for 5 cycles. CON had a deflated cuff on for 40min. Using duplex ultrasound distal to the cuff, brachial artery blood velocity (cm/s) and diameter (cm) were recorded at baseline (Pre) and after cuff deflation. The first 30s of blood velocity after cuff deflation was averaged, and the last 30s of artery diameter after cuff deflation was averaged. AOP was measured immediately after (Post) the protocol. Discomfort (DIS, A.U.) was asked with a 0-10 scale at Pre and Post. Changes in artery diameter and blood velocity (last cycle-Pre), and changes in AOP and DIS (Post-Pre) were compared across conditions using Bayesian repeated measures ANOVAs. Results presented as mean±SD. BF10=likelihood of the best model vs the null. RESULTS: The change in artery diameter (Condition: BF10=400.697) for BFR (.01±.02) was higher than CON (-.01±.02; BF10=2.651), and lower than IPC (.02±.03; BF10=1.569). IPC was higher than CON (BF10=82.853). The hyperemic response (Condition: BF10=5.887e+15) for BFR (6.7±7.3) was higher than CON (-3.1±5.1; BF10=148.630), and lower than IPC (34.2±14.2; BF10=156409.519). IPC was higher than CON (BF10=3.128e+7). The change in AOP (Condition: BF10=1.296) was higher in BFR (-8.95±10.83) when compared to CON (-2.26±9.69; BF10=1.268), but similar to IPC (-6.53±5.81; BF10=.345). IPC and CON were similar (BF10=.576). The change in DISC (Condition: BF10= 19526.876) was higher in BFR (4.08±2.6) when compared to CON (1.3±2.1; BF10=195.289), but similar to IPC (4.03±2.63; BF10=.244). IPC was higher than CON (BF10=141.363). CONCLUSION: Individuals may want to implement bouts of IPC instead of BFR for vascular health because the acute stimulus is stronger while the discomfort is similar between protocols.

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