Vascular adaptations to blood flow restriction resistance training with different cuff types: the role of retrograde shear stress.

Purpose: Narrow-elastic bands (NE) and wide-rigid cuffs (WR) are two types of cuffs that are frequently used in blood flow restriction (BFR) training. Because these cuffs produce different hemodynamic responses, vascular adaptations might differ depending upon what cuffs are used. We examined the hypothesis that BFR with NE would improve vascular function while BFR with WR would decrease vascular function.

Methods: Twenty-six young healthy participants completed supervised BFR training for 2 weeks with NE placed on one arm and WR on the other arm during upper-body resistance exercise using random arm allocation with counterbalancing across the participants. Flow-mediated dilation (FMD), arterial stiffness, muscle strength, and muscle mass in both arms were measured before and after the intervention. To explore possible mechanisms underlying vascular adaptations, retrograde shear rates (SR) induced by different cuffs in the brachial artery were also measured before the intervention.

Results: Muscle strength increased in both arms (p < 0.05). FMD increased in the NE arm (5.6 ± 2.9 to 7.7 ± 3.4%, p = 0.004) but did not change in the WR arm (6.0 ± 2.5 to 4.9 ± 2.7%, p = 0.12). Retrograde SR was higher under WR occlusion compared with NE occlusion and no cuff (no cuff: 22 ± 9, NE: 25 ± 9 vs. WR: 39 ± 13 s^-1, p < 0.001). A negative correlation was found between WR occlusion-induced changes in retrograde SR and relative changes in FMD (r = -0.42, p = 0.02).

Conclusion: Different BFR cuffs led to similar muscle adaptations but different vascular adaptations. The difference in the vascular adaptation between two different cuffs might be explained by a greater retrograde SR induced by WR occlusion.