Subject factors influencing blood flow restriction in the arm at low cuff pressures

Abstract

BACKGROUND Limb circumference predicts the pressure needed for complete occlusion. However, that relationship is inconsistent at moderate pressures typical of effective blood flow restriction (BFR) training. The purpose of this study was to investigate the influence of subject factors on BFR at low restriction pressures in the arm. METHODS Fifty subjects had arm anthropometrics assessed by peripheral quantitative computed tomography (pQCT), skin folds (sumSKF) and Gulick tape (GulCirc) at cuff level. Blood flow was measured with ultrasound at baseline and five restrictive pressures (20,30,40,50, and 60mmHg). Relationships between subject characteristics and BFR were assessed using Pearson correlations and hierarchical regression. RESULTS Blood flow decreased (p<0.05) at each incremental pressure. Regression models including muscle composition (%Muscle), pQCT circumference, and systolic blood pressure (SBP), were significant at all 5 pressures (R2 = 0.18 to 0.49). %Muscle explained the most variance at each pressure. Regression models including sumSKF, Gul circ, and SBP, were significant at 30–60mmHg (R2 = 0.28 to 0.49). SumSKF explained the most variance at each pressure. CONCLUSIONS At low pressures (20–60mmHg), there is considerable variability in the magnitude of BFR across individuals. Arm composition factors (muscle, fat) explained the greatest variance at each cuff pressure, and may be the most important consideration when using BFR protocols.