The presence of axillary artery aneurysm and/or thrombus in overhead throwing athletes has been linked, theoretically, with the finding of compression by the humeral head induced by a diagnostic arm maneuver. However, whether this intermittent compression is incidental or of pathological significance has yet to be determined. Flow-mediated vasodilation (FMD), intima-media thickness (IMT) and maximum vasodilatory capacity were measured locally (3rd portion of the axillary artery) and downstream (brachial artery) in individuals previously tested for inducible axillary artery compression (compressor group [COMP]: n=8, mean (SD) age: 23 (4) y; "noncompressor" control group [NONCOMP]: n=8, 26 (4) y). A high-resolution ultrasound machine recorded arterial diameter and blood flow velocity. A rapid inflation/deflation pneumatic cuff placed distal to the site of measurement induced reactive hyperemia. Custom-designed wall tracking software with synchronized Doppler waveform analysis detected changes in arterial diameter, blood flow velocity and shear rate from baseline to 3min after cuff deflation. Glyceryl trinitrate and/or ischemic hand grip exercises were administered to induce maximum vasodilation. No significant differences in FMD, IMT or maximum vasodilator capacity were observed between groups at the axillary artery. However, the downstream brachial FMD response was significantly diminished in the COMP group (6.38 [3.28]%) compared with the NONCOMP group (10.38 [2.74]%; p=0.006) despite a comparable shear rate between groups (COMP: 81.92 (44.55) s(-1); NONCOMP: 83.18 (40.02) s(-1); p=0.961). Pooled data revealed a significant negative relationship (r=-0.52, p=0.038) between the FMD response and degree of arterial compression. These results suggest a chronic change in downstream vascular function in individuals demonstrating clinically significant inducible axillary artery compression.