Blood Flow Restriction Training in Athletes: Endothelial Phenotype, Thromboembolism Risk, and Tailored Safety Protocols.

Low-load blood flow restriction (LLBFR) training has gained traction as a rehabilitation and performance tool, offering muscle strength and hypertrophy adaptations comparable to high-load resistance training while minimizing joint and tissue stress. However, its application in athletes at risk for venous thromboembolism, post-thrombotic syndrome (PTS), inherited thrombophilia, and special populations (pregnant competitive female athletes and paralympic athletes with spinal cord injury) raises safety concerns. This narrative review synthesizes evidence on LLBFR's hemodynamic and endothelial effects, highlighting pressure-dependent basal lamina thickening, impaired flow-mediated dilation, and transient elevations in peripheral venous pressure. It emphasizes the importance of pre-exercise risk stratification, genetic screening for factor V Leiden and prothrombin mutations, and assessment of cardiovascular and coagulation markers. For athletes with confirmed deep vein thrombosis, PTS, or multiple risk factors, LLBFR should be contraindicated. In paralympic athletes with spinal cord injury, stringent exclusion criteria (e.g., severe autonomic dysreflexia, pressure ulcers) are essential, whereas female athletes may require individualized monitoring of coagulation changes during oral contraceptive use and pregnancy. Although LLBFR shows promise for preserving muscle function when traditional loading is impractical, robust, large-scale studies measuring thrombogenesis and fibrinolysis markers are urgently needed. Tailored protocols that balance musculoskeletal benefits against thrombotic risks will ensure safe, effective implementation across diverse athlete populations.