Practical BFR is the use of pneumatic tourniquets to allow arterial blood flow to a region while limiting venous return during exercise. It utilizes Doppler Ultrasound to find the limb occlusion pressure (LOP) to individualize pressures to the individual.
A reduction in arterial blood flow is NOT occlusion training, and reduces the oxidative capacity of the muscles. With less oxygen to work with, the body quickly shifts to higher threshold Type II muscle fibers in an attempt to complete the workload you desire. Venous pooling leads to accumulation of metabolites such as hydrogen ions from the breakdown of ATP (our main energy compound) and lactate. This metabolic stress accumulation leads to a robust anabolic microenvironment that leads to the systemic benefits in the chart below.