Occlusion training involves completely stopping blood flow into an extremity for substantial periods of time. It can damage tissue distal (below) to the occlusion. Completely occluding a limb for a substantial period of time increases the risk of blood clots in veins. Deep venous thromboses (DVT’s) can lead to pulmonary emboli, which can be fatal. Occlusion training can also lead to rhabdomyolysis (severe breakdown of muscle fibers), which can lead to kidney failure and possibly death.