As a first responder, they teach us to lay the patient in a "W" position once they are on the ground, and leave them in that position during transport. Then, we slowly loosen the straps on their harness as to gradually reintroduce the pooled blood in their legs to the rest of the body.
The pooled blood is oxygen deficient and contains toxins that could cause BIG problems -- heart dysrhythmia, kidney damage, etc. The same problems can occur with removal of tourniquets, which is one reason why we never remove tourniquets in the field.
