How does blood travel from the veins in the lower extremities to the heart?

There are 3 ways blood moves its way up to the heart from the legs.
   1. Valves: The veins have very low pressure so the blood needs a little help getting back into the heart. There are small valves in the veins that only allow the blood to move one way, and stops the blood from back flowing. Think of it as a salmon ladder for your blood.

   2. Skeletal muscle pump: All your veins are surrounded by muscles, When muscle contracts it gets wider and puts pressure on the veins which forces the venous blood up. The more you move the easier venous blood moves back to the heart.
   3. Respiration: When you breath in and out it will change the pressure inside the body. When the pressure changes in your thorax it pulls and pushes the blood in the veins. Because of the valves the blood doesn't flow back and continuously moves up back toward the heart.