People sitting and working for a longer period of time at a stretch are affected by pain in the joints and also with piles, people who are standing and working for a longer period of time are affected by the diseases of the legs called varicose veins.
Normally all most all police personnel especially traffic cops, teachers, servers and nurses whose nature of job itself is to stand and work are affected by varicose veins.
By nature animals are equipped with the ability to stand on their four legs. So when the animals are standing and walking or running their body weight is distributed in an even way and borne by the earth.
But in view of the fact that human beings are equipped with two legs only, they are standing in opposition to the force of the gravity. So naturally when we work for long hours at a stretch in a standing position, then the small blood vessels and the valves connected with it in our legs comes under pressure.
The pure blood from our heart travels to all the parts of our body including legs. So naturally it should go back to the lungs and the heart for purification.