Looking forward to July 4th, I came across this article by James H. Warner, a Marine Corps Officer who spent five years and five months in a North Vietnamese prisoner of war camp:

the first of June, I was put in a cement box with a steel door, which sat out in the tropical summer sun. There, I was put in leg irons which were then wired to a small stool. In this position I could neither sit nor stand comfortably. Within 10 days, every muscle in my body was in pain (here began a shoulder injury which is now inoperable). The heat was almost beyond bearing. My feet had swollen, literally, to the size of footballs. I cannot describe the pain. When they took the leg irons off, they had to actually dig them out of the swollen flesh. It was five days before I could walk, because the weight of the leg irons on my Achilles tendons had paralyzed them and hamstrung me. I stayed in the box from June 1 until Nov. 10, 1969. While in the box, I lost at least 30 pounds.