Expert: Sue Kayton Date: 7/15/2008 Subject: pounds of pressure on lower back
Question If I lift ten pounds off the floor and my uppor torso weights 105 pounds, how many pounds of pressure am I putting on my lower back?
Answer People don't put "pounds" of pressure on their back. They put "pounds per square inch" on their backs. You'd need to know the area of the disk in your vertebra. Each vertebra is a slightly different size. Let's assume the disk is 2 square inches in area.
Once you are standing straight up, your qeight is pushing straight down on your disk. You probably weight about 300 pounds if your upper torso weighs 105 pounds. A person who weighs 200 pounds probably has an upper torso weight around 70 pounds.
If indeed your upper torso weighs 105, then you are carrying 105+10=115 pounds on that disk. 115/2 = 57.5 pounds per square inch.
But when you are bent over, there is a bending moment, also called a torque, that twists on your back. Torque is measured in different units, usually foot-pounds.
