Gravity is a tricky customer. While the forces of gravity may keep our planet in orbit around the sun, our feet on the ground, and basketballs from knocking our teeth out as they rebound into space, it also can lead to some discomfort as it tries to pull the mass of our bodies into the core of the earth.
Even sitting around doing nothing can be tiring. Your head weighs about 12 pounds, the same as an average bowling ball, and all of that mass has to be supported by your spinal column. Your arms are held on by the sinews in your shoulders, and your entire upper torso and abdomen, the bulk of your weight, sits on top of your pelvis.
When you fall asleep sitting up, you injure your neck and upper back. When you have bad posture, you injure your upper and lower backs. When you sit in one place for too long, your butt goes numb. When you stand in one place for too long, your feet start to ache. Only by lying down, dispersing our weight over as much of the earths surface as possible, can we find any rest.
People who sit in front of computers almost every day of their lives and there are hundreds of millions of us who do are prone to a number of gravity fed, or repetitive stress injuries.
Our backs and necks are sore from all the sitting we do. Our elbows, wrists and fingers are sore from all of the typing and mouse clicking that are part of our daily routines. Now secretaries that type 100 words a minute are discovering that their wrists and fingers are frozen from carpal tunnel syndrome. Techies who use the mouse are experiencing pain in their elbows and wrists.
Small wonder. At no time in our evolution (sorry creationists) did our ancestors sit around for eight hours a day word processing, and as a result were poorly adapted for it. An insect with a hard exoskeleton and no tendons would probably be better off.
The field of ergonomics loosely defined as the science of design that reduces the stresses that occur as a result of the objects we use, the environments we work, travel and play in is particularly challenged by the problems facing office types. An office with staff suspended horizontally by cables over ergonomically designed keyboard and mouse devices just doesnt look professional. Neither do work stations designed like Apollo era space capsules.
Children working on computers at home are also prone to injuries as a result of repetitive motions and bad posture, especially if they spend hours every day at the computer after spending a full day at school. To make matters worse, computes arent designed for pre-pubescent wrists and fingers, and may actually be worse for kids than adults.