I read a magazine article about differences in how men and women use their backs while lifting. There was also some information about the differences between people who have hurt their backs compared to people who haven't. How do scientists get this information?

There are entire laboratories devoted to the study of human movement. Today's technology allows researchers to place electrodes on muscles to record electrical activity. Researchers then use this information to make calculations. Other systems use today's new optical technology to record body motion down to a "nanosecond," one billionth of a second.

New equipment is available to measure movement when the body is placed in certain positions. The same movement can be observed outside the apparatus to show how the body works to adjust for back pain.

There are even ways to measure how much force is placed through the spine with different movements or when lifting different weights. The person being tested stands on a platform called a force plate that provides this kind of information. Again, various measurements can be taken as the person lifts and moves.