Boot leg warmers are usually worn underneath boots with the tops of the leg warmers showing above the boots. Leg warmers are sometimes worn with boots to disguise a gap in the fit of a boot around a slim calf. In this case, leg warmers are pulled to the top of the boot then slid down in a messy manner to create a bulky look.
Leg warmers are similar to socks but generally do not have feet. They were first worn by ballet dancers to keep leg muscles warmed up to prevent injuries and cramps, but no scientific evidence supports the assertion that leg warmers decrease the incidence of injuries. Some leg warmers intended specifically for use by dancers have feet with nonslip pads on the soles.
The garments are often knitted from wool or are made of synthetic fibers or cotton. They vary in size and level of stretchiness. They are usually worn between the ankle and the knee, though some people wear them up to the middle of the thigh. Short leg warmers made of thin material are called ankle warmers.
Leg warmers became a fad in the 1980s, due in part to the box-office success of the 1983 movie "Flashdance," in which Jennifer Beals portrays an aspiring dancer. The aerobics fitness craze of the 1980s also prominently featured leg warmers, contributing to their popularity.