Wearing compression tights enhances overall circulation to the legs and therefore decreases energy expenditure at prolonged speeds. Long-distance runners also benefit by staving off tired runner's legs when you have longer runs or races planned, potentially giving you an extra edge.

Why do runners run in spandex?

Compression gear, usually made of 80% nylon and 20% spandex, conforms snugly to the body preventing oscillation of the muscle during impact and increasing blood flow to the area.

Why do sprinters wear tight clothes?

The slim fit of tights provides the obvious yet crucial benefit of not riding up during a run. In addition, the tightness will eliminate friction that baggier clothing can cause against your skin.