Since compression shorts are similar in design and in purpose to bike shorts, they are designed to be worn next to skin without any underwear. Wearing underwear underneath compression shorts will take away some of the benefits of wearing them such as friction reduction and the ability to wick away moisture.
As the name implies, compression shorts are a type of athletic garment made from an elastic fabric that compresses and fits snugly around the thighs, buttocks and even the calf muscles for longer compression garments. These garments are usually made 15 percent smaller than regular sizes to ensure a tight fit. Compression shorts are a popular workout apparel for both competitive athletes and fitness enthusiasts.
Wearing compression shorts supposedly provides a number of health benefits, especially for physically active individuals. Some believe that the compression from the shorts gives added support to the quads, hamstrings and glutes, as well as encouraging more blood flow to the compressed area. The added blood flow may promote faster recovery after training. There are those who wear compression shorts to minimize friction and chafing.
For some people appeal of wearing compression shorts stem from the belief that the tight undergarment also helps in improving their physical performance. A 2011 study in Occidental College in Los Angeles seemed to support this belief. In the study, runners were able to jump higher with less exertion while wearing compression shorts.