When running, underwear serves as a base layer for your skin. The moisture that you lose through sweating is efficiently withdrawn from the base layer and drained to the outside of the clothing. Perhaps the most important thing about running underwear is that it fits well with your body and you are not bothered by it, especially during exercise. In the winter, running underwear must mainly ensure that your body heat is preserved and it is smart to work with the three-layer system. For example, you can opt for a good undershirt, a normal running shirt and a running jacket on top.
Besides the regular underwear there is also compression clothing for runners. The compression clothing for both upper and lower body is available from different brands, in different colors and of course, also sizes. Running underwear are available from the brands' Craft, Falke and Newline, among others.