How will under armour/compression shorts help me?

Question

I run cross country and I always see people with the compression shorts on under their uniform shorts. How does it help them and does it improve time?

Answer 1

Keeps muscles warm, helps keep sweat away from body, can help reduce muscle soreness/swelling, etc.

gf

Answer 2

Keeps your leg muscles (quads, hamstrings) warm; not sure if it has a direct impact on times or not.

Answer 3

keeps muscles warm and gives more aero-dynamics.

Answer 4

Yes they will help you run races faster. Under Armour is the only kind I wear now.