Why Uruguay's World Cup Uniforms Are Ridiculously Tight

Uruguay's World Cup kit is made of a skin-tight fabric that shows every vein and muscle on a player's body.

We've seen tight uniforms from Puma — which sponsors Uruguay, Italy, and some other national teams — at previous World Cups. But this takes it to a new level.

It seems like it would be incredibly uncomfortable, especially in the heat, but the tight design actually serves a function, according to Puma.
<snip>

The company explained it in a press release:

"The ACTV tape is strategically placed within the garment to provide micro-massages on the skin, working with the human body to help maximise performance and provide players with a faster, more effective energy supply to the active muscles. This combined with the underarm mesh inserts for increased breathability and freedom of movement, will help Uruguay have a competitive advantage at this year’s World Cup."
<snip>

http://www.businessinsider.com/uruguay-world-cup-uniform-tight-2014-6

It's not just Uruguay. I've seen these shirts on many teams. We've come a long way from the baggy shirts of the 90's.