Over the last few years Nike has produced several versions of its Nike Pro line of athletic apparel.  This started as the Nike Pro Basic, then there was the Nike Pro Vent line, introduced with the Michael Vick advertising campaign.  Since then Nike has produced several variations of its Nike Pro line, short sleeve and long sleeve, all centered around the idea of a moisture wicking fabric to help reduce sweat and increase atletic performance.

Under Armour was the pioneer of this technology and has several competing lines with Nike, here is a good review of under armour .  The theory behind the technology is that by creating a moisture wicking fabric sweat build-up on the skin would be removed off the skin to the outer layer of the garment for quicker evaporation.  This helps to cool the athlete while allowing them to continue to exercise.  The second part of the technology is to incorporate a skin tight compression fit.  This helps to keep the muscles in place, making them more efficient.

As an athlete, I, myself have worn both Nike and Under Armour clothing and have found that there is an advantage gained when wearing the various moisture wicking fabrics.  Nike produces a winter line of its Nike Pro series which I have worn as a base layer while snowboarding.  It not only provides warmth, but also removes sweat off your body helping to prevent you from getting cold.  After the first time I went snowboarding, I was sold.

When it comes to fit, the best guide is to wear your t-shirt size.  The "tight fit" versions of the shirt are designed to have a second skin fit and are very snug.  They should not be so constricting that they make it hard for you to breathe, but they should be tight on the skin.  An additional picture fit guide is provided:


Just as Speedo has done for swimmers, Nike has provided the every-day athlete availability to new technologies to perform at a higher level and for a longer time through it's nike pro line of clothing.