Cotton vs Synthetic

I'll just say it... It drives me crazy when I see people running in cotton t-shirts. If they only knew how that 1 simple element was slowing them down they would surely look into buying a synthetic shirt. If you're like me, you need all the help you can get. Well folks, there is help out there.

Have you ever tried to buy a cotton running shirt from your local running store? Have you ever seen the people in the Olympics, or the winner of the Boston Mmarathon running in a cotton tee.  Guess what?  You won't. Ever! It's all about performance.

Here are the simple rules about synthetics and cottons. A fabrics breathability is measured by how much cubic feet of air flows through that fabric in one minute. It is measured in (CFM) cubic feet per minute.
A garbage bag has a breathability rating of 0 (cfm). A cotton T-shirt has a breathability rating of 30 (cfm). A synthetic T-shirt has a breathability rating of 150 (cfm). The end result is that your body is allowed to breath, which means it can sweat efficiently which allows your bodys core temperature to stay down.

Weight seems to be an issue with a lot of runners. Most people wear racing shoes that are lighter than their training shoes. Lets compare weight between a cotton shirt and a synthetic shirt. A standard cotton T-shirt weighs around 8.5 oz.  A standard synthetic T-shirt weighs around 4.5 oz.  Almost half as much and the difference is even more when the shirt is wet since cotton holds more water. Synthetic materials were designed to move moisture away from your skin, channeling the moisture to a greater area of surface, so that evaporation can occur more rapidly.  Believe it or not, wearing a synthetic shirt will actually keep you cooler than wearing no shirt at all. 

Right now your asking what the catch is. Here are the downsides to a Synthetic shirt. Synthetics cost more. You should be able to buy a shirt for around $30.00.  They also tend to hold odor worse. A trick I have learned over the years is to wash my synthetics in the normal detergent, but add a cup of baking soda to the wash. This seems to cure it for a while.

From my window at work, I see runners all day long.  I'm pretty sure that the people that have smiles on their faces are those that are wearing synthetic t-shirts.

Matt Sims
Patagonia