Athletes in the know [like Dwight Howard, above] don’t wear regular cotton T-shirts when they train. Instead, they sport moisture-wicking apparel, which keeps them dry and comfortable—and free to focus on performance.
Most moisture-wicking athletic apparel is made of synthetic material, like nylon, polyester or spandex. These fabrics work better than cotton because they absorb moisture, then quickly dry out. Cotton also absorbs moisture, but does not dry quickly, often leaving athletes in a dripping wet shirt.
Livestrong.com notes that moisture-wicking materials also help reduce chafing, which is particularly important for constantly moving athletes, who would be bothered by fabric repeatedly rubbing against their skin. Plus, since they are lighter and more breathable, the wicking materials keep you cooler than cotton in hot temperatures.
During winter, the fabrics help prevent weather-related conditions like hypothermia. Lingering sweat can severely chill athletes in cold temperatures. Avoid this potential hazard by investing in a long-sleeved, moisture-wicking shirt, which will also provide extra warmth.
Depending on the brand and type of shirt, you’ll spend approximately $20 to $40. This is a reasonable investment considering the long-term usability and benefits of the product. Stay safe and comfortable by picking up a moisture-wicking shirt before your next workout.
Source:  Livestrong.com