Consumer Watch: How to keep your gym clothes fresh

FRESNO, Calif. (KFSN) -- You may look great wearing those new workout clothes, but after a few visits to the gym, they might not smell so great.

But don't worry, Consumer Reports says it's not you. It is the fibers in stretchy fabrics that hold in the odor.

"Sweat evaporates, but what's left behind are odor-causing chemicals on the surface of the synthetic fibers," says Consumer Reports Home Editor Haniya Rae. "They can be difficult to wash out, and they can build up over time."

Part of the challenge in getting workout clothes clean is that some of them are made from more delicate fibers, and may need special care to protect their shape and fit.

So what can you do to keep your leggings and t-shirts in tip-top shape? First, try to wash them as soon as you finish working out.

"Keeping these synthetics bunched up and damp promotes bacterial growth, which gives off odors, making them smell even worse," Rae said. "Pretreat any stains and turn them inside out. This allows the water and detergent to focus on the soils that have accumulated on the inside of your clothes."

Washing in cold water prevents fading and preserves the fit of these synthetic fibers.

Choose the gentle cycle and if your washer has an extra rinse cycle, use it. Be picky about which detergent you use.

"Our tests have found not all detergents are up to the task," Rae said. "The chemicals in sweat and body oil are especially difficult to remove, and can actually attract other soils that increase odors."

CR's testing of laundry detergent finds Tide Plus Ultra Stain Release is excellent at removing body oil.