Lots of gross things (unsurprisingly) live in your running shoes.
"Quite simply, running shoes are petri plates we put on our feet," Tetro says. "They are destined to be infused with bacteria and fungi."
Constant exposure can lead to athlete's foot—an itchy and flaky rash on your toes and feet—or a fungal infection of the toenail; a condition called onychomycosis.
How do you know if you are the lucky recipient of onychomycosis?
Alternating between pairs of running shoes to give them time to air out can protect your feet from fungus.
Infected toenails become thickened, brittle, distorted in shape and color and can sometimes separate from the nail bed, according to the Mayo Clinic.
To clean your stenchy shoes, Tetro suggests washing them with water and detergent and air or fan dry them. The American Academy of Dermatology even recommends an ultraviolet shoe sanitizer, a light device you put inside the shoe to kill germs.
Wearing moisture-wicking socks and alternating between pairs of running shoes to give them time to air out can also protect your feet from fungus.
Dr. Lisa Ackerley, a hygiene expert with a website called "The Hygiene Doctor," recommends spritzing the inside of the shoes with a disinfectant spray from time to time—especially if you just had athlete's foot. Otherwise, you can re-infect yourself.
How should I deal with my dirty laundry?
Don't let that damp pile sit inside your hamper too long.
"Any germs picked up in the gym or from your body will be given an ideal place to multiply," Ackerley says. In addition to bacteria, your clothes can grow mold if left long enough. Be sure you wash your hands after tossing the clothes in the washer, as well.
Chemicals and/or heat are the best way to get rid of the germs. Tetro says an environmental temperature of 160 degrees or higher kills all forms of microbes.
"Whether it's the washer or the dryer, keeping them in this temperature for at least three minutes will do the trick," he says. "It's often tempting to wash active wear at low temperatures because that's what is says on the label." But if you choose to do that, use a laundry powder with oxidative bleach or throw in an anti-bacterial laundry additive.
Bottom line? The worst problem your sweaty running gear will likely cause is a putrid odor, but if you don't want to offend your running buddies—or contract some sort of weird skin "thing"—get into the habit of treating your active wear and shoes with care.
Find your next race.