Two words: "skin eruption."
Let's say you're having a pretty solid morning at the gym. You just wrapped up a sweaty set of reps, and you're feeling good about hitting a new PR. Sure, you're running a little late for a morning meeting, but that shouldn't be a problem—you can just do a shorter Ed Sheeran song in the shower. Except, shit, you forgot your flip flops. Now what?
In any shared shower facility, you're going to find the the obvious post-workout body detritus—sweat, skin cells, clumps of hair. (You should also know that one recent survey found 62 percent of people pee in the shower on a regular basis. Some environmental activists encourage shower peeing as a way to conserve water and cut down on TP use, so there's that.)
But how gross is it to forego footwear in the locker room, really? We asked Marilyn Roberts, a professor of environmental and occupational health sciences at the University of Washington School of Public Health if she would ever set foot in a shared shower facility sans flip flops.
"Uh, no," Roberts says. "If you're in a public shower anywhere, you don't have a clue who's been there, who's used it, how often it's cleaned."
She explains that the sanitation of your shower situation depends on a number of factors, most of which are outside your control. How many people are in and out each day? How clean have those people been? Did they track in outside dirt and grime on their shoes?
Because it's not just hair and sweat pooling down there on the tiled floor. What makes locker rooms a little skankier than your standard shared facility is the warm, wet environment. Many don't have good ventilation, which essentially makes it a bumpin' silent rave for fungi, mold, and bacteria. If you're regularly using the locker room without some version of a foot rubber, she says it's fairly likely that you'll eventually pick up ringworm, athlete's foot, or some other kind of fungal infection.
Roberts says any locker room that has hundreds of people traipsing in and out of it needs to get scrubbed down at least once a day, and should probably be cleaned closer to three or four times daily. This isn't just a consideration for gym-goers, either. Especially in regions like the Pacific Northwest, where she lives and teaches, shower mold is a persistent problem even in private residences because of the damp, humid climate. "God forbid you're in a fraternity house, where the bathrooms get cleaned maybe once a quarter," she says.
On the less likely but far scarier side of things, you could contract a bacterial infection such as MRSA, an antibiotic-resistant strain of staph. Athlete's foot and other toenail infections can be extremely severe.
Ultimately, if you're hitting the treadmill at a boutique gym that's cleaned by folks who are as adept at tackling pube situations as Abbi is in the Soulstice locker rooms, you're probably okay. But if you're at a YMCA or a university health center that's only cleaned once a day or once a week, you definitely want to spend a few bucks on a pair of shower shoes. Just getting your feet off the shower bottom is usually adequate when it comes to avoiding infections.
If you forgot your flops, give the showers the old eyeball test—and if they don't look clean, you're better off skipping it. If you have open cuts or abrasions, it's a definite no-go; if you're someone who's prone to infections, have had athlete's foot before or are otherwise immunocompromised, you need to take extra steps to protect yourself, and should maybe consider keeping an antifungal powder in your gym bag.
That said, there will be a day you gym-shower unprotected. It might be later today, even after you've just read this, you rebel. In this case, dry your feet off like a champ post-shower and air them out before you put your shoes back on. Roberts adds that if you develop any kind of "skin eruption"—sorry, her words—that's unlike something you've had before and doesn't go away in a few days, for the love of god, see a doctor, especially if it's hot to the touch or if you're running a fever.