A word of warning for the occasional-yogi: Don't touch that communal mat! And if you do, disinfect yourself immediately.

Studio yoga mats [1] could harbor all kinds of funky germs that you don't want on your feet or skin. In fact, that harmless-looking mat where you've rested in child's pose [2] and lain in savasana [3] might be giant petri dishes teeming with viruses, fungi and bacteria.

According to the New York Times [4], communal mats are the suspected culprits behind a marked increase in red, flaky, bumpy skin and itchy, god-awful foot rashes. Podiatrists say they've seen a 50 percent spike in patients with athlete’s foot [4] and plantar warts [5], which they attribute to unclean exercise mats. Dermatologists similarly report a higher incidence of skin rashes [5]. While the link between these ailments and yoga [5] mats is still anecdotal, but I'm convinced that shared mats are a hazard.

I assume the problem is worse at gyms, because there's a higher volume of people who sweat in general. Same goes for Bikram yoga [5], which is done in 105 degree room. (Bikram veterans know that sweat isn't the right word. It's more like you morph into a waterfall.) Theoretically, gyms wash and disinfect mats on a regular basis. I wouldn't count on it.

I got my first inkling about how truly nasty yoga mats could be a while back. I started practicing yoga [5] during the Dark Ages, which was a few months before Madonna's [6] public embrace of all things hatha. Back then, yoga mats were tough to come by. (Either that, or I was too cheap to buy one, I can't remember anymore.)

In any case, most people at that studio used communal mats. I used one too, until one very long, very disgusting class which involved several variations of plank pose [7] on a foul mat. I spent 90 minutes hovering above a bacterial breeding ground mat, trying not to breathe in a stench of old sweat, smelly feet and all the negative vibes that thing absorbed. That was a bad day. I bought my own mat before the next class.

The moral of the story? Cough up the $25 for your own mat now. It could help ensure that you won't cough up a lung later.