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

Studio yoga mats 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 and lain in savasana might be giant petri dishes teeming with viruses, fungi and bacteria.

According to the New York Times, 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 and plantar warts, which they attribute to unclean exercise mats. Dermatologists similarly report a higher incidence of skin rashes. While the link between these ailments and yoga 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, 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 during the Dark Ages, which was a few months before Madonna's 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 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.