You've put in the months of training and splurged on the latest moisture-wicking kit. While the marathon course isn't a runway, avoid committing one of these fashion atrocities on your big race day (or any day for that matter).
Vibrams with socks: Aesthetically, the five-toe look has its challenges, but pairing it with socks is a crime against humanity. Spare the world.
Ill-fitting or low-intensity sports bras: Ladies, reel in excessive bouncing with a good sports bra. Shelf bras or sports tops only work for smaller busts, or for women pairing them with a sports bra underneath. If you find your sports bra itchy, too stretchy, unsightly, or (gasp) you wind up wearing two to get the support you need, check out Lululemon's Ta Ta Tamer II, Moving Comfort's Fiona, and models from Lynx and Enell.
Lacy, thong, or cheeky underwear, especially if it shows: FitSugar advises opting for full-coverage wicking underwear such as those from Isis. It's not a sexy look, but it gets the job done. Also moisture-wicking socks are a must, so check out those from Smartwool, Thorlo, and Teko.
Tucking in a t-shirt: Runners don't tuck, ever, Runner's World advises. Rather, opt for a top that fits nice and snug against the body.
Shirtlessness: Resist the urge to strip off your t-shirt the minute the mercury creeps up, Runner's World says. For autumn running, perfect the art of layering in lightweight performance gear.