I'm not sure I could ever finish a marathon, let alone log 26.2 miles while running backwards. But people have done it -- run marathons backwards, that is.

Ask Miles from Runner's World says more runners than we'd think have finished in this manner. In March, Rome held a backward marathon with 44 registered runners. And in 2004, Chinese runner Xu Zhenjun ran a 3:43:39 backward marathon. I'm dizzy just thinking about it. And pretty impressed too.

Got any backward fitness feats up your sleeve?