Aside from setting and surpassing personal goals, the thrill of competition is a large part of what's made Nike+ so successful. Starting today, the company's Nike+ Running app for iOS is offering yet another way for friends to one-up each other: challenges. A step beyond the leaderboards already available to users, challenges let you agree upon a target distance and invite fellow runners to see who can get there first.

In an effort to increase motivation, Nike is even giving challenge participants access to an exclusive group chat feature. Anyone involved in a given challenge can message other runners in real time to provide inspiration or perhaps some friendly smack talk. Nike also plans to bestow a virtual medal upon challenge winners — a reward with zero real-world significance, but likely a source of bragging rights all the same. The latest Nike+ Running update is available now in the App Store, though challenges haven't made their way to Android just yet.