With the Adidas MiCoach upping the fitness game for phones, Nike has returned fire with an updated version of the Nike+ app for the iPhone 4.There's no longer any need for a sensor in your sports footwear, but you'll need an Apple handset with GPS functioning, with the new features specifically designed for handsets running iOS 4.According to TechRadar, new features on the app include a colour-coded pace tracker that shows how fast you were running over your route (working in conjunction with Google Maps) and a 'Challenge Me' function that allows you to challenge previous personal bests in distance or speed. Do that and you'll get a gold medal and a cheer. Not a real gold medal sadly, but the cheer is real enough.It also adds something else significant - a price tag. No free app here, you'll need to spend £1.19 to get it. Then again, what's that? A fraction of the price of a decent pair of running shoes, that's what. Nothing if you're serious about sport.