iTunes and Nike+ present the running community with a little extra motivation from the sport's hottest star Kara Goucher.

KARA GOUCHER'S ENDURANCE BOOST

Want to achieve the combination of speed and endurance that powers elite athletes? Join Kara Goucher, one of America's premier middle- and long-distance runners, for a 40-minute workout designed to strengthen your cardio and improve your speed. Kara will coach you through a warm-up and four sets of high-speed intervals-the kind of training technique top competitors swear by.

The distance will melt away as you listen to an energizing, set of music featuring artists like the Black Eyd Peas, Beck , the Fratellis, One Republic, and Jimmy Eat World. Power through the speed intervals and tak full advantage of the regular recovery periods with standout tracks like Beck's "Timebomb" and the sassy old-school bounce of Kenna's "Say Goodby to Love". You'll warm up and cool down at a comfortable pace, and blaze through a calorie combusting challenge with help from one of the USA's true track and field heroines.

When you're finished with your workout, check out Kara's bonus interview in which she gives the lowdown about life with her husband, fellow elite runner Adam Goucher, her triumphant comeback from career threatening injury and what it's like to run in something called a plastic sweatsuit. Enjoy the workout (pastic sweatsuit optional).