If you’re a dedicated runner, you’re probably familiar with interval workouts- a time-honored technique used to build strength, speed and endurance. Like a traditional interval run, the Spontaneous Speed workout consists of a warm-up period followed by stretches of fast-paced running. But here’s the twist- in this run, you don’t know what’s coming or when.

Serena will coach you through a series of high-intensity speed bursts while keeping you sharp with her trademark wit and style - she’s one coach you won’t want to disappoint. Plus, as you tackle this dynamic solo contest, a hand-picked set of some of Serena’s favorite music helps you power through. From Mary J. Blige’s hit “Just Fine” to the harmonic flow of Timbaland & OneRepublic’s “Apologize,” the playlist is as exciting and ever-shifting as the workout itself.