6 Tech Startups With a Fun Spin on Fitness Tech companies are taking the tedium out of training. Here are a few of our favorite digital fitness options.

The zombies are gaining on me. The wailing of the undead crescendos, then subsides as I put on a burst of speed that sends me out of the parking lot and onto the street. This time, I've escaped intact, but I likely haven't escaped judgment from the (living) people who can see me from their office windows, sprinting like a crazy person.

I'm Runner 5, about to clear my second mission in Zombies, Run!, an app from U.K.-based game-development agency Six to Start and writer Naomi Alderman, which has accomplished the improbable task of getting people to shell out money to go running. At $7.99 a pop (and with about 100,000 downloads sold in three months), that's no mean feat.