Apple and Nike's "Nike + iPod" system enable iPod nano users to track their workout using a sensor embedded in their shoe that records information stored on the iPod - great if you're running, jogging or walking. Now that system is being extended to work with gym equipment, as well.

On Tuesday Nike and Apple announced they are working with major gym equipment manufacturers including Life Fitness, Precor, Star Trac and Technogym to make their equipment Nike + iPod compatible. Participating gyms will include 24 Hour Fitness and Virgin Active Health Clubs.

Now users and their personal trainers will be able to track workouts on cardio equipment by plugging in their iPods at the start of the workout. Just like with running, the iPod will upload the data to Nikeplus.com. The workout data will be converted to "CardioMiles" so you can see how much you've used the cardio equipment and can set goals, participate in challenges with other users and more.