The companies said Tuesday they are working with several gym equipment makers and the health clubs 24-Hour Fitness and Virgin Athletic Health Clubs to allow members to plug their iPod Nano into cardio equipment.

The Nanos would track workouts, set goals and upload the information to a Nike website.

The new technology is expected to hit more than 500 gyms worldwide this summer.

It's another major partnership for Nike and Apple, which created Nike+ technology more than a year ago. The wireless system allows some Nike running shoes embedded with a sensor to communicate with Apple's iPod Nano.

Apple and Nike said shifting to the gym was the next natural step.

"People enjoy tracking themselves as a way to keep themselves motivated," said Trevor Edwards, Nike's vice president of global brand and category management. "They want to get credit."

It also builds on the surprise success of the online community that built up around the technology.

Nike would not disclose the number of members to its Nike+ site but has said previously that roughly 1,000 runners sign up daily. It has members in more than 160 countries, including some where the product isn't even sold.

In addition to tracking their progress, users can access other benefits such as buying specialty songs or joining in social network components, such as challenging other users to a workout goal.

"We've definitely struck on to something," Edwards said.

Apple and Nike wouldn't say what's next, but say there are plans to grow.