Fitness apps are becoming a hot new battleground. Facebook announced Thursday that it has purchased the company behind the popular fitness and health app with the rather generic name of Moves. The Facebook acquisition comes at the same time rumors have been circulating about Apple's interest in fitness, not to mention Nike's and others.

Deal terms were not made public, but The Wall Street Journal reported that the price was "nowhere near the size of other acquisitions [that Facebook] has made in recent months," which have been in the billions.

The Moves app tracks a user's daily exercise and health routines. On its corporate blog, ProtoGeo Oy, the company that developed the app, said Thursday that "the Moves experience will continue to operate as a standalone app, and there are no plans to change that or commingle data Relevant Products/Services with Facebook."

The company was founded at the beginning of last year in Helsinki, Finland, with the intent of creating an all-day activity diary for smartphones. Moves was launched in January of last year, and, to date, 4 million copies of the free app have been downloaded for iPhones and Android phones.

'Multi-App Strategy' Moves automatically monitors and tracks a user's physical activity, including walking, jogging, and bike riding. It also provides a map to show where the user has been. It has an unusually large number of activities it can track and detect, such as riding on public transportation, and it can interface with other apps. The app employs sensors used in many smartphones.

For its part, Facebook said in a statement that the acquisition was part of its "multi-app strategy," and key members of the Moves team, including founders Sampo Karjalainen, Aapo Kyrola and Zsolt Szasz, will move from Helsinki to join Facebook at its headquarters in Menlo Park, California.

Facebook is on a tear to add capabilities. Earlier this week, it announced FB Newswire, designed to make it easier for journalists and newsrooms to find and embed content from Facebook for their stories. While at the end of March, it announced an agreement to acquire Oculus VR, the company that produces the Oculus Rift virtual Relevant Products/Services reality headset.

More Data, Less Privacy?

A key question is the strategy behind all these Facebook acquisitions. Facebook Mark Zuckerberg has told analysts that the company's long-term goal is to feed the "full ecosystem" of how people share with other people.

Apps that track activities like exercise and local travel could be shared with other people, or posted on the site when the user has some proud sharing to do. But the data could also become grist for advertisers to determine who you are and what you do.

Even though the company behind Moves said its data will not "commingle" with Facebook, that could only mean it won't be diluted or integrated into the Likes and the Timeline.

It could still become part of the total Facebook data store, which means it will likely become available to advertisers. Which also means that it may well become another sore spot between users expecting privacy and Facebook's intention to provide advertisers with information about its members.