Pasadena, California-based Stir, maker of the Stir Kinetic Desk, has announced integration with Fitbit's devices that have display screens -- the Fitbit Flex, Fitbit One and Fitbit Zip. Stir retails for $3,890.

The desk moves up and down as it learns from the user's behavior. Users can command the desk to move by tapping on a touchscreen sensor in the corner of the desk. Throughout the day, Stir might also slightly sway up and down while the user is working to remind users to move around.

Stir has always counted calories that the user burns while standing up and working, which it displays on the desk's touchscreen. It will now also integrate this data with Fitbit. Stir sends logs to Fitbit that show the user's time spent standing and extra calories burned during this time.

“Our goal is to increase movement, productivity, health, and inspiration at work by leveraging cutting-edge health tracking software and devices,” Stir CEO JP Labrosse, who was also part of the original iPod team at Apple, said in a statement. “Market-leader Fitbit has been a pioneer in enabling users to quantify their health, with a diverse product family that helps people reach their fitness goals by motivating them to move more, and this integration has been part of our roadmap since day one.”

Integrating with other devices is one of the new ways activity tracker companies are differentiating themselves in the increasingly crowded space.

For instance, in May, Jawbone partnered with Automatic, a smart driving tool that connects to a car’s computer through a small device, called the Link, and tracks driving stats for abrupt breaking, speeding, and rapid acceleration. Users who have Automatic, which costs $99.95, as well as a Jawbone UP fitness tracker, can now integrate their driving data into the Jawbone app so that it appears alongside their physical activity log.

If users miss their target step count for the day, the app might suggest that it was because they drove more than was necessary that day. Users will also be able to tap on a “drive” to view the number of steps they could have walked instead. Those who use the Jawbone app to track mood and diet can also compare this data to the time they spent in their car and the routes they took that day to correlate potential moments of road rage.