Remember when pricey chairs like the Aeron were the must-have office items? Now, the chair itself is positively passé.

The latest status symbol for the office doesn't use a chair at all. It's the standing desk, and it's becoming a hot item in Silicon Valley. At Google (GOOG) and Facebook, workers have replaced the traditional setup with higher desks that you can use while standing or perched on a stool, The Wall Street Journal reports.

Even better? The treadmill desk. Facebook has set up some treadmill stations where people can walk while working on the computer.

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These desks are becoming trendy because employees worry about the health problems that come with sitting all day, the Journal reports. Studies show that people who sit for more than six hours a day are more likely to die prematurely.

"I don't get the 3 o'clock slump anymore," one Facebook employee with a standing desk told the Journal. "I feel active all day long."

Want to try a treadmill desk for yourself? Amazon sells them for $480 -- but you have to buy the treadmill separately.