Here's the thing: Of course, we're less active in the workplace. Most, not all, people sit in front of a computer for much of the day. We need a study to tell us the obvious?
We've known this for a long time. That's why there have been tips like this: Use the stairs, park far away from the office, get up during the day and move.
Here's the article in the New York Times.
Here's my prediction: Studies like this will be used to sell workstation treadmills.