A treadmill desk is a desk that doesn't have a chair, but instead has a treadmill in front of it. The theory is that you stand up and walk while you work or play on your computer, getting exercise while going digital. When I first heard this idea, I thought the idea was completely insane. But the more I hear about it, the more it make sense to me, and I think I'll give it a try.The theory is that you walk along at 1 mph while working -- fast enough to get your blood moving.

Because 1 mph doesn't speed up the metabolism a whole lot, the treadmill desk wouldn't be a substitute for a good workout -- doctors currently recommend at least a half hour of moderate cardio exercise, such as walking, swimming, or biking, on most days of the week.

But doctors also say that the more exercise you get, the healthier you'll be. And that's where the treadmill desk might come in -- adding a few miles a day to your walking sounds all good.

Rich W. Klein has been using a treadmill desk for several weeks now. He put a bar table on a couple of cinderblocks and positioned it at the front of the treadmill. He has pictures on his blog. He writes:

I've been using the desk for about 3 weeks now and it is working wonderfully. I have a routine where I come down to my office and work on my regular desk while I have breakfast and catch up on my e-mail. I then move the laptop over to the treadmill and work there for two hours. I walk for two hours at one mile an hour so I walk two miles and burn about 470 calories. I've actually gotten pretty good at working while I walk. I almost think I work faster. Once the two hours are up its back to my regular desk for the rest of the day. Since I've started walking and eating better, I've dropped 10 pounds and I am continuing to lose. I think after another week or two I'm going to bump up the time on the treadmill some more although I don't think I necessarily have to.

If a table balanced on cinderblocks is a little low-tech for you, you can buy a treadmill desk from Steelcase for $6,000. The Treadmill Desk Blog has the details on that and more.

Maybe in 10 years, enlightened companies will offer all their employees treadmill desks as an option for their offices and cubicles. We'll all look like a bunch of idiots, walking while we work -- but we'll be healthy idiots.

Steelcase has a promotional video on its treadmill desk:

And Good Morning, America did a segment:

One treadmill desk advocate on GMA says she can do everything on her treadmill desk that she can do on a standard desk. The video shows her talking on the phone while walking; she sounds normal.

Dr. Richard Levine, who advocates the treadmill desk, said that simply standing rather than sitting is healthier for you, burning an additional 20 calories per hour. Ernest Hemingway used a standing desk, as did Winston Churchill, Virginia Woolf, and former U.S. Secretary of Defense Donald Rumsfeld.

How do you keep fit while working long days? Let us know.