Al Roker of “The Today Show,” Jimmy Kimmel of “Jimmy Kimmel Live,” and John Grisham (author of “The Reckoning” and at least 25 other books), swear by their treadmill desks. And they’re not alone.

Industry insiders estimate 400,000 to 600,000 treadmill desks were bought or constructed in the U.S. between 2007 and 2015. And that's not counting the increasingly popular pedaling workstations, at which some say it's easier to work.

A review of studies on cycling and treadmill workstations compared to standing desks — which was published in Occupational & Environmental Medicine — found that active workstations boost heart rate, alertness, and energy expenditure, and lower blood pressure during the working day.

Treadmill stations were associated with lower stress scores; cycling stations improved the speed of simple processing task.

The drawbacks? It can be hard to work on a computer while walking on a treadmill or cycling energetically.

Wondering about energy expenditure? A slow treadmill walk (if you weigh 155) uses 211 calories/hour. If you were burning an extra 500-plus calories, five days a week, you could lose a lot of weight.

Quick tip: If you have a standing desk instead of an active workspace, make sure you adjust its height and sit intermittently.

A study from Mount Sinai Medical School in NYC found that participants who used an adjustable workstation (not a static one) had less upper back, shoulder, and neck discomfort, and 65 percent reported increased productivity.