We're all so busy these days that workout programs which promise great results in only 25 minutes sound awesome. But do they work? Just how long do you have to work out to make a noticeable difference anyway?

The answer is: Yes, these quick workouts can work, and probably will if you go regularly. Depending on your body type and how fit you are, you can burn between 164 and 522 calories in 30 minutes. The catch is this: Express workouts typically work best on people who aren't fit. Once your fitness level improves, you'll have to take it up a notch, and might even need to start working out longer.

What do you think of express workouts?