Try this simple cardio workout the next time you need to burn some major calories. Pick three different machines, and go for 20 minutes on each. You could try incline treadmill walking, elliptical work and then finish with the bike.
20 minute treadmill + 20 minute elliptical + 20 minute bike = CALORIES
Using three different machines will train different energy systems , different movement patterns, prevent boredom and keep calorie burning high. Speaking of boredom, did you know that most of our cardio is compatible with your ipod or iphone? Plug it in and not only will it charge your device, but your play list will show up on the screen.
http://www.livestrong.com/article/112476-cardio-circuit-workouts/