This workout can be performed on an exercise bike, a bike outdoors, on an elliptical, on a treadmill, or running outdoors.
Let's Get Some Definitions Straight.
The warm-up should be easy enough that you could comfortably talk during it. Exertion scale: about 4 out of 10.
The sprint should be hard enough that you feel like it's gonna kill you. Exertion scale: about 9 out of 10.
The active recovery should be slow enough that you can regain your breath before the next sprint. Exertion scale: about 3 out of 10.
min. 0:00 - 5:00 warm-up
min. 5:00 - 5:40 sprint
min. 5:40 - 7:00 active recovery
min. 7:00 - 7:40 sprint
min. 7:40 - 9:00 active recovery
min. 9:00 - 9:30 sprint
min. 9:30 - 11:00 active recovery
min. 11:00 - 11:30 sprint
min. 11:30 - 13:00 active recovery
min. 13:00 - 13:20 sprint
min. 13:20 - 15:00 active recovery
min. 15:00 - 15:20 sprint
min. 15:20 - 17:00 active recovery
min. 17:00 - 20:00 cooldown
This workout will boost your endurance and provide a fat-burning interval stimulus. It's also low-impact in case you're dealing with creaky joints or you just need a day that's gentler on impact. Because the intervals get shorter as the workout progresses, you will be motivated to push hard.