Pedal at an easy pace with a light resistance (0-25%) for 5 minutes.
After 5 minutes are up, pedal as fast as you can at the same resistance for 10 seconds. This is the beginning of the intensity period.
Increase the resistance to the highest possible level (or if you need to scale it back, to 75%) and continue pedaling as fast as you can for 20 seconds at the increased resistance.
Decrease the resistance back to the previous light resistance and pedal for 90 seconds at an easy pace again. This is the active rest period.
After 90 seconds, begin the intensity period again with 10 seconds of fast pedaling followed by 20 seconds of intense pedaling with the highest resistance. Continue repeating this protocol until 15 minutes are up.
-Nick M., University of Tennesee Health Science Center