PM - F500 - 3 x 20mins high intensity continuous training (HICT) with 5-10mins recovery between sets. First 20min set did step-ups...2nd set used spin bike at the highest possible resistance...last set went back to step ups. HICT is done to increase endurance properties of fast twitch muscle fibers. You don't see this training very often.
Here's a video describing HICT.