Warmup: 

10 minute build from DarkHorse Rowing (2144 meters)

Workout:
2 Rounds 
12 Calorie Echo Bike (26 & 26 seconds)
Rest 1:30 
Then
3 Rounds
15 Calorie Echo Bike (38, 46 & 53 seconds 🥵)
Rest 2:30
Then
12 Calorie Echo Bike (34 and 33 seconds)
Rest 1:30

We program bike sprints for two primary reasons:
1) High Output. You have an upper end output if you want to be able to keep up when an event or test does not afford you the ability to pace it. 
2) Recovery. If you're completely trashed after a couple of max effort bouts, that should indicate to you that both extremes of your fitness need work. Max output, plus the long-slow aerobic work which trains your body to flush waste and recovery between efforts.