Workout

Warm-up (400)
400 choice

Set (600)
4 x 200 on 3:15 
...build

Set (1200)
3 rounds
100 easy on 2:15
200 moderate on 2:00
100 hard on 1:45

Set (800)
4 rounds
50 hard on 1:00
100 easy on 2:30
50 hard on 1:30

Cool-down (200)
EZ 200 choice