Workout

Warm-up (1200)
6 x 50 on 1:00
8 x 50 on :50
10 x 50 on :45

Set (500)
6 x 50 @ 400 race pace 
...rest: 20 sec
200 easy

Set (500)
6 x 50 @ 200 race pace 
...rest: 20 sec
200 IM Drill

Set (300)
6 x 50 @ 100 race pace 
...rest: 20 sec

Cool down (300)
2 x 150 choice 
...rest: 30 sec