Workout

Warm Up  
Swim 400 choice

Set (2 rounds)
100 kick/50 free
50 kick/100 free
...rest 10 sec.

Main Set
2 x 300 on 5:00 (1:40 base)/HARD 400 on 6:00 (1:30 base)
2 x 200 on 3:20/HARD 300 on 4:30
2 x 100 on 1:40/HARD 200 on 3:00

--first two swims of every round are moderate. 
--the focus is on the longer swim in each round. 

Warm Down  
6 x 50 on 1:00
odds- 25 kick/25 fr
evens- build down