I swam this workout (short course yards) this very morning and I loved it.
Warm Up Set:
(If you have a thing against breaststroke and butterfly, I would suggest alternating backstroke and freestyle on the 50s)
100 free pull buoy only 1:30
2x 50 freestyle 1) drill 2) swim :60
100 free pull buoy only 1:30
2x 50 breaststroke 1) drill 2) swim :60
100 free pull buoy only 1:30
2x 50 backstroke 1) drill 2) swim :60
100 free pull buoy only 1:30
2x 50 butterfly 1) drill 2) swim :60
Main Set:
This main set can be very easy or very very hard. Ultimately, it demands proper pace control. In basic terms it is 5x 500 descend. I see a lot of people starting sets at a brisk pace only to peter out by the end. There is a saying in swimming, "last one fast one" with the idea fitness is created by pushing your limits on the last one. BUT that does not mean you should ever sandbag (sandbaggers are much despised) which is why the intervals here are on the quick side. You should not take more than :10 secs rest at each distance.
1. 2x
250 @ 3:25 or :10 rest
→ get total swim time
2. 4x
125 @ 1:45
→ cumulative time
faster than #1
3. 5x
100 @ 1:25
→ cumulative time faster
than #2
4. 10x
50 :45
→ cumulative time
faster than #3
5. 500
@ 6:30
→
cumulative time faster than #4
200-300 cool down
(3900-4K)