Here's one my triathlon coach gave us a couple of weeks ago, I thought
I'd share it. Maybe this should be cross posted to alt.masochism...
It's intended for use as the main set, after a couple hundred yards
easy warmup. Supposedly the goal is to build VO2Max, increase ability
to use full lung cpacity, and build "mental toughness". Not sure about
the first two, but it definitely tested #3 in my case.
Swim 1600 yards at a medium-strong pace. Broken up into 8 200s (no rest
in between). Each 200 is a breathing exercise, broken into 4 50s. The
first 50 you breathe every 3, second every 4, third every 5, fourth
every 6 strokes. If you normally breathe every two you can start at two
instead and go to 5. Repeat 8x without pausing.
I noticed that even though I was dying at the end during the 5s and
6es, the increased stroke rate put me in a faster "gear" and I ended up
negative splitting the 200s. It also made breathing every 4 or 5 seem
like a luxury. (I normally do every 3).
Have fun