The Last Lung Buster.

...at least for a while.  I did probably my favorite swim workout today.  After warmup:
2x50 fast
100 (breadth every 6)
2x50 fast
200 (breadth every 5)
2x50 fast
300 (breadth every 4)
100 cooldown.
The 2x50s get you (and keep you) breathing hard.  I almost feel as though I'll pass-out during the 100; then again on the 200.  The 300 is easier, but still hard - kind of winding down.  I'm not sure if this help lung capacity or not - but it's hard to imagine a workout testing the lungs like this one.  Did the hills Tuesday, and an easier swim workout Monday - as well as strength on Sunday.