I ran 15 minutes in Zone 2 around the track.
I swam 100 yards warm up @ 1.36 seconds per stroke; (16 X) 50 yards @ 1.34, 1.32, 1.30, 1.28, 1.26, 1.24, 1.22, 1.20, 1.20, 1.22, 1.24, 1.26, 1.28, 1.30, 1.32, 1.34 seconds per stroke; 100 yards cool down @ 1.36 seconds per stroke.
I maintained 18 - 20 strokes per length.
It's hard to put into words how the swim workout went; see the chart below. Overall, it's clear that I fatigue throughout the workout. My second repeats of 1.22 - 1.34 all took longer than the first repeats and there was a sharp positive slope throughout the repeats. And had it not been for some good repeats at 1.24, 1.22, 1.20 and 1.20 the best fit line would have had basically the same sharp positive slope. I don't know what to make of the huge jump from 1.20 to 1.22 seconds per stroke or of the fact that the time just kept climbing from there, other than I must have really been done after the second repeat at 1.20 seconds per stroke.
At least I stayed under one minute (and actually under 59 seconds) for all the repeats. I wonder what would have happened if I did more repeats at 1.34 seconds per stroke at the end (or more repeats at 1.20 seconds per stroke in the middle).