Friday

30:00 swim @ Z1

1000 yards (short course) - did 5 sets of 200 (75 free + 25 breast + 25 free + 25 breast + 25 free + 25 breast), beginning every 6:00 (about 0:60 rest between sets)

Yep, definitely feel an improvement aerobically!  Could have done this for another hour, and it was very easy to do sets of 200 instead of sets of 100 like I usually do.