Found this part rather interesting....
I usually do four pretty heavy workouts a week in the pool. I discovered that instead of an aerobic workout, which would be grinding out 4,000 or 5,000 meters, I'm better off doing a much faster workout -- what they call "anaerobic" work. This is really a race-pace type workout, where you're doing maybe 10 , swimming as hard as you can, on a set time on the clock