Cross training is mentioned in every "run your best marathon ever" article, and is something I've been historically bad at working into my training. There is no mention of XT in HB, but I want to gain every advantage I can, so I'm making room for swimming and strength conditioning, primarily core workouts. The recovery run days seem most logical: Mondays will be a gym day, Fridays a swim day.
I went to the pool at lunch today for a 30 minute workout. I split the time into six 5 minute intervals and tried to swim 150 yards during each period with some rest at the end. 150 yards during int1 went too quickly, leaving me 75 seconds of rest, so I swam 175 yards for int2 and int3. But I started getting tired and slowed down so much that I only had 7 seconds of rest before int4. Int4 and int5 were cut down to 150 yards because of fatigue. But as I was swimming int6, I realized 150 yards would leave me at 950 yards for the workout. I swam an extra 47 seconds in order to get to an even 1000 yards for the day.
30:47 minutes, 1000 yards. I have no idea how those Olympians swim 10,000 meters!