Broken 400s

About 1,800 m, 45 minutes. Lets you swim faster than your straight 400 pace for the full distance, with brief pauses to make it possible. Warm-up: 400 easy, including a few fast 25s. Main: 3 x 400, each broken into 4 x 100 with 10 s rest at every wall stop. Take 1 minute easy between 400s. Cool-down: 200 easy. Add up the four swim times of each 400, leaving out the rests, and try to beat your best continuous 400. That total is the number to write on the card. As fitness builds, cut the rest to 5 s, then break the 400 into two 200s instead.