Sprint 25s and 50s

About 1,500 m, 35 to 40 minutes. A short, sharp session for days when you want speed rather than mileage. Warm-up: 400 easy, finishing with 4 x 25 building to fast. Main: 3 rounds of 4 x 25 all-out with 30 s rest, then 100 easy. Follow with 4 x 50 fast with 1 minute rest. Cool-down: 300 easy, mixing strokes. The long rests are the point: every 25 should be as quick as the first, and if one drops off badly the rest was too short. Keep your stroke long instead of thrashing. Because it is low in distance, this one slots in well before work or the day after a long swim. Add a fourth round for 1,700 m.