Race-Pace Swim Threshold Sets: 60-Minute Pool Session

Session Overview

This 60-minute pool session targets your swim threshold — the pace you can sustain at the upper limit of aerobic effort. By repeatedly hitting this intensity in a structured format, you train your body to clear lactate more efficiently and hold a faster pace for longer. It is the most direct route to improving your race-pace swim performance ahead of the spring race season.

What You’ll Need

• 25m or 50m swimming pool
• Swim cap and goggles
• Waterproof watch or poolside clock for interval timing
• Pull buoy (optional, for CSS reference sets)
• Knowledge of your Critical Swim Speed (CSS) — calculated from a recent CSS test

Warm-Up (12 minutes)

Start with 400m easy freestyle, broken into 100m segments at increasing effort. Follow with 4 x 50m as 25m drill plus 25m freestyle, focusing on catch and pull technique. End the warm-up with 4 x 25m build from 50% to 80% effort to prime your system for threshold work without fatiguing it before the main set.

Main Set

All main set efforts are performed at or slightly faster than your CSS pace. CSS is typically 3-5 seconds per 100m faster than a comfortable aerobic pace. If you do not know your CSS, aim for an effort that feels like 7-8 out of 10 — hard but sustainable for the full duration of each effort.

• Block 1: 4 x 200m at CSS pace, 30 seconds rest between each. Focus on consistent pacing across all four reps — the fourth should feel the same effort level as the first.
• Block 2: 6 x 100m at CSS pace minus 2 seconds per 100m (slightly faster than CSS), 20 seconds rest. Push the pace but maintain technique throughout.
• Block 3: 4 x 50m at the fastest sustainable pace you can maintain across all four reps, 15 seconds rest. These are not maximal sprints — hold consistent, controlled speed.

Cool-Down (8 minutes)

Swim 200m easy backstroke or relaxed freestyle to flush lactate from your working muscles. Add 4 x 25m sculling or fingertip drag drill to reinforce hand position and feel for the water before finishing. End with 100m at a comfortable pace, focusing on long, relaxed strokes and full exhalation underwater.

Coaching Notes

• If you slow significantly in the last Block 1 rep, reduce target pace by 2-3 seconds per 100m and rebuild consistency before pushing the pace again.
• Avoid going out too hard on the first intervals — consistent effort across all reps is more valuable than fast-then-slow oscillation.
• Scale down: Increase rest intervals to 40 seconds between the 200m efforts if the session feels too demanding at first.
• Target heart rate: Zone 4, approximately 80-90% of maximum heart rate, for all main set efforts.