Open Water Negative Split Build: 3×600m Progressive Swim

Session Overview

Three 600m efforts in open water, each faster than the last. Negative split swimming — getting progressively faster through a race — is one of the most effective race strategies for triathletes, but it must be practised. This session trains that discipline and teaches you to trust the process of holding back early and finishing strong.

What You’ll Need

• Open water access — lake, reservoir, or calm sea
• Wetsuit if water temperature is below 18°C
• Bright coloured swim cap (safety — be visible)
• Inflatable safety buoy (tow behind you — essential for solo open water swimming)
• GPS watch to pace each 600m effort accurately
• Swimming buddy or kayak support (strongly recommended)

Warm-Up (10 minutes)

400m easy swimming along the shoreline at RPE 3-4, practising sighting every 8-10 strokes. Include 4 × 25m pick-ups (increasing to threshold pace then backing off) to prime your stroke for the main set. Tread water for 1 minute before the first effort.

Main Set

Sight consistently throughout each effort — aim to swim a straight line rather than the fastest line. Use your GPS watch to check pace after each 200m section and consciously speed up in the second half of each 600m.

• 600m Effort 1: Comfortable Zone 2 pace (RPE 5) — note your split time on GPS
• 2 minutes recovery (tread water, catch your breath, check your watch)
• 600m Effort 2: Tempo pace (RPE 7) — aim to be 5-8% faster than Effort 1
• 2 minutes recovery
• 600m Effort 3: Race pace (RPE 8-9) — aim for 5-10% faster than Effort 1 and 2-4% faster than Effort 2

Cool-Down (5 minutes)

200m easy mixed strokes (backstroke, breaststroke, easy freestyle) back toward the entry point. Take time to float on your back for a minute — it’s a great way to decompress after the intensity of the main set and begin your parasympathetic recovery.

Coaching Notes

• The biggest mistake in open water racing is going out too hard — this session is training you NOT to do that
• Write your target splits on your wrist with a waterproof marker before the session so you can check them mid-effort
• Sighting every 8-10 strokes in open water is essential — lift your head just above the water surface, not high out of the water
• Easier version: reduce efforts to 400m each. Harder version: extend each effort to 800m and add a fourth repeat at max effort
• Never swim alone in open water — always use a safety buoy and swim with a partner or notify someone of your location and expected return time