Swim Efficiency Circuit: SWOLF Test and CSS Speed Blocks

Session Overview

This 45-minute pool session measures your stroke efficiency using the SWOLF score, then immediately trains you to swim faster at critical swim speed (CSS). It’s the ideal session to benchmark your swim efficiency and build speed in the same workout — available to all ability levels.

What You’ll Need

• 25m or 50m pool
• Waterproof watch with stroke count function (or manually count strokes)
• Pull buoy (optional, for CSS set variation)
• Pace clock or lap timer

Warm-Up (10 minutes)

400m easy: 100m freestyle, 100m choice of drill (fingertip drag or catch-up), 100m freestyle, 100m easy backstroke. This primes your stroke without fatiguing you before the SWOLF test.

Main Set

Part A — SWOLF Test (15 minutes): Swim 3 × 50m at moderate effort (RPE 6), recording your time and stroke count for each length. Add time (seconds) + strokes per length = your SWOLF score. Average your three scores. A lower SWOLF = better efficiency. Record this as your baseline.

• 50m rep 1: Count strokes + time — record both
• 50m rep 2: Try to reduce stroke count by 1 without slowing down
• 50m rep 3: Try to reduce time by 1 second without adding extra strokes

Part B — CSS Speed Blocks (15 minutes): 8 × 75m at CSS pace (your critical swim speed — roughly your 400m TT pace per 100m), with 20 seconds rest between each. Aim for consistent splits across all 8 reps.

Cool-Down (5 minutes)

200m easy choice of stroke. Check your SWOLF score from the CSS set if your watch auto-records it — you should see efficiency hold or improve even at race-pace effort.

Coaching Notes

• A good SWOLF for club-level triathletes is 40–55 for a 25m pool; elite is below 35
• Focus on long, clean strokes in the SWOLF test — glide before catch, full extension
• Don’t know your CSS pace? Swim a 400m time trial and a 200m TT then calculate using the CSS formula
• RPE for CSS set should be 7–8; if you’re going 9, you’re swimming too fast