Skip to content

Swimming 2026: Plan to 4km

Current State (January)

  • Volume: ~1,500m per session
  • Pace: ~2:25-2:30/100m
  • CSS: not measured
  • Pool: 20m

Training Phases

Phase 1: Base (January — February)

Goal: find CSS, build aerobic base, develop technique

Week 1: CSS Test - Warmup 400m - 400m max effort → record time - Rest 10-15 min - 200m max effort → record time - Cooldown 200m - Calculate CSS = 200 ÷ (T400 − T200)

Weekly Structure:

Day Workout Volume
Mon Technique: 200 warmup + 400 drill + 600 Z2 + 100 cooldown 1,300m
Wed Threshold: 200 warmup + 6×100 at CSS (rest 20s) + 200 Z2 + 100 cooldown 1,100m
Fri Long: 200 warmup + 800-1000 continuous Z2 + 100 cooldown 1,100-1,300m

Weekly Volume: 3,500-3,700m

Week-by-week Progression: - Wk 1-3: volume ↑ 10% per week - Wk 4: deload −30% - Wk 5-7: volume ↑ 10% - Wk 8: deload + CSS re-test

Phase 1 Success Markers: - [ ] CSS determined - [ ] 1000m continuous in Z2 without HR drift - [ ] Consistent stroke count per length (±1)


Phase 2: Aerobic Development (March — April)

Goal: increase volume, extend continuous intervals

Weekly Structure:

Day Workout Volume
Mon Technique: 300 warmup + 500 drill + 800 Z2 + 200 cooldown 1,800m
Wed Threshold: 300 warmup + 4×200 at CSS (rest 30s) + 300 Z2 + 200 cooldown 1,600m
Fri Long: 300 warmup + 1200-1500 continuous Z2 + 200 cooldown 1,700-2,000m

Weekly Volume: 5,100-5,400m → by end of phase 6,000m

Progression: - Wk 1-3: build up - Wk 4: deload - Wk 5-7: build up - Wk 8: deload + 1500m continuous test

Phase 2 Success Markers: - [ ] CSS improved by 3-5 sec/100m - [ ] 1500m continuous in Z2 - [ ] 30 minutes of swimming without stopping - [ ] HR drift over 1000m < 8 bpm


Phase 3: Threshold Development (May — June)

Goal: improve CSS, sustain threshold pace longer

Weekly Structure:

Day Workout Volume
Mon Technique: 400 warmup + 400 drill + 1000 Z2 + 200 cooldown 2,000m
Wed Threshold: 400 warmup + 3×400 at CSS (rest 45s) + 400 Z2 + 200 cooldown 2,200m
Fri Long: 400 warmup + 1800-2000 continuous Z2 + 200 cooldown 2,400-2,600m

Weekly Volume: 6,600-6,800m → by end of phase 7,500m

Key Workouts: - Threshold: 3×400 → 2×600 → 3×500 → 2×800 - Long: build up to 2000m continuous

Phase 3 Success Markers: - [ ] CSS improved by another 3-5 sec (total −6-10 sec from January) - [ ] 2000m continuous in Z2 - [ ] Hold CSS over 1200m with even splits - [ ] Negative split on 1000m test


Phase 4: Endurance (July — August)

Goal: peak volume, long continuous swims

Weekly Structure:

Day Workout Volume
Mon Mixed: 400 warmup + 300 drill + 1500 Z2 (varying pace) + 200 cooldown 2,400m
Wed Threshold: 400 warmup + 2×800 at CSS (rest 60s) + 400 Z2 + 200 cooldown 2,600m
Fri Long: 400 warmup + 2500-3000 continuous Z2 + 200 cooldown 3,100-3,600m

Weekly Volume: 8,100-8,600m → peak 9,000-10,000m

Key Test (end of August): - 3000m continuous, record time and HR per segment

Phase 4 Success Markers: - [ ] 3000m continuous - [ ] HR stable after minute 20 - [ ] Pace over 3km close to CSS + 5-10 sec - [ ] 45+ minutes of continuous swimming


Phase 5: Race-Specific Preparation (September — October)

Goal: taper toward 4km, test

Weekly Structure (September):

Day Workout Volume
Mon Technique + Z2: 400 warmup + 400 drill + 1200 Z2 + 200 cooldown 2,200m
Wed Tempo: 400 warmup + 1500 at CSS (continuous) + 400 Z2 + 200 cooldown 2,500m
Fri Long: 400 warmup + 3000-3500 Z2 + 200 cooldown 3,600-4,100m

October — 4km Test: - Week 1-2: maintenance volume - Week 3: deload −40% - Week 4: 4000m TEST

4km Test Protocol: 1. Warmup 400m (outside of test) 2. Start, record time every 400m 3. Goal: even splits, negative split on last km 4. Cooldown 200m

Success Markers: - [ ] 4000m continuous ✓ - [ ] Time < 1:40:00 (pace < 2:30/100m) - [ ] Last km not slower than the first


Phase 6: Maintenance (November — December)

Goal: maintain fitness, focus on Boka Half Marathon

Volume: 5,000-6,000m per week (−40% from peak)

Structure: - 2-3 sessions per week - No long swims - Technique + Z2, occasional short threshold


Tests and When to Do Them

Test Frequency Purpose
CSS (400+200) Every 8 weeks Track threshold improvement
20 min continuous Monthly How many meters at Z2
HR drift 1000m Monthly Aerobic efficiency
Strokes per length Every session Technique under fatigue

How to Know Things Are on Track

Green Flags (all good): - CSS improves by 2-3 sec every 2 months - HR at same pace decreases - Stroke count stays stable - Negative splits happen naturally

Red Flags (something is off): - CSS unchanged for 2+ months - HR rises at same workloads - Constant fatigue - Stroke count increases toward end of session

If Red Flags Appear: 1. More rest (deload week) 2. Check sleep, nutrition 3. Lower intensity, keep volume 4. More Z1-Z2, less threshold

Zone Calculation (fill in after CSS test)

CSS: ______ /100m

Zone Pace Example (if CSS = 2:10)
Z1 CSS + 20s 2:30/100m
Z2 CSS + 10s 2:20/100m
Z3 CSS 2:10/100m
Z4 CSS − 10s 2:00/100m