The Science of Periodisation
If you've ever wondered why elite triathletes seem to peak perfectly on race day while others fade, the answer often lies in periodisation—the systematic division of training into distinct phases, each with a specific purpose.
As a coach with 40+ years in the sport, I've seen countless athletes transform their racing by simply organising their training more intelligently. Let me show you exactly how a 16-week plan breaks down.
Why 16 Weeks?
Sixteen weeks is the sweet spot for most triathletes targeting Olympic or 70.3 distances. It provides:
- Enough time to build meaningful fitness
- Sufficient weeks for proper periodisation
- Room for one solid recovery block
- A manageable commitment window
For sprint distance, 8-12 weeks often suffices. For Ironman, you'll want 20-24 weeks minimum.
The Four Phases Explained
Phase 1: Base (Weeks 1-6)
The Purpose: Build your aerobic engine and movement efficiency
Think of base phase as laying the foundation of a house. Skip it, and everything built on top becomes unstable.
What Base Training Looks Like:
- Intensity: 80-90% of training at Zone 2 (conversational pace)
- Volume: Gradually increasing—start at 70% of your peak planned volume
- Focus Areas:
- Swim technique drills (catch, pull, rotation)
- Cycling cadence work (90-95 RPM comfort)
- Running form and easy aerobic miles
- Strength training 2-3x per week
Sample Base Week (Week 4 of 6):
| Day | Session | |-----|----------| | Mon | Rest or yoga | | Tue | Swim: 2,000m technique focus | | Wed | Bike: 60min easy + 6x30sec high cadence | | Thu | Run: 45min easy with 4x20sec strides | | Fri | Swim: 1,500m easy + drills | | Sat | Bike: 2hr easy endurance | | Sun | Run: 75min easy, conversational pace |
Common Base Phase Mistakes:
- Going too hard (if you can't hold a conversation, slow down)
- Skipping strength work
- Neglecting swim technique for "just getting metres in"
Phase 2: Build (Weeks 7-12)
The Purpose: Develop race-specific fitness and introduce intensity
Now that you have an aerobic foundation, it's time to build the walls and structure. This is where training gets more specific to your race demands.
What Build Training Looks Like:
- Intensity: 70-80% easy, 20-30% moderate-to-hard
- Volume: Peaks during this phase
- Focus Areas:
- Threshold intervals (bike and run)
- Race-pace swimming
- Brick workouts (bike-to-run transitions)
- Nutrition practice during long sessions
Key Workouts in Build Phase:
Threshold Bike: 20min warm-up → 2x20min at threshold (RPE 7-8) with 5min recovery → 10min cool-down
Tempo Run: 15min easy → 25min at half-marathon pace → 10min easy
Brick Session: 90min bike (last 20min at race pace) → immediate transition → 20min run at race pace
Sample Build Week (Week 9 of 12):
| Day | Session | |-----|----------| | Mon | Rest or easy swim 1,500m | | Tue | Run: 50min with 4x5min at threshold | | Wed | Bike: 75min with 2x15min tempo | | Thu | Swim: 2,500m with race-pace set | | Fri | Run: 30min easy | | Sat | Brick: 2.5hr bike + 30min run | | Sun | Swim: 2,000m easy + Run: 60min easy |
Recovery Week (Week 10): After 3 weeks of building, drop volume by 30-40% while maintaining some intensity. This allows adaptation and prevents burnout.
Phase 3: Peak (Weeks 13-14)
The Purpose: Sharpen race fitness and simulate race conditions
The house is built—now we're adding the finishing touches. Peak phase is about quality over quantity.
What Peak Training Looks Like:
- Intensity: Highest quality sessions of the plan
- Volume: Begins tapering (80-90% of build volume)
- Focus Areas:
- Race simulation workouts
- Pacing strategy practice
- Nutrition and hydration finalisation
- Mental rehearsal
Key Peak Phase Workouts:
Race Simulation Brick: Complete a "mini race"—half your race distances at race pace with full nutrition strategy.
Sharpening Intervals: Short, fast efforts to maintain top-end fitness:
- Swim: 8x100m at race pace with 15sec rest
- Bike: 5x3min at 105% FTP with 3min recovery
- Run: 6x800m at 5K pace with 90sec jog
Sample Peak Week:
| Day | Session | |-----|----------| | Mon | Rest | | Tue | Swim: 2,000m race-pace set | | Wed | Bike: 60min with 3x5min above threshold | | Thu | Run: 40min with 5x3min at race pace | | Fri | Swim: 1,500m easy | | Sat | Race simulation brick (50% race distance) | | Sun | Easy 45min run + stretch |
Phase 4: Taper (Weeks 15-16)
The Purpose: Arrive at race day fresh, fit, and ready to perform
This is where the magic happens—and where many athletes sabotage themselves. The taper allows accumulated fatigue to dissipate while fitness remains.
What Taper Looks Like:
- Volume: Drops 40-60% from peak
- Intensity: Maintain some race-pace efforts (keeps you sharp)
- Focus Areas:
- Extra sleep (8-9 hours if possible)
- Nutrition optimisation
- Equipment checks
- Mental preparation
- Trust the process!
Sample Taper Week (Race Week):
| Day | Session | |-----|----------| | Mon | Rest or 20min easy swim | | Tue | Bike: 30min easy with 3x1min race pace | | Wed | Run: 20min easy with 4x30sec strides | | Thu | Swim: 1,000m easy, some race-pace | | Fri | Complete rest or 15min walk | | Sat | 15min easy bike spin, check equipment | | Sun | RACE DAY 🏊♂️🚴♂️🏃♂️ |
Taper Truths:
- You WILL feel restless and anxious—this is normal
- You might feel sluggish initially—this passes
- You haven't "lost fitness"—it takes 2-3 weeks of no training for that
- Trust the work you've done
Visualising the 16-Week Structure
| Phase | Weeks | Volume | Intensity | Primary Focus | |-------|-------|--------|-----------|---------------| | Base | 1-6 | Building | Low | Aerobic foundation, technique | | Build | 7-12 | Peak | Moderate-High | Race-specific fitness | | Peak | 13-14 | Reducing | High quality | Sharpening, simulation | | Taper | 15-16 | Low | Maintained | Recovery, freshness |
How to Know It's Working
Signs your periodisation is on track:
✅ Gradual improvement in key workouts
✅ Consistent energy levels (not chronically tired)
✅ Positive response to recovery weeks
✅ Race-pace efforts feeling more sustainable
✅ Good sleep and stable mood
Warning signs to adjust:
⚠️ Persistent fatigue lasting more than a week
⚠️ Declining performance in similar workouts
⚠️ Frequent illness or niggles
⚠️ Loss of motivation or dread about training
Adapting to Your Life
Remember: this framework is a guide, not a rigid prescription. Real life happens—work stress, family commitments, travel, illness. A good plan adapts.
If you miss a week: Don't try to "make it up." Simply continue from where you are.
If you're feeling fatigued: Take an extra rest day. One day off is better than three weeks with injury.
If life gets chaotic: Prioritise quality over quantity. Three good sessions beat six mediocre ones.
Take the Next Step
Understanding periodisation is one thing—implementing it effectively is another. If you want a structured plan that takes the guesswork out, check out my Training Plans designed with proper periodisation built in.
Or, if you want personalised guidance and accountability, explore 1-on-1 Coaching where I'll design and adapt your training to your specific goals and life.
Questions about structuring your training? Reach out—I love helping athletes train smarter.