endurance-coach/reference/periodization.md

Periodization & Progressive Overload

Macrocycle Structure

Divide the training period into phases:

1. Base Phase (40-50% of available time)

• Build aerobic capacity
• Increase volume gradually (max 10% per week)
• Mostly Zone 2 (conversational pace)
• Focus on technique, especially in swimming

2. Build Phase (30-40% of available time)

• Introduce intensity (tempo, threshold work)
• Sport-specific workouts
• Race-simulation sessions (brick workouts for tri)
• Peak volume weeks occur here

3. Peak/Race-Specific Phase (10-15% of available time)

• Reduce volume, maintain intensity
• Race-pace work
• Course-specific preparation (hills, open water)

4. Taper (1-3 weeks depending on event)

• Significant volume reduction (40-60%)
• Maintain some intensity
• Focus on rest, nutrition, mental prep

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Microcycle Structure (Weekly)

Principles (more important than specific days)

1. Separate hard days - 48hr between quality sessions in the same sport
2. No same sport back-to-back - Spread swim/bike/run across the week (no swim Mon + swim Tue)
3. Respect long session recovery - Easy day after long rides/runs
4. Consistent weekly structure - Same sports on same days each week helps athletes plan
5. Include doubles strategically - AM/PM splits for time efficiency or brick practice

Sample Week Templates

Template A: Traditional (Mon rest)

Day	Session 1	Session 2
Mon	Rest	-
Tue	Swim (quality)	-
Wed	Bike (easy)	Strength
Thu	Run (quality)	-
Fri	Swim (easy)	-
Sat	Bike (long)	Run (brick, easy)
Sun	Run (long)	-

Template B: Weekend Warrior (busy weekdays)

Day	Session 1	Session 2
Mon	Rest	-
Tue	Swim (AM, 45min)	Run (PM, easy)
Wed	Bike (trainer, 60min)	-
Thu	Swim (AM, 45min)	Strength (PM)
Fri	Rest	-
Sat	Bike (long, outdoor)	-
Sun	Run (long)	Swim (easy, PM)

Template C: 70.3 Build Phase

Day	Session 1	Session 2
Mon	Easy swim or rest	-
Tue	Bike (sweet spot)	-
Wed	Run (tempo)	Strength
Thu	Swim (threshold)	-
Fri	Rest or easy spin	-
Sat	Bike (long)	Run (brick)
Sun	Run (long)	-

Avoid These Patterns

• ❌ Same sport on consecutive days (swim Mon + swim Tue, run Thu + run Fri)
• ❌ Quality run day after long ride (insufficient recovery)
• ❌ Two threshold sessions in same sport within 48hr
• ❌ Long sessions back-to-back without one being easy

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Progressive Overload

The 10% Rule: Increase weekly volume by no more than 10% per week—for athletes building new fitness.

Adjust Progression Based on Athletic Foundation

Foundation Level	Progression Rate	Rationale
True beginner	5-10% per week	Everything is new; high injury risk
Some experience (1-2 years)	10% per week	Standard progression
Strong foundation, returning	10-15% per week	Body remembers; rebuilding is faster
Recent high fitness	Maintain or small build	Already fit; focus on specificity

Example: An Ironman finisher who took 3 months off can progress faster than a beginner. Their muscles, tendons, and cardiovascular system have adapted before. Where a beginner might take 20 weeks to reach 10-hour training weeks, someone rebuilding might get there in 10-12 weeks.

However: Always validate with the athlete. Time off due to injury requires more caution than time off due to life circumstances.

3:1 or 4:1 Loading

• 3 weeks building load, 1 week recovery (reduce volume 30-40%)
• Or 2 weeks building, 1 week recovery for older/injury-prone athletes
• Athletes rebuilding can often handle 3:1; beginners may need 2:1

Long Session Progression

For a target marathon (42km), build the long run over 12-16 weeks:

Week 1:  16km
Week 2:  18km
Week 3:  20km
Week 4:  14km (recovery)
Week 5:  20km
Week 6:  22km
Week 7:  24km
Week 8:  16km (recovery)
...continue to 32-35km peak

Never increase the long session by more than 2-3km (running) or 15-20km (cycling) per week.

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Event-Specific Training Requirements

Full Ironman (140.6)

Minimum training time: 12-15 hours/week at peak Minimum build time: 24-30 weeks from solid base

Weekly structure at peak:

• Swim: 3x per week, 8-12km total
• Bike: 3x per week, 250-350km total, one ride of 150-180km
• Run: 3-4x per week, 50-70km total, one run of 28-32km

Key workouts:

• 5-6 hour bike followed by 30-60min run (brick)
• Long swim of 3500-4000m continuous
• Back-to-back long sessions on weekends

70.3 / Half Ironman

Minimum training time: 8-12 hours/week at peak Minimum build time: 16-20 weeks from solid base

Weekly structure at peak:

• Swim: 2-3x per week, 6-8km total
• Bike: 2-3x per week, 150-200km total, one ride of 80-100km
• Run: 3x per week, 35-50km total, one run of 18-22km

Marathon

Minimum training time: 6-10 hours/week at peak Minimum build time: 16-20 weeks

Weekly structure at peak:

• 5-6 running days
• 60-90km per week for experienced runners
• One long run (28-35km)
• One quality session (tempo or intervals)
• One medium-long run (18-22km)
• Remaining runs easy

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Physiological Adaptations: The "Why"

Why Easy Training Works (Zone 2)

Adaptation	Timeline	Mechanism
Increased mitochondrial density	4-8 weeks	More cellular powerhouses for aerobic energy
Capillarization	6-12 weeks	More blood vessels deliver oxygen to muscles
Improved fat oxidation	4-6 weeks	Shifts fuel use from glycogen to fat
Increased stroke volume	8-12 weeks	Heart pumps more blood per beat
Type I fiber development	Ongoing	Slow-twitch fibers become more efficient

Zone 2 is the foundation—never sacrifice it for more intensity.

Why Threshold Training Works (Zone 4)

Adaptation	Timeline	Mechanism
Lactate clearance	2-4 weeks	Muscles better at processing lactate
Raised lactate threshold	4-8 weeks	Sustain higher intensity before lactate accumulates
Improved muscle buffering	3-6 weeks	Tolerate higher lactate levels
Mental toughness	Immediate	Learn to sustain "comfortably hard"

Why VO2max Intervals Work (Zone 5b)

Adaptation	Timeline	Mechanism
Increased VO2max	4-8 weeks	Maximum oxygen uptake improves
Cardiac output	6-12 weeks	Heart pumps more blood per minute
Neuromuscular recruitment	2-4 weeks	Better coordination at high speeds

Use sparingly—1x/week max, requires 48-72hr recovery.

Adaptation Timelines Summary

System	Time to See Changes	Time to Optimize
Neuromuscular (coordination)	1-2 weeks	4-6 weeks
Lactate clearance	2-4 weeks	6-8 weeks
Aerobic enzymes	3-4 weeks	8-12 weeks
Mitochondrial density	4-6 weeks	12-16 weeks
Capillarization	6-8 weeks	16-24 weeks
Cardiac adaptations	8-12 weeks	24+ weeks
Bone/tendon strength	12-24 weeks	1-2 years

Implication: Base phases should be longer than athletes want. Intensity phases should be shorter. The deepest adaptations take months—there are no shortcuts.