Overview

A full Ironman — 3.8km swim, 180km bike, 42.2km run — is a life event, not just a race. Finishing requires twenty weeks of consistent work, careful recovery, and a willingness to restructure your life around training. This plan assumes you've completed a Half Ironman and have a current 70.3 time under 7 hours (or equivalent endurance base). If you haven't, do the Half Ironman plan first.

The plan is designed around 12-15 hours of training per week peaking at 18-20 hours for the biggest weeks. If you can't commit that time over five months, this isn't the right plan for you yet — and that's fine. An Ironman will wait.

Golden Rule: Finishing an Ironman is about accumulated aerobic capacity and metabolic efficiency, not speed. The athletes who DNF are usually the ones who trained too hard too often; the ones who finish are the ones who showed up consistently at moderate intensity.

Prerequisites

Half Ironman finished in under 7 hours in the last 12 months
Ability to swim 2km continuous, bike 4 hours continuous, run 2 hours continuous — separately
No major injuries in the last 6 months
15+ hours per week available for training across the plan
A bike that's been race-fit recently and a coach or experienced friend who can assess your swim stroke

The 20-Week Block Structure

Phase	Weeks	Focus
Base	1-6	Aerobic volume, low intensity, mobility work
Build 1	7-11	Progressive volume, tempo intensity, first century ride
Build 2	12-16	Peak volume, race-pace specificity, long bricks
Taper	17-19	Reduce volume, maintain intensity, logistics prep
Race	20	Race week

Every fourth week is a recovery week: reduce volume 30-40%, keep one intensity session.

Weekly Volume Targets

Phase	Swim	Bike	Run	Total
Base	8-10 km	150-200 km	40-50 km	12-14 hours
Build 1	10-12 km	200-280 km	55-65 km	14-16 hours
Build 2	12-14 km	280-380 km	65-80 km	17-20 hours
Taper	6-8 km	120-180 km	30-40 km	8-10 hours

Numbers are indicative — adjust based on how your body responds. If you're accumulating fatigue faster than these suggest, back off 10-15%.

Session Structure

Swim — 3 sessions per week

Tuesday — Technique + Threshold 400m warm-up, 8-10 × 100m at CSS pace, 400m cool-down (~2km)
Thursday — Long aerobic 3-4km continuous at steady pace. Open water from Week 8 onwards.
Saturday — Pre-ride short swim 1.5-2km easy, tapering into Saturday long ride

Bike — 3 rides per week (main volume driver)

Tuesday — Intervals 90 min total with 4-6 × 6 min at threshold
Thursday — Medium steady 2 hours Z2 with a 30-60 min tempo block
Saturday — Long ride The defining session. Progresses:

Week	Long ride duration
4	2.5 hours
8	3.5 hours
12	4.5 hours
14	5.5 hours
16	6 hours (peak)
18	3.5 hours (taper)

All long rides Z2-Z3, progressively practising race-day fuelling.

Run — 3 sessions per week

Monday — Easy run 45-75 min Z2
Wednesday — Intervals 45-75 min with threshold or tempo intervals
Sunday — Long run Progresses:

Week	Long run duration
4	90 min
8	2 hours
12	2:30 hours
14	2:45 hours
16	3 hours (peak)
18	2 hours (taper)

Bricks — 1 per week

Saturday long rides end with a 15-45 min transition run at steady pace. Weeks 12+ include a dedicated race-specific brick (75km bike + 15km run) once every 3 weeks.

The Rhythm of a Training Week (Build 2 Phase)

Day	Session
Mon	45 min easy run + strength session (45 min)
Tue	2km threshold swim + 90 min bike intervals
Wed	75 min run with tempo intervals
Thu	3-4km long aerobic swim + 2h bike steady
Fri	Rest day or active recovery (walk, yoga)
Sat	Long brick — 5h bike + 30-45 min transition run
Sun	Long run — 2:30h easy, or race-distance swim morning + long run

Fuelling — The Ironman Variable

You will burn 8,000-10,000 calories on race day. You cannot eat your way through that — but you can reduce deficit enough to finish.

Training fuel

Pre-session: carb meal 2-3 hours before long sessions
During bike: 60-90g carbs per hour, with electrolytes
During run: 30-60g carbs per hour for runs over 90 min
Post-session: 1-1.5g protein per kg bodyweight + carbs to replenish

Race day fuel (to practice in training)

Before: 600-800 kcal 3 hours before (oats + banana + honey is a classic)
Pre-swim: 30g carb gel 15 min before start
Bike: 90g carbs per hour + electrolytes (Nutrition plan: gels, bars, bottles timed)
Run: 60g carbs per hour + water every aid station

Practice this exactly in Saturday long sessions. Nothing new on race day.

Strength & Injury Prevention

Two sessions per week, 30-45 min each. Focus:

Single-leg stability (split squats, step-ups)
Core (plank, dead bugs, Pallof press)
Glute activation (hip thrusts, clamshells)
Upper body rowing (pulled back posture counters bike hunch)

Don't add hypertrophy volume — you're already fatigued. The goal is injury resistance, not muscle gain.

Taper (Weeks 17-19)

This is where most first-time Ironman athletes panic. Volume drops dramatically. You'll feel like you're losing fitness. You're not — you're absorbing it.

Week	Volume cut	Intensity
17	-30%	One threshold session per sport
18	-50%	Light intensity only
19	-70%	Only short, easy sessions

Race Week (Week 20)

Monday-Tuesday: Short easy sessions. Final logistics checks. Pack race bag.

Wednesday: 30 min easy run + 30 min easy bike ride + 15 min easy swim. Feel-good sessions only. Travel to race venue.

Thursday: Race registration. Bike check-in. Short easy swim (20 min) in race-venue water. Early to bed.

Friday: Rest. Walk course if possible. Hydrate aggressively. Carb-load lunch.

Saturday: Rest fully. Dinner by 18:00. In bed by 21:00. Breakfast for Sunday prepared.

Sunday — Race Day:

Breakfast 3 hours before swim start (400-500 kcal, simple carbs)
Arrive 90 min before start
Warm-up swim 10 min if permitted
Final gel 15 min before swim start

Race Pacing

Swim. Conservative first 500m. Find feet to draft. Breathe bilaterally to stay calm. Target 75-85% effort.

Bike. The hardest discipline to pace. Ride 10% below what feels good for the first 60km. You will feel like you're soft-pedalling. Trust it. Riders who race the first 90km pay for it with 90km of shuffling on the run.

Run. First 10km: easy. Next 20km: steady. Final 12km: grind. This is the only way to avoid walking. Aim to run every aid station except the first and last — walk those while you fuel.

What Can Go Wrong (and Plans for Each)

Stomach upset. Reduce fuelling intensity. Switch to water-only for 20-30 min, then reintroduce.
Mechanical on bike. You're on your own for repairs — carry two spare tubes, CO2, basic tool kit. Practice tube change in training.
Cold water swim. Wetsuit mandatory if legal. Start at the back. Acclimate 60 sec before stroking hard.
Heat on run. Cool at every aid station — ice under hat, water over body, walk if HR spikes.

Common Mistakes

Under-fuelling long rides. A 5-hour ride at 20g carbs/hour is a training session for bonking. Practice race-day fuelling volume.
Skipping recovery weeks. Accumulated fatigue masks as "I need to train more." It's the opposite.
New kit on race day. Your race shorts, socks, shoes, bottles should all have 100+ training hours on them before race day.
Pacing the bike hard. The number one reason first-time Ironmen walk the marathon.

What's Next

After an Ironman, recovery takes 4-8 weeks — genuinely. Light activity only for 2-3 weeks. Reassess your relationship with the sport before committing to another season. Some athletes do multiple full-distance races per year; most are better served alternating middle- and long-distance events.

A well-executed first Ironman will hover around 12-14 hours. A well-executed fifth Ironman might be 10-11. The longest part of the journey is getting to the start line healthy — this plan's real job.

Full Ironman: 20-Week Training Plan🔒

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