20 weeks
Advanced Half Ironman Program - 20 Weeks
Advanced Half Ironman triathlon training plan: 20 weeks, 12 to 18 hours a week, building up to a 4h30 ride and a 2h run. 1.9 km swim, 90 km bike, 21.1 km run.
Advanced Half Ironman plan at a glance
20 weeks · 12-18 h/week · 9-11 sessions
Long sessions with fuelling, race pace worked late in long sessions and long bricks. The plan starts from a 2.5 km swim, a 2h30 ride and a 1h15 run, and builds to 3.5 km, 4h30 and 2h.
How this Half Ironman plan is built
A half-marathon after a 90 km ride: pacing and fuelling decide how the race ends.
Long session progression
The long ride grows from 2h30 to 4h30 and the longest run from 1h15 to 2h, step by step.
Lighter weeks
One week in 4, volume drops by about a third to absorb the previous weeks of work.
Bricks
From week 8, one bike-run brick a week, up to 3h + 45 min.
Intensity
3 quality sessions a week in the build phase; everything else is endurance (Z1-Z2).
Prerequisites and Required Level
To follow this advanced Half Ironman plan from week one:
Swim 2.5 km without stopping
Ride 2h30 at endurance pace
Run 1h15 continuously
Have 12 to 18 hours a week available
Multiple triathlons completed
Recent physiological tests (FTP, vVO2max)
Detailed Training Phases
20 weeks in four phases. Durations are those of the longest sessions at the start and end of each phase.
Base Phase
Weeks 1-7
Gradually extend endurance rides and runs
Objectives:
- Continuous swim: 2.5 km → 2.5 km
- Long ride: 2h30 → 2h55
- Longest run: 1h15 → 1h20
Key workouts:
- •2 technique or pace session(s) a week, the rest in Z2
- •Swim: 4 x 300 m at CSS + 3 s, 20 s rest
Build Phase
Weeks 8-13
Add tempo blocks inside the long sessions
Objectives:
- Continuous swim: 2.5 km → 3 km
- Long ride: 2h55 → 3h50
- Longest run: 1h20 → 1h40
Key workouts:
- •Swim : 8 x 300 m at CSS + 3 s, 20 s rest
- •Bike : 4 x 15 min in Z3, 5 min easy
- •Run : 4 x 8 min at half-marathon pace, 2 min jog
- •Brick : 2h05 + 30 min
Race-Specific Phase
Weeks 14-18
Race simulation: long session at race pace with the planned fuelling
Objectives:
- Continuous swim: 3 km → 3.5 km
- Long ride: 3h50 → 4h30
- Longest run: 1h40 → 2h
Key workouts:
- •Swim : 5 x 500 m at race pace, 30 s rest
- •Bike : long ride with 4 x 20 min at race pace
- •Run : long run with 3 x 15 min at race pace
- •Brick : 3h + 45 min
Taper Phase
Weeks 19-20
Recover from peak volume without losing race pace
Objectives:
- Long ride cut to 2h30
- Longest run: 1h15
- Last hard session early in week 20
Key workouts:
- •Short reminders: long ride with 4 x 20 min at race pace at half volume
- •Open water swim if possible
Detailed Sample Week
Week 11 of 20, in the middle of the build phase: 9 to 11 sessions. Sessions can move to another day, but keep an easy day after the hardest one.
Training zones:
Key Program Workouts
The sessions not to miss, in their advanced version for a Half Ironman.
Swimming
Threshold (build)
1x/week8 x 300 m at CSS + 3 s, 20 s rest
Builds the continuous swim towards 3.5 km
Race pace (specific)
1x/week5 x 500 m at race pace, 30 s rest
Locks in race pace
Cycling
Long ride
1x/weekUp to 4h30 in Z2
Endurance and fuelling practice
Intensity
1x/week4 x 15 min in Z3, 5 min easy → long ride with 4 x 20 min at race pace
Hold race pace on the bike
Running
Long run
1x/weekUp to 2h in Z2
Running endurance
Quality
1x/week4 x 8 min at half-marathon pace, 2 min jog → long run with 3 x 15 min at race pace
Race pace on tired legs
Brick
Bike then run
1x/week from week 83h + 45 min at peak
Gets the legs used to running off the bike
Races at this distance
To be ready on race day, start this 20-week plan on the date shown under each race.
IRONMAN 70.3 Oceanside
Oceanside, États-Unis — 3 April 2027
Plan start: 14 November 2026
IRONMAN 70.3 Venice-Jesolo
Jesolo, Italie — 24 April 2027
Plan start: 5 December 2026
IRONMAN 70.3 Mallorca
Alcúdia, Espagne — 8 May 2027
Plan start: 19 December 2026
IRONMAN 70.3 Da Nang
Da Nang, Vietnam — 9 May 2027
Plan start: 20 December 2026
Ironman 70.3 Aix-en-Provence
Aix-en-Provence, France — 23 May 2027
Plan start: 3 January 2027
IRONMAN 70.3 Victoria
Victoria, Canada — 30 May 2027
Plan start: 10 January 2027
IRONMAN 70.3 Elsinore
Elseneur, Danemark — 27 June 2027
Plan start: 7 February 2027
IRONMAN 70.3 Oregon
Salem, États-Unis — 18 July 2027
Plan start: 28 February 2027
Technique in pictures
Nutrition for a Half Ironman
A Half Ironman takes under 5h at this level: needs change with the length of the effort.
Long sessions
Every long ride is a rehearsal: aim for 60 to 90 g of carbohydrate per hour and note what your stomach tolerates.
Race day
A 5 to 7 hour race: most of the fuelling happens on the bike, in small amounts every 15 to 20 minutes. Plan for salt in hot weather.
Run
On the half-marathon, alternate water and sports drink at aid stations and carry gels you have tested in training.
Equipment for a Half Ironman
Essentials first; the rest can wait for a second race.
Swim
Essential
- Wetsuit tried in open water
Optional
- ○Tinted goggles for sun
Bike
Essential
- A position you can hold for 3 hours and more
- Storage for your fuel
Optional
- ○Aero bars or a tri bike
- ○Power meter
Run
Essential
- Shoes you have already run 2 hours in
Optional
- ○Cap and sunglasses
Common Mistakes to Avoid
The most frequent mistakes on a Half Ironman at advanced level.
Riding the first 30 km too fast
Solution: Excitement makes you start hard. Set a target pace or power and stick to it.
Trying your fuelling for the first time on race day
Solution: Every long session is a chance to test quantities and products.
Adding intensity when fitness is good
Solution: Progress comes from consistency: keep the planned number of quality sessions.
Frequently Asked Questions
This plan lasts 20 weeks: base in weeks 1-7, build in 8-13, race-specific work in 14-18 and taper in 19-20. It takes 12 to 18 hours a week over 9 to 11 sessions.
At the peak of the race-specific phase: a 3.5 km continuous swim, a 4h30 ride, a 2h run and a brick of 3h on the bike followed by 45 min of running.
In an average 15-hour week: about 2.5 h of swimming, 7.5 h of cycling and 5.5 h of running. For a Half Ironman, cycling takes the biggest share because it is the longest leg of the race (1.9 km swim, 90 km bike, 21.1 km run).
3 quality sessions a week, never on consecutive days, and a lighter week every 4 weeks. In the race-specific phase, the key sessions become: long ride with 4 x 20 min at race pace and long run with 3 x 15 min at race pace.
Pick the plan up at the current week without making up lost sessions. The plan has a lighter week every 4 weeks: if you missed more than 10 days, repeat the last completed week before moving on.
As a guide: 6h-7h for a first Half Ironman, 5h-6h at intermediate level, under 5h for the fastest. A half-marathon after a 90 km ride: pacing and fuelling decide how the race ends.
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