16 weeks
Intermediate Half Ironman Program - 16 Weeks
Intermediate Half Ironman triathlon training plan: 16 weeks, 8 to 15 hours a week, building up to a 4h ride and a 2h run. 1.9 km swim, 90 km bike, 21.1 km run.
Intermediate Half Ironman plan at a glance
16 weeks · 8-15 h/week · 7-8 sessions
Long sessions with fuelling, race pace worked late in long sessions and long bricks. The plan starts from a 1.9 km swim, a 2h ride and a 1h run, and builds to 3 km, 4h 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 2h to 4h and the longest run from 1h 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 7, one bike-run brick a week, up to 2h30 + 40 min.
Intensity
2 quality sessions a week in the build phase; everything else is endurance (Z1-Z2).
Prerequisites and Required Level
To follow this intermediate Half Ironman plan from week one:
Swim 1.9 km without stopping
Ride 2h at endurance pace
Run 1h continuously
Have 8 to 15 hours a week available
Completed at least 1 triathlon
Mastered T1 and T2 transitions
Detailed Training Phases
16 weeks in four phases. Durations are those of the longest sessions at the start and end of each phase.
Base Phase
Weeks 1-6
Gradually extend endurance rides and runs
Objectives:
- Continuous swim: 1.9 km → 1.9 km
- Long ride: 2h → 2h35
- Longest run: 1h → 1h20
Key workouts:
- •1 technique or pace session(s) a week, the rest in Z2
- •Swim: 3 x 300 m at CSS + 3 s, 20 s rest
Build Phase
Weeks 7-11
Add tempo blocks inside the long sessions
Objectives:
- Continuous swim: 1.9 km → 2.5 km
- Long ride: 2h35 → 3h25
- Longest run: 1h20 → 1h40
Key workouts:
- •Swim : 6 x 300 m at CSS + 3 s, 20 s rest
- •Bike : 3 x 15 min in Z3, 5 min easy
- •Run : 3 x 8 min at half-marathon pace, 2 min jog
- •Brick : 1h45 + 30 min
Race-Specific Phase
Weeks 12-14
Race simulation: long session at race pace with the planned fuelling
Objectives:
- Continuous swim: 2.5 km → 3 km
- Long ride: 3h25 → 4h
- Longest run: 1h40 → 2h
Key workouts:
- •Swim : 4 x 500 m at race pace, 30 s rest
- •Bike : long ride with 3 x 20 min at race pace
- •Run : long run with 2 x 15 min at race pace
- •Brick : 2h30 + 40 min
Taper Phase
Weeks 15-16
Recover from peak volume without losing race pace
Objectives:
- Long ride cut to 2h
- Longest run: 1h
- Last hard session early in week 16
Key workouts:
- •Short reminders: long ride with 3 x 20 min at race pace at half volume
- •Open water swim if possible
Detailed Sample Week
Week 9 of 16, in the middle of the build phase: 7 to 8 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 intermediate version for a Half Ironman.
Swimming
Threshold (build)
1x/week6 x 300 m at CSS + 3 s, 20 s rest
Builds the continuous swim towards 3 km
Race pace (specific)
1x/week4 x 500 m at race pace, 30 s rest
Locks in race pace
Cycling
Long ride
1x/weekUp to 4h in Z2
Endurance and fuelling practice
Intensity
1x/week3 x 15 min in Z3, 5 min easy → long ride with 3 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/week3 x 8 min at half-marathon pace, 2 min jog → long run with 2 x 15 min at race pace
Race pace on tired legs
Brick
Bike then run
1x/week from week 72h30 + 40 min at peak
Gets the legs used to running off the bike
Races at this distance
To be ready on race day, start this 16-week plan on the date shown under each race.
IRONMAN 70.3 World Championship Marbella
Marbella, Espagne — 14 November 2026
Plan start: 25 July 2026
Ironman 70.3 Aix-en-Provence
Aix-en-Provence, France — 5 July 2026
Plan start: 15 March 2026
IRONMAN 70.3 Cannes
Cannes, France — 26 April 2026
Plan start: 4 January 2026
Ironman 70.3 Vichy
Vichy, France — 29 August 2026
Plan start: 9 May 2026
Triathlon de Gérardmer
Gérardmer, France — 14 June 2026
Plan start: 22 February 2026
IRONMAN 70.3 Oceanside
Oceanside, États-Unis — 4 April 2026
Plan start: 13 December 2025
IRONMAN 70.3 Les Sables d'Olonne
Les Sables-d'Olonne, France — 13 September 2026
Plan start: 24 May 2026
IRONMAN 70.3 Mallorca
Alcúdia, Espagne — 9 May 2026
Plan start: 17 January 2026
Technique in pictures
Nutrition for a Half Ironman
A Half Ironman takes 5h-6h 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 intermediate 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.
Doing every session at the same intensity
Solution: Easy sessions must stay easy so the quality sessions can be done well.
Frequently Asked Questions
This plan lasts 16 weeks: base in weeks 1-6, build in 7-11, race-specific work in 12-14 and taper in 15-16. It takes 8 to 15 hours a week over 7 to 8 sessions.
At the peak of the race-specific phase: a 3 km continuous swim, a 4h ride, a 2h run and a brick of 2h30 on the bike followed by 40 min of running.
In an average 12-hour week: about 1.5 h of swimming, 6 h of cycling and 4 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).
This plan adds 2 quality sessions a week in the build phase, for example 3 x 15 min in Z3, 5 min easy on the bike and 3 x 8 min at half-marathon pace, 2 min jog on the run. A time of 5h-6h is common at this level; most of the gain comes from doing those sessions consistently.
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.
Three landmarks: elbows bent (90–110°) to absorb shocks and relax the shoulders, knee still bent around 140–150° at the bottom of the pedal stroke (saddle height), stable back angle around 40–45°. Knee or neck pain is a fit problem: have it checked — ±5 mm of saddle height changes everything.
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