TriCoo

Ironman 70.3 training

The half distance, also called Ironman 70.3: 1.9 km swim, 90 km bike and 21.1 km run. It is half a day of work: an age-grouper finishes in about five to seven hours. Endurance is what matters most here. You do not just ride 90 km, you then run a half marathon.

How many weeks to train

TriCoo usually plans 20 weeks for a half: 10 weeks of base, 8 weeks of build and 2 weeks of taper. If there is less time, the plan shrinks, but not below 12 weeks.

This is not a window for your very first race. TriCoo does not recommend a half as a first race. Do a sprint or an Olympic first.

How TriCoo builds the plan

The core of the preparation is the long sessions. The long ride grows from week to week in small steps, from the length you have already ridden. It never goes beyond the time you gave for that day. The long run grows the same way.

In the build phase the long ride becomes a brick: a run straight off the bike. For intermediate and experienced athletes a brick comes every load week of the build, for beginners every second one. One week in 4 is a recovery week, one in 3 for beginners.

Sample week

Sample week

Week 11 of preparation, build phase. Total 8 h 10 min.

  1. Mondayrest
  2. Tuesday
    • Swim, 45 min, easy
  3. Wednesday
    • Bike, 1 h 30 min, easy
  4. Thursday
    • Run, 1 h 5 min, easy
  5. Friday
    • Swim, 45 min, easy
  6. Saturday
    • Bike, 2 h 40 min, brick: bike with a tempo block
    • Run, 20 min, brick: straight into an easy run
  7. Sunday
    • Run, 1 h 5 min, long

A sample for the profile below, computed by TriCoo. Your plan will differ.

Who this week was computed for

A made-up athlete, 35 years old, intermediate, who swims, bikes and runs regularly. No strength training chosen. Thresholds are known: bike power, run pace and swim pace. One main race, a standard preparation window.

Time by day: Tue swim up to 75 min, Wed bike up to 90 min, Thu run up to 75 min, Fri swim up to 60 min, Sat bike and run up to 180 min, Sun run up to 120 min. Monday is a rest day. 10 h a week in total. This is a setting of the example, not a norm for the distance.

For four weeks before the preparation the athlete trained like this: Tue swim 60 min, Wed bike 75 min, Thu run 60 min, Fri swim 50 min, Sat bike 180 min, Sun run 90 min. Fitness at the start of preparation was 60. From there TriCoo computed week after week, and every week was done exactly as planned. There are no missed sessions, illness or bad days in the calculation.

Generator version: endurance-week-v26.

Saturday is the main day of this week. A long ride with a tempo block, and a run straight after it. On Sunday, an easy long run. Weekdays are shorter: a swim, a ride and an easy run.

Bricks

The brick run for a half starts at 20 minutes. The bike part is the long ride of that week, so there is no single number for it. More on the Brick workouts page.

Taper

The taper lasts 2 weeks: volume 60%, then 40% of normal. More on the Tapering page.

Pick a race

Half distance races are in the race calendar. If you have done a half, the next step is the full distance.

TriCoo builds a plan around your schedule and recalculates it after every session, missed day and bad day.

About TriCoo

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Author: TriCoo editorial team. Written with the help of AI. The methodology was checked by CODEX, an AI system, against the TriCoo methodology and code. No human coach or doctor reviewed this article.

Checked on 28 September 2026. The TriCoo methodology is described in the help center, sources are listed on the Sources page.