Half Ironman (70.3) training plan
21 weeks, 6 sessions a week, up to 10.3 h of training a week at the peak. Here is the preparation structure Endu generates for an athlete at intermediate level targeting a Half Ironman. Your plan will be calibrated on your level, your available days and your feedback after every session.
Your plan for Half Ironman
A plan set to your level and free days, which adapts to your feedback after each session.
Your level?
14-day trial, cancel anytime.
Variations of this plan
- weeks
- 21
- sessions
- 125
- sessions / week
- 6
- peak week
- 10.3 h
Plan structure
Periodised in phases: build the base, move to race-specific work, then taper before the race.
- General preparationWeeks 1–2 · 2 wk
- BaseWeeks 3–8 · 6 wk
- BuildWeeks 9–13 · 5 wk
- SpecificWeeks 14–18 · 5 wk
- TaperWeeks 19–20 · 2 wk
- Race weekWeeks 21–21 · 1 wk
Volume progression
Week by week: lighter recovery weeks are built in to absorb the load.
| Wk | Phase | Hours | km |
|---|---|---|---|
| 1 | General preparation | 6.3 h | 21 |
| 2 | General preparation | 6.6 h | 22 |
| 3 | Baserecovery | 5.6 h | 19 |
| 4 | Base | 7.2 h | 23 |
| 5 | Base | 7.5 h | 24 |
| 6 | Base | 7.7 h | 25 |
| 7 | Baserecovery | 6.1 h | 20 |
| 8 | Base | 8.1 h | 25 |
| 9 | Build | 8.5 h | 28 |
| 10 | Build | 8.7 h | 28 |
| 11 | Buildrecovery | 6.7 h | 24 |
| 12 | Build | 9 h | 29 |
| 13 | Build | 9.2 h | 30 |
| 14 | Specific | 9.5 h | 30 |
| 15 | Specificrecovery | 7.2 h | 24 |
| 16 | Specific | 9.6 h | 30 |
| 17 | Specific | 10 h | 32 |
| 18 | Specific | 10.3 h | 33 |
| 19 | Taper | 7 h | 22 |
| 20 | Taper | 5.7 h | 18 |
| 21 | Race week | 3.6 h | 8 |
Sample week — week 12 (Build)
Real sessions from the plan with their targets. Each session is detailed step by step, and can be sent to a Garmin or COROS watch.
- MondaySwimmingEasy59 min continuous swim59 min · 2.7 km
- TuesdayRunningVery hard3 × 1.2 km at MAS2 min 30 s jog recovery48 min · 8.8 km
- ThursdayBrickHard1 h 30 bike + 17 min runincluding 3 × 10 min at threshold on the bike · run at marathon pace1 h 55
- FridaySwimmingHard10 × 200 m at threshold20 s recovery59 min · 2.8 km
- SaturdayCyclingEasy2 h 45 at endurance pace2 h 45
- SundayRunningEasyLong run 1 h 331 h 33 · 15 km
Example generated for a intermediate-level profile (MAS 15 km/h, 6 days available per week). Your plan will depend on your level, availability and feedback.
This plan’s check-up
Pass
A 21-week build (recommended minimum: 12); a longest run never more than 6% above the previous month’s; volume rising at most 13% from one week to the next; 82% of the time at easy effort; the longest session 3 weeks before the race; a taper cutting volume by 65% in race week.
2 worth knowing · 22 checks passed
Remarks
Strength training — No strength session.
Fueling — Long sessions (up to 195 min in this plan) are where race fueling is rehearsed.
The 22 checks passed, in detail
Length of the build — 21 weeks: enough for this race (recommended minimum: 12).
Sessions per week — 6 sessions a week: the minimum for this race is met.
Volume progression — Running volume rises at most 13% from one week to the next (a signal appears beyond 20%).
Long run increase — Each week, the longest run is at most 6% longer than the longest of the previous month (benchmark: 10%).
Lighter weeks — A lighter week comes back regularly (weeks 3, 7, 11, 15, 19).
Intensity distribution — About 82% of the time at easy effort: the most common distribution among trained endurance athletes.
Demanding sessions — No more than 3 demanding session(s) a week: suited to the level.
Hard days back to back — Demanding sessions are separated by easy days.
Rest days — At least one rest day a week.
Timing of the longest session — The longest session falls 3 weeks before the race: the right time.
Bike-run bricks — 10 bike-run bricks over the last 12 weeks.
Taper — Volume drops 65% in race week.
Intensity during the taper — Short race-pace efforts remain in the last two weeks.
Frequency during the taper — The number of sessions stays close to usual (92%).
Swim / bike / run balance — Swim 22%, bike 48%, run 30%: within coaches’ benchmarks.
Frequency per discipline — Each discipline comes back at least 2 times a week.
Sessions per week — 6 sessions a week: enough for a long format.
Open water — 5 open-water session(s) before the race.
Longest ride — The longest ride lasts 195 min (benchmark: 180 to 270 min).
Longest run — The longest run lasts 110 min (benchmark: 90 to 135 min).
Swim distance — The longest swim covers 174% of the race distance.
Long ride increase — The long ride grows in small steps.
Endu runs its own plans through the plan check open to everyone: same public rules, same thresholds, same sources. The rules and their sources, and a check of your own plan.
Why this plan works
Science-based periodisation
Base → build → specific → taper, with a recovery week every 3 to 4 weeks. Load goes up, but never two hard weeks in a row without a breather.
Paces, not vague feelings
Every session has target zones (pace, HR) computed from your MAS or a reference performance. A MAS test is built into the plan if you don't know yours.
Three disciplines, one load
Swim, bike and run are planned together: brick sessions, key sessions spread out, and a coherent total load week after week.
A plan that listens
After each session you rate how it felt (RPE). Too hard? The plan eases what follows. Skipped a session? It reschedules or absorbs it.
On your watch
On Garmin with the Endu app, on COROS by direct sync: the guided workout shows up on your wrist, step by step.
Reviews
What our users say.
4.8/5
Your plan, not a template athlete's
This plan is generated for an athlete at intermediate level with 6 days available per week. Yours will be calibrated on your MAS, your available days and your feedback after every session. 3 minutes. 14-day trial, cancel anytime.
Create my plan for Half Ironman14-day trial, cancel anytime.
Frequently asked questions
- Half Ironman: how many weeks of preparation?
- For an athlete at intermediate level, Endu builds a 21-week preparation. If your race is closer, the plan compresses phases while keeping the taper; if it's further away, it lengthens the preparation, and when the gap is large the preparation starts right away, gently and at your current volume, before building up.
- Is this plan well built?
- Pass at Endu’s plan check, the same as for any plan: 22 of 22 checks passed. A 21-week build (recommended minimum: 12); a longest run never more than 6% above the previous month’s; volume rising at most 13% from one week to the next; 82% of the time at easy effort; the longest session 3 weeks before the race; a taper cutting volume by 65% in race week. The rules and their sources are public on endu.fr/en/controle-technique.
- How many sessions per week?
- This example has 6 sessions per week. You choose 5 to 7 training days and the exact days (e.g. Tue, Thu, Sat, Sun): the plan sticks to them.
- I'm a beginner, is this plan for me?
- The plan adapts to your declared level (beginner to semi-pro): starting volume, progression and intensity change. Endu also offers a "Discovery" mode without a race to build a base first.
- Can I follow sessions on my watch?
- Yes, on Garmin and COROS. On Garmin, the Endu app (Connect IQ Store) shows today’s session and starts it as a guided workout. On COROS, link your account from your profile: your running, trail and cycling sessions land in the watch calendar. Other brands are not supported yet.
- How much does it cost?
- 14-day free trial, then €7.99/month with no commitment or €59.88/year (€4.99/month). Unlimited objectives and sports.