Half marathon training plan: adjustable, all levels
The half marathon (21.1 km) is the queen of road running: long enough to reward endurance work, short enough to stay accessible. This half marathon training plan, adjustable from 10 to 16 weeks based on your level, structures volume, threshold sessions and race-pace work to drop your time.
Easy run, nasal breathing the entire way.
6×800 m at VO2 pace, 200 m jog recovery. 20 min warm-up.
Squats, lunges, planks, calves. 4 sets, moderate load.
Progressive long run, finish the last 20 min in upper endurance.
How many weeks do you actually need?
Minimum durations recommended by distance and level. Above the minimum, your plan extends automatically with more lead time. Below, the risk of under-preparation and injury increases.
| Distance | Beginner | Intermediate | Advanced |
|---|---|---|---|
| 5K / Beginner | 8 wk | 6 wk | 6 wk |
| 10K | 10 wk | 8 wk | 6 wk |
| Half Marathon | 14 wk | 12 wk | 10 wk |
| Marathon | 20 wk | 16 wk | 12 wk |
Adjustable plan: duration adapts to your real lead time, your level and your weekly constraints.
Half marathon specifics
21.1 km is raced at an intensity just above aerobic threshold: not a short explosive effort, not pure marathon endurance. Most of the gain comes from threshold and race-pace work.
The long run builds up to 1h45 - 2h, including blocks at half-marathon pace. That's what makes the difference on race day: holding pace through the last 5 km, where the race is won mentally.
Sample week: half marathon plan
Key week in the specific phase of a half marathon plan, set here at 12 weeks (intermediate profile) around 4 to 5 weekly sessions.
Easy runs: 2
- · Tuesday : Easy run 45 min Z2
- · Thursday : Easy run 50 min Z2 + 6×100 m strides
Quality: 1 session
- · Wednesday : Threshold 3×10 min at half pace
Long run: 1×
- · Sunday : Long run 1h45 incl. 30 min at half pace
Volume and periodization: 12-week example (adjustable by level)
The example below is set at 12 weeks (intermediate). A beginner needs 14 weeks at lower volume; an advanced athlete compresses to 10 and runs more mileage. If you start earlier, TriCoach AI extends the base phase.
| Phase | Weeks | Weekly volume | Focus |
|---|---|---|---|
| Base | 1–4 | 30–40 km | Endurance, form, technique |
| Build | 5–8 | 40–55 km | Threshold, long intervals |
| Specific | 9–11 | 45–60 km | Half pace, long run with blocks |
| Taper | 12 | 25–30 km | Freshness, pace reminders |
5 common mistakes on a half marathon plan
- Running easy runs too fast: 80% of kilometers must stay in Z2, not the gray zone.
- Skipping race-pace work: without blocks at half pace in the long run, you don't know if you can hold it.
- Ramping volume too fast: +10% per week max, recovery week every 4 weeks.
- Skipping strength work: a weak core means a form that collapses at the end.
- Starting too fast on race day: the first 3 km should be run slightly under target pace.
Strength & mobility
Strength & mobility
On a half marathon plan, 1 to 2 weekly strength sessions (squats, lunges, core, calves) protect knees and hamstrings, especially in the specific phase. Hip and hamstring mobility stays weekly throughout the prep.
Why your half marathon plan must adapt week by week
10 to 16 weeks is 3 to 4 months. No PDF plan can anticipate a flu, a work trip or heavy legs. TriCoach AI adjusts your half marathon plan every week based on what you actually completed and your fatigue, without breaking progression.
Build my half marathon planGear & training conditions
TriCoach AI adapts every session to your gear and access, declared in your profile.
- 2 pairs of running shoes in rotation (road + training)
- One carbon-plated or reactive pair for race day and 2-3 specific sessions
- Track access or flat measured stretch for threshold sessions
- Treadmill for precise intervals and winter
Frequently asked questions
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