Half marathon training plan, 10 weeks, on Garmin
Running Workout's half marathon plan runs 10 weeks, with 3 or 4 sessions per week, and progressively builds half marathon race pace up to a long run of about 19-20 km finishing at that pace. Every session is written by your AI coach and synced to your Garmin watch.
Last updated: 2026-09-19
A 10-week plan, four phases
The plan opens with a base phase (weeks 1 to 3) that builds volume and threshold, then a development phase (weeks 4 to 6) where threshold work extends and half marathon pace enters the picture.
Next comes the race-specific phase (weeks 7 to 9), with long runs finishing at half marathon pace, followed by a taper week to arrive fresh on race day.
| Phase | Weeks | Goal |
|---|---|---|
| Base | 1 to 3 | Build volume and threshold |
| Development | 4 to 6 | Threshold extends, half marathon pace enters |
| Race-specific | 7 to 9 | Long runs finishing at half marathon pace |
| Taper | 10 | Less volume, pace stays, then the race |
Sessions built around your own VMA, not an average
Each week combines two quality sessions, a long run and an easy run. As with the marathon plan, the balance shifts as it progresses: more VMA work early on, more half marathon pace as race day nears.
- VMA work, in repeats of 30 seconds to 3 minutes, to push back the aerobic ceiling.
- Threshold work, in 8-to-12-minute blocks, for the best return on sustained-intensity effort.
- Half marathon race pace, in repeats growing from 1 to 6 km, to get the body used to race rhythm.
- The long run, building up to about 19-20 km, with a half-marathon-pace finish from the race-specific phase onward.
These targets are never fixed: your AI coach converts them into a real pace automatically, from your VMA as measured or declared in the app.
The long run and race day
The long run climbs progressively to about 19-20 km, with a half-marathon-pace finish as soon as volume allows — the best way to teach your body to hold that pace late in the race.
On race day, the plan's template session covers the first two kilometres at target pace plus 5 seconds per km, then a steady rhythm — the last five kilometres, it's just about giving whatever is left in the legs.
How to start this half marathon plan
You pick your race date and weekly session count, 3 or 4, on the app's Plan screen. Your AI coach — Claude, ChatGPT or Gemini connected via MCP — then reviews these settings with you, and builds and pushes the sessions to your Garmin watch, week by week.
The plan stays editable at any time: date, variant or stopping it all happen from the same screen. The connection guide explains how to link your AI assistant the first time.
Frequently asked questions
How long is Running Workout's half marathon plan?
10 weeks, across four phases: base, development, race-specific and taper.
Does the plan adapt to my level and availability?
Yes: you choose 3 or 4 sessions a week, and target paces — threshold, VMA, half marathon pace — are calculated automatically from your VMA.
Are sessions sent automatically to my Garmin watch?
Yes. Once the plan is confirmed with your AI coach, sessions are built and pushed to your Garmin Connect calendar week by week.
Can I change or stop the plan partway through?
Yes, from the Plan screen: you can change the race date, the variant, or stop the plan — sessions already sent to Garmin stay in place.
Ready to prepare for your half marathon?
Pick your race date and weekly session count: your AI coach builds the plan and pushes it to your Garmin.
Start the half marathon plan