What it takes
The half marathon is where aerobic endurance becomes the primary limiter. Your plan needs a steady progression of long runs, race-pace tempo work, and enough easy volume to build mitochondrial density without breaking down. The best plans peak 10–14 days before race day and taper deliberately.
Training phases
| Weeks | Phase | Focus |
|---|---|---|
| 1–3 | Base | Aerobic foundation, easy volume, build long run to 8–9 miles |
| 4–7 | Build I | Tempo runs, threshold intervals, long run progression to 10–11 miles |
| 8–11 | Build II | Race-pace work, half marathon pace runs, long run to 12–13 miles |
| 12–13 | Peak | Highest quality week, race-simulation long run, sharpening |
| 14 | Taper | Volume reduced 40–50%, short race-pace touches, full recovery |
Key workouts
- Long runs building from 8 to 13 miles over the training cycle
- Half marathon pace runs: 4–8 miles at goal pace
- Tempo intervals at threshold (3 × 2 miles with 2-minute recovery)
- Easy recovery runs to maintain volume without adding stress
Am I ready?
You should be running 4–5 days per week with a long run of at least 6–7 miles. Ideally you've raced a 5K or 10K recently to establish pacing benchmarks. If you're coming from less than 15 miles per week, add 4–6 weeks of base building before starting a half marathon plan.
What to expect on race day
The half marathon is where fueling and pacing mistakes become expensive. Miles 1–6 should feel easy — genuinely easy. The middle miles (7–10) are where you settle into race rhythm. Miles 11–13 are where undertrained runners hit the wall as glycogen runs low. Practice taking gels or sports drink at miles 4–5 and 8–9 in training. Expect the last 5K to be the hardest running of the race.
Common mistakes
- Going out at goal pace from the gun — the first 2 miles should feel too slow; you'll make it up later
- Skipping the mid-race fuel — at 90+ minutes of racing, you need 30–60g of carbs per hour
- Running long runs too fast — long runs should be 60–90 seconds per mile slower than race pace
- Not practicing race-day logistics — shoes, nutrition, warmup routine should all be rehearsed before race day
- Too many runs at moderate effort — research on elite athletes shows ~80% of training volume should be genuinely easy, with quality concentrated in fewer hard sessions
Sample week
| Day | Session |
|---|---|
| Mon | RunEasy Run |
| Tue | RunTempo Intervals — 3×2mi |
| Wed | RunEasy Run |
| Thu | RunHM Pace Run |
| Fri | RestRest |
| Sat | RunLong Run |
| Sun | RunEasy Recovery |
How it works
The coach researches your race
Name your event and the coach searches the web for course profile, elevation, and conditions — then factors them into your half marathon plan.
Your plan starts where your fitness is
The coach checks your recent Strava activity and your local weather before recommending anything. A 12–16 weeks plan structured by phase — base, build, peak, taper — around what you can actually do.
Train, sync, adapt
Activities auto-match to planned sessions. The coach sees your paces, HR, and effort patterns — and adjusts as your fitness changes. Flag a bad week at work, a nagging knee, or a schedule change, and the plan adapts through conversation.
See it in action
Why AI coaching
- Long run progression paced to your aerobic development, not a fixed schedule
- Automatically adjusts when you need to move a long run or miss a week
- Taper length and intensity calibrated to your total training load
- Easy/hard balance grounded in the polarized training model — not guesswork
- Tell the coach about a bad night of sleep, a schedule change, or a nagging injury — and the plan adjusts through conversation, not a settings page
- Searches the web for your specific race — course details, elevation, and conditions inform the plan
Grounded in training science
Plan structure follows periodization principles from Daniels’ Running Formula and Pfitzinger’s Advanced Marathoning — base building, threshold development, race-specific sharpening, and taper. Intensity distribution follows the polarized model (Seiler 2010; Stöggl & Sperlich 2014) — roughly 80% of training at low intensity with targeted hard sessions, rather than moderate effort every day. Volume progression stays within evidence-based limits to manage injury risk (Nielsen et al. 2012). Taper protocols reflect findings from Wang et al. (2023), a meta-analysis of 14 studies on optimal taper duration and training load reduction for endurance events.
Seiler, S. (2010). “What is best practice for training intensity and duration distribution in endurance athletes?” Int J Sports Physiol Perform, 5(3). · Stöggl, T. & Sperlich, B. (2014). “Polarized training has greater impact on key endurance variables.” Front Physiol, 5. · Nielsen, R. et al. (2012). “A prospective study of overuse running injuries.” Br J Sports Med, 46(6). · Daniels, J. Daniels' Running Formula, 3rd ed. · Pfitzinger, P. & Douglas, S. Advanced Marathoning, 2nd ed. · Wang, Z. et al. (2023). “Effects of tapering on performance in endurance athletes: a systematic review and meta-analysis.” PLOS ONE, 18(5).
Frequently asked questions
- How long is a typical Half Marathon training plan?
- A well-structured Half Marathon plan typically runs 12–16 weeks, depending on your starting fitness level.
- How many hours per week for Half Marathon training?
- Most Half Marathon plans require 5–8 hours per week, scaling up through the build phase and tapering before race day.
- Can AI build a personalized training plan?
- Yes. An AI coach checks your recent training data, researches your specific race, and builds a periodized plan grounded in your actual fitness. Ask it why a workout is prescribed and it explains the reasoning. Flag an injury or schedule change and the plan adjusts through conversation — not a form field.