AI-built marathon training plan
16-24 weeks, 4-6 sessions/week. Long runs to 32-35 km, long tempo runs, race-pace simulations. EntrenAI requires base (12 months running + completed half marathon) and applies precise taper.
Updated
What is a marathon training plan?
The marathon (42.195 km) is the race where aerobic base is absolutely decisive. Typically run at 75-85 % VDOT (Marathon pace), below threshold but above Easy. The duration (2:30-5:00 hours for amateurs) makes metabolic endurance — the body's ability to oxidize fats + glycogen in efficient proportions — more important than aerobic power.
The plan is built on four pillars:
- High weekly aerobic volume (70-110 km/week for sub-3:30, 90-130 for sub-3, 110-160 for elite)
- Progressive long runs reaching 30-35 km
- Threshold tempo runs (40-50 min) and medium-long runs (10-15 km at marathon pace in build block)
- Strict safety prerequisites: 12 months prior base + half marathon completed in last 6 months + 25 km/week minimum sustained
Marathon is the popular race with the highest injury rate during prep: NYC Marathon studies report 48.5 % of runners with some injury during the plan. EntrenAI applies explicit restrictions to reduce that rate.
The paces you get, by goal
Every marathon goal has a VDOT (Daniels) and from it come the five paces the app writes every session with: easy (E), marathon pace (M), threshold (T), intervals (I) and repetitions (R). Find your goal in a column and you have the exact paces you will see in your plan.
| Marathon in 4:30 | Marathon in 4:00 | Marathon in 3:30 | Marathon in 3:00 | |
|---|---|---|---|---|
| VDOT | 32.8 | 37.9 | 44.6 | 53.5 |
| Easy (E) | 7:29 /km | 6:41 /km | 5:53 /km | 5:05 /km |
| Marathon pace (M) | 6:19 /km | 5:38 /km | 4:57 /km | 4:16 /km |
| Threshold (T) | 5:58 /km | 5:19 /km | 4:40 /km | 4:01 /km |
| Intervals (I) | 5:30 /km | 4:54 /km | 4:18 /km | 3:42 /km |
| Repetitions (R) | 5:06 /km | 4:33 /km | 3:59 /km | 3:26 /km |
| Equivalent to 5K · 10K | 28:30 · 59:13 | 25:14 · 52:22 | 22:00 · 45:37 | 18:48 · 38:59 |
Your AI-generated plan
1. Mandatory validation. Before starting, EntrenAI verifies:
- 12 months running regularly (minimum 25 km/week sustained)
- Half marathon completed in the last 6 months
- No active injuries in the last 4 weeks
- Age and cardiovascular health (medical clearance recommended for >40)
Don't meet the prerequisites? The plan recommends a half marathon season first (12-14 weeks) and re-evaluates after.
2. Target pace calculation. Your marathon pace is typically 18-25 seconds/km slower than half pace. For a runner with half at 1:35 (4:30/km), marathon ~5:00/km → 3:30:00. Daniels & Gilbert's calibrated formula calculates your VDOT and derives all paces automatically.
3. Typical weekly structure (5-6 sessions, intermediate):
- Easy 1: 10-12 km
- Quality 1: long cruise intervals or tempo
- Easy 2 + strides: 10 km
- Marathon-paced medium-long: 14-18 km with 8-10 km at marathon pace
- Easy 3 (if 6 sessions): 6-8 km recovery
- Long run: 24-35 km
4. Long run progression. Grows +2 km every 2 weeks until 30-35 km in build block. Max long run in specific block: 32-35 km (3.5-4.5 hours). Then long runs taper down progressively.
5. Marathon-specific sessions:
- Marathon-paced run: 14-20 km at target pace, key specific block session
- Long run with tempo finish: 26 km easy + 6 km at marathon pace
- Double session (advanced): 8 km easy morning + 12 km quality afternoon
6. 3-week taper. Longer than other distances due to accumulated fatigue. Volume drops -25 % wk1, -45 % wk2, -60 % wk3. Maintains 1-2 short quality sessions to avoid losing rhythm.
How the kilometres climb over the 18 weeks of the plan
From 50 to 88 km per week, with a deload every fourth week and 3 taper weeks. The thin bar is the long run, which reaches 32 km.
- Base
- Build
- Specific
- Taper
- Deload
- Long run
Who is this plan for?
- My first marathon (intermediate). You've run 1+ half marathon, solid base 35-45 km/week. 18-22 weeks, 5 sessions/week, 50-70 km/week in build block. Long runs to 28-30 km. Goal: comfortable finish, 4:00-5:00.
- PR my marathon (advanced intermediate). You've run 1-3 marathons, PR 3:30-4:30. 16-20 weeks, 5-6 sessions/week, 70-95 km/week. Long runs to 32 km + race-pace simulations. Typical improvement 10-25 min with specific prep.
- Sub-3:00 / sub-2:45 (advanced). Current PR <3:15. 16-18 weeks, 6 sessions/week (with 1-2 doubles), 90-130 km/week. Long runs 32-35 km with target-pace segments. Double quality session/week.
Never run more than 18 km? EntrenAI rejects the marathon plan and offers a half marathon plan first. Forcing marathon without base is the most direct recipe for serious injury.
How to run marathon in 3:30: the splits
The most expensive mistake in a race is going out fast. The plan teaches you the opposite: first 20% at 2% slower than goal pace, middle section on pace, last 20% slightly faster. This is what the watch reads at each point.
| Point | Segment pace | Elapsed time |
|---|---|---|
| km 5 | 5:04 /km | 25:21 |
| km 10 | 5:02 /km | 50:34 |
| km 15 | 4:58 /km | 1:15:25 |
| km 20 | 4:58 /km | 1:40:17 |
| km 25 | 4:58 /km | 2:05:09 |
| km 30 | 4:58 /km | 2:30:00 |
| km 35 | 4:57 /km | 2:54:46 |
| km 40 | 4:54 /km | 3:19:16 |
| Finish (42.2 km) | 4:54 /km | 3:30:01 |
Your first weeks, in detail
Week 11
Intermediate build — VDOT 50 (marathon target 3:25, pace 4:52/km)| Day | Session type | Detail | Duration |
|---|---|---|---|
| Monday | Easy | 12 km Z2 at 5:30/km. | 65 min |
| Tuesday | Long cruise intervals | 15 min warm-up + **4×3 km at 4:25/km (Threshold) with 90s jog** + 10 min cool-down. Total ~17 km. Key threshold session. | 85 min |
| Wednesday | Easy + strides | 10 km Z2 at 5:30/km + 6×100 m strides. | 55 min |
| Thursday | Marathon-paced medium long | 10 min warm-up + **14 km at 4:55/km (marathon target pace)** + 10 min cool-down. Total ~18 km. | 90 min |
| Friday | Recovery | 6 km Z1 at 6:00/km or full rest. | 0-35 min |
| Saturday | Easy | 8 km Z2 at 5:30/km. | 45 min |
| Sunday | Long run | 28 km Z2 at 5:30-5:45/km. Hydration every 25 min + 4-5 gels from km 8. No structure, focus on volume tolerance. | 165 min |
Week 16
Advanced specific — VDOT 60 (marathon target 2:50, pace 4:01/km)| Day | Session type | Detail | Duration |
|---|---|---|---|
| Monday | Easy + strides | 14 km Z2 at 4:30/km + 6×100 m strides. | 65 min |
| Tuesday | Long threshold tempo | 20 min warm-up + **2×20 min @ 3:50/km (Threshold) with 4 min jog** + 10 min cool-down. Total ~20 km. | 85 min |
| Wednesday | Easy double | Morning 8 km Z2 + afternoon 10 km Z2. Total 18 km at 4:35/km. Volume without concentrated fatigue. | 85 min total |
| Thursday | Extended marathon-paced | 10 min warm-up + **22 km at 4:01/km (marathon target pace)** + 10 min cool-down. Total ~26 km. Key specific block session. | 115 min |
| Friday | Recovery | 8 km Z1 at 5:00/km. | 40 min |
| Saturday | Easy with strides | 12 km Z2 at 4:30/km + 8×100 m strides. | 55 min |
| Sunday | Long run with tempo finish | 32 km at 4:30-4:45/km for first 24 km, last 8 km at 4:05/km (slightly slower than marathon pace). Hydration + 6 gels. Block accumulation peak. | 150 min |
These examples are real extracts from the EntrenAI planning engine. Your personal plan adjusts to your level, equipment and availability.
Equipment needed
EntrenAI automatically substitutes any exercise if you don’t have the gear.
- Training shoes + carbon-plated shoes ONLY for race day and specific simulations (>20 km)
- GPS watch with HR + 12+h battery (Garmin Forerunner 265+, COROS Apex 2 Pro)
- Chest HR strap + optional power sensor (Stryd) for power-based training
- Gel belt + handheld bottle + hydration vest for long runs >2h
- Gels (min 8-10 per long run >24 km), sports drinks + salt
- Foam roller + bands + percussion massager + chafing cream (Body Glide)
- Recommended: race-specific apparel tested in at least 2 prior long runs
What most people get wrong (and how to avoid it)
- 1
Skipping the prior base validation
Wanting to run a marathon without ever having run a 21K is the most direct recipe for serious injury or DNF. The half marathon is the critical predictor: not having completed a half in the last 6 months means you should NOT start a marathon plan. EntrenAI explicitly blocks. Injury rate without prior base is ~70 % vs ~30 % with proper base.
- 2
Long runs too long, too soon
Going to 30 km in week 6 of the plan is excessive if your base is 40 km/week. The 30 % rule applies here too: max long run is 30 % of weekly volume (with flexibility to 35 % occasionally in specific block). 28 km on a 70 km week is the safe max.
- 3
Not practicing race nutrition
First marathon with GI issues at km 25 you'll remember forever. Gels, salt, drinks must be tested exactly in at least 4-5 prior long runs. Golden rule: 60-90 g carbs/hour of running. More is hard to digest; less causes bonking.
- 4
Excessive race-day warm-up
In 5K/10K, 20 min warm-up is good. In marathon, 10-15 min is enough. Excessive warm-up + 42 km after = depleting glycogen before starting. Activation: 10 min easy jog + 4 short strides + 5 min hip mobility + 5 min in start corral moving calves.
- 5
Starting at target pace
In marathon, the first 10 km should go 5-10 seconds/km SLOWER than target pace. Adrenaline + pack + 'I feel good' = tactical error. Optimal strategy: first 10 km conservative, km 10-30 at target pace, km 30-42 if feeling great (rarely the case), match or slightly faster.
- 6
Skipping strength during the season
In marathon plans it's common to drop strength for 'lack of time'. Wrong. **2 strength sessions/week maintain muscle mass and prevent injury**, especially squat, Romanian deadlift, single-leg, and core. Without strength, running economy worsens 3-5 % and plantar fasciitis / Achilles tendinopathy are much more likely.
- 7
Ignoring the 'wall' zone
The 'wall' is hepatic and muscular glycogen depletion typically between km 30-35. Cause: too-fast pace in the first 25 km + insufficient nutrition. Prevention: controlled pacing + 60-90 g carbs/hour from the start + long simulations in training. EntrenAI codes 32 km simulations with tempo finish specifically to train this passage.
- 8
Running marathon with reduced half-plan
Adding long runs to a half marathon plan without reorganizing volume and intensity is NOT a marathon plan. Marathon-specific adaptation requires twice the volume and far less VO2max intensity — half plan has too many intervals and not enough sustained mileage. EntrenAI rejects adapted templates and builds a specific plan.
Other Running plan variants
Back to the general Running plan
- AI-built 5K training planA 5K plan tuned to your real VDOT, with track intervals, tempo runs and a long run over 3-5 sessions a week. From a first sub-30 5K to sub-18.
- AI-built 10K training planA 10K plan tuned to your real VDOT: long tempo runs, VO2max and threshold intervals and a weekly long run. From a sub-60 first 10K to sub-37.
- AI-built half marathon training planA half marathon plan calibrated to your real VDOT: progressive long runs up to 20 km, threshold tempo, VO2max intervals and a validated taper.
- AI-built beginner running planA beginner running plan that takes you from sedentary to a comfortable 5K in 10-14 weeks with a progressive run-walk method, 3 sessions a week.
- AI-built sub-50-minute 10K planA 12-week plan to run 10K in under 50 minutes at 4:50/km, built on threshold work, 1 km intervals and a progressive long run. For 55-60 minute 10K runners.
- AI-built sub-2-hour half marathon planA 14-16 week plan to run your half marathon under 2 hours at 5:41/km, with threshold work, tempo runs and an 18-22 km long run. For sub-55 10K runners.
- AI-built running plan for weight lossA running plan for weight loss that combines Z2 running, two strength sessions a week and a moderate calorie deficit over 12-16 weeks, injury-free.
Frequently asked questions
18-24 weeks minimum from a base of 35-45 km/week and a completed half. From total sedentary: 2-3 years (5K → 10K → half → marathon with adaptation time between each). Rushing the timeline is the direct recipe for injury and dropping out at km 30-35.
Approximations: marathon sub-5h → 26-30 km. marathon 4:00-4:30 → 28-32 km. marathon 3:30-4:00 → 30-33 km. marathon sub-3:30 → 32-35 km. The 30-35 % weekly volume rule is strict. Long runs >35 km produce damage no taper recovers.
1 gel every 25-30 min from km 6-8. For 3:00 race: 6-7 gels. For 4:00: 8-9 gels. For 5:00: 10-11 gels. Total: 60-90 g carbs/hour. Hydration: 500-700 ml/h with electrolytes (Na 500-700 mg/h in moderate climate, up to 1500 mg/h in heat).
Depends. Falling 5 km short on feel is not alarming — repeat next week or continue plan. Falling 10+ km short due to pain, severe fatigue or GI issues, review volume + recovery. If it happens 2 weeks in a row, EntrenAI recalibrates plan to a more conservative target time.
Recommended if chasing a PR (>3 % efficiency improvement, ~6-8 minutes on a 3:30 marathon). NOT necessary to finish. Carbon-plated shoes are reserved ONLY for race day and specific simulations (>20 km at target pace) — they last 400-500 km, don't waste them on quality training.
For amateurs: 1-2 marathons/year with specific prep for each (minimum 5-6 months between). For advanced: 2-3/year. More is counterproductive — the body needs 3-4 weeks recovery post-marathon before training hard again. Running 4-5 marathons/year = nearly guaranteed injury.
Pace and HR are dominant in marathon. Power (Stryd) is optional but useful for irregular terrain or changing conditions (heat). Elite runners combine all three. For amateurs, pace + HR is enough. EntrenAI auto-adjusts when power data is available.
Perfectly. Critical nutrients (protein, iron, B12, omega-3, creatine) can be covered with planning. Plant protein 2 g/kg (higher than omnivore due to lower digestibility), B12 supplementation mandatory, iron monitored every 6 months. Carbs are usually an advantage on plant-based diet.
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