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Enduranceintermediate16 weeks

16-Week Marathon Prep

Run-focused training with cross-training days to build marathon endurance.

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About This Calendar

This 16-week marathon prep calendar takes a runner from a modest base — comfortable running 5-6K — to the start line of a full marathon. It uses three key sessions per week plus cross-training, which suits busy runners and those prone to overuse injuries: research shows most of the aerobic adaptation comes from the quality sessions, while extra junk mileage mostly adds injury risk.

The plan is built in classic phases. Weeks 1-4 build the aerobic base with easy runs and short tempo work. Weeks 5-7 develop endurance with 800m interval sessions and longer tempos, followed by a deload in week 8. Weeks 9-12 are marathon-specific: goal-pace runs stretching from 10K to 16K alongside long tempo runs up to 18K. Week 13 peaks with a 20K race simulation, and weeks 14-16 taper — volume drops sharply so you arrive at race day fresh, not detrained.

A realistic outcome for a first-timer following this plan is finishing strong, typically in the 4:00-5:00 range depending on your starting fitness; experienced runners can use the marathon-pace blocks to target a specific goal time. The taper matters as much as the buildup: trust the reduced volume in the final three weeks, because fitness is banked by then and rest is what converts it to performance.

Week-by-Week Overview

WeekFocusMondayWednesdayFriday
1Base BuildingEasy 5K RunCross-Train 30 minEasy 6K Run
2Base BuildingEasy 6K RunCross-Train 35 minEasy 7K Run
3Base BuildingEasy 7K RunTempo 4KEasy 8K Run
4Base BuildingEasy 8K RunTempo 5KEasy 9K Run
5EnduranceIntervals 6x800mEasy 8K RunTempo 7K
6EnduranceIntervals 8x800mEasy 9K RunTempo 8K
7EnduranceIntervals 10x800mEasy 10K RunTempo 9K
8DeloadEasy 6K RunCross-Train 30 minEasy 6K Run
9SpecificMarathon Pace 10KEasy 10K RunLong Tempo 12K
10SpecificMarathon Pace 12KEasy 10K RunLong Tempo 14K
11SpecificMarathon Pace 14KEasy 10K RunLong Tempo 16K
12SpecificMarathon Pace 16KEasy 10K RunLong Tempo 18K
13PeakRace Simulation 20KEasy 10K RunEasy 12K Run
14TaperEasy 10K RunTempo 6KEasy 8K Run
15TaperEasy 8K RunTempo 4KEasy 5K Run
16Race WeekEasy 4K ShakeoutRest / StridesRace Day Prep

How to Use This Calendar

  1. 1

    Anchor the three runs on non-consecutive days and treat the listed distances as targets, not minimums — easy runs should feel genuinely easy (conversational pace).

  2. 2

    Use the cross-training slots for low-impact aerobic work: cycling, swimming, or elliptical for the listed duration.

  3. 3

    Practice race-day fueling on every run over 90 minutes from week 9 onward — carbs, fluids, and the exact gels you plan to use in the race.

  4. 4

    Respect the taper. Do not add distance in weeks 14-16; the goal is to reach race morning feeling almost restless.

Frequently Asked Questions

Can I really train for a marathon on 3 runs per week?
Yes — three quality runs (intervals, tempo, and a long/marathon-pace run) plus cross-training covers the key adaptations while keeping impact volume low. Lower-mileage approaches like this are well established for injury-prone and time-limited runners. Runners chasing aggressive time goals may eventually want 4-5 runs weekly, but three is enough to finish strong.
What pace should my easy runs be?
Slow enough to hold a full conversation — typically 60-90 seconds per kilometer slower than your goal marathon pace. Easy running builds aerobic capacity with minimal fatigue; running these days too fast is the most common marathon-training mistake and undermines the quality sessions.
Why does the longest run top out at 20K instead of the full distance?
Because this plan measures long runs conservatively and relies on marathon-pace volume across weeks 9-13 for endurance. Runs beyond about 3 hours produce more damage than fitness for most amateurs. Race-day adrenaline, fueling, and the taper reliably carry trained runners from a 20K race simulation to 42.2K.
What should I eat during training runs and the race?
For runs over 90 minutes, practice taking 30-60 g of carbohydrate per hour (gels, chews, or sports drink) plus regular fluids. Rehearse your exact race-day fueling in the specific-phase long runs so your gut is trained — nothing new on race day.
What if I get injured or sick mid-plan?
Missing up to a week: resume where the plan left off. Missing two weeks: back up and repeat the last completed week. Missing three or more weeks: restart from an earlier phase and consider a later race. Never try to cram missed mileage into the remaining weeks — that is how one setback becomes two.

Pair It With

Core & Abs Workout

A short core routine for cross-training days — a stable trunk holds your running form together late in the race.

2-Day Full Body Program

Minimal-dose strength training that fits around run days and helps injury-proof your legs.

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