How to Train for a Marathon: The Complete Guide
Preparing for a marathon takes 16 to 20 weeks of progressive training for most runners, built on four pillars: easy-pace running, one weekly long run, interval work and deliberate recovery. This guide sets out the full plan — weekly structure, nutrition, race strategy and the equipment that supports consistent training, including when a commercial-grade treadmill earns its place in your preparation.
How long do you need to train for a marathon?
- Beginner (first marathon): 20–24 weeks minimum, after comfortably completing a 10 km race.
- Intermediate (half-marathon finisher): 16–20 weeks.
- Experienced (chasing a time): 12–16 weeks of specific preparation on an existing aerobic base.
The four pillars of marathon training
- Easy-pace endurance running — 60–70% of weekly volume. Run at conversational pace. This builds the cardiovascular system and teaches the body to burn fat efficiently. It is the foundation everything else sits on.
- The weekly long run. Progressing from 1 h 30 up to 2 h 45–3 h at peak, it prepares muscles, tendons and mind for the 3 h 30–5 h most runners spend on the course.
- Intervals and threshold work. One session per week — e.g. 6 × 1,000 m at 10 km pace, or 2 × 20 min at threshold — raises your sustainable race pace.
- Active recovery. Easy cross-training (cycling, rowing, swimming), sleep and at least one full rest day per week. Adaptation happens during recovery, not during the session.
How many sessions per week — and how many kilometres?
| Profile | Sessions/week | Weekly volume | Longest run | Typical finish time |
|---|---|---|---|---|
| Beginner | 3–4 | 40–50 km | 28–30 km | 4 h 15–5 h |
| Intermediate | 4–5 | 50–70 km | 30–32 km | 3 h 30–4 h 15 |
| Advanced | 5–6 | 70–100 km | 32–35 km | Under 3 h 30 |
Increase weekly volume by no more than 10% per week, and cut volume by roughly a third every fourth week to absorb the training load.
Marathon nutrition: before, during, after
- The last 3 days: raise carbohydrate intake to 8–10 g per kg of bodyweight per day, keep fibre moderate, and hydrate consistently.
- Race morning: a familiar breakfast of 100–150 g of carbohydrate, finished 3 hours before the start.
- During the race: 30–60 g of carbohydrate per hour (gels or drinks tested in training), plus 400–600 ml of fluid per hour depending on heat.
- Afterwards: carbohydrate plus 20–30 g of protein within the first hour to start recovery.
The taper: your last three weeks
Reduce volume to 80% of peak three weeks out, 60% two weeks out and 40% in race week, while keeping a little intensity (short race-pace strides). A proper taper typically improves marathon performance by 2–3% — worth several minutes at no training cost.
Race strategy: avoiding the wall at kilometre 30
The “wall” is glycogen depletion, and it is avoidable. Start 5–10 seconds per kilometre slower than goal pace for the first 10 km, fuel from the first 45 minutes, and aim for even or slightly negative splits. Runners who go out 15 seconds per kilometre too fast typically lose 3–5 times that on the final 10 km.
Equipment that supports a marathon build
Beyond shoes (rotate two pairs, replace at 600–800 km), a treadmill removes the two biggest consistency killers — darkness and weather — and lets you run precise interval paces. For clubs, hotels and corporate gyms whose members train for endurance events, the machine must be commercial class: EN ISO 20957 class S, an AC motor of 3 hp or more and a running surface of at least 150 × 50 cm. Our commercial treadmill buying guide details the specification, and our treadmill incline guide explains how 1–3% incline replicates outdoor effort. Browse the full cardio equipment range for rowers and bikes used on cross-training days.
Frequently asked questions
What is a good time for a first marathon?
The global average finish time is around 4 h 20–4 h 30. For a first marathon, finishing comfortably matters more than the clock — most coaches suggest a conservative goal of 4 h 30–5 h for beginners coming from a half-marathon.
Should I run a half-marathon before a full marathon?
Yes — ideally 6–8 weeks before race day. It validates your pacing, fuelling and kit under race conditions, and doubles as a key long-effort session in the plan.
Can I run a marathon at 50 or older?
Absolutely. With medical clearance, age changes the recovery timeline more than the capability: plan longer between hard sessions (72 h rather than 48 h) and prioritise strength work twice a week to protect tendons and bone density.
How much treadmill running is acceptable in marathon training?
Up to 30–40% of weekly volume with no loss of race performance, provided long runs are mostly outdoors and the treadmill is set to 1–2% incline to match outdoor energy cost. Intervals in particular are often better paced on a treadmill.
Equip your facility for endurance training
Light In Fitness supplies commercial-grade treadmills, rowers and bikes to gyms, hotels, campsites and workplace fitness rooms across Europe — machines built for the volume that marathon training demands. Ask our team for a professional quotation within 24 working hours, including delivery, installation and maintenance options.
