Marathon training blocks: base, build, peak and taper

Marathon training blocks are the phases a good marathon plan moves through: base, build, peak and taper. Each block lasts a few weeks and has one main job. Base builds the engine. Build adds the marathon-specific work. Peak sharpens it. Taper clears the fatigue so you can use it.

A plan that's just "run more every week until race day" isn't a plan. It's a countdown. Below: how marathon training blocks work, how long each one should be, what goes in them, a sample 18-week layout, and where lifting fits if you also go to the gym. Build it yourself, or use a coach that adapts when life gets in the way when a week inevitably goes sideways.

Why marathon plans use training blocks

Training in blocks is periodization applied to the marathon. You don't train every quality at full effort every week. You stack them, in order, so each phase builds on the last and fatigue gets cleared on schedule instead of by injury. There's more on periodization in the hub post if you want the general theory.

For marathoners the blocks are longer and the volume higher than for shorter races, because the marathon is mostly an aerobic event and aerobic fitness takes time to build. The structure is the same one you'd use for anything else, including this hybrid training plan template if running isn't your only priority.

The idea of concentrating training on a few targets per phase comes from block periodization theory, which argues that "mixed" training aimed at many abilities at once produces conflicting responses, excessive fatigue and workloads too diluted to drive change (Issurin, 2010). Marathon plans are usually a gentler version of that: one main emphasis per block, with everything else maintained.

The four marathon training blocks

These lengths are coaching convention for a 16–20 week plan, not laws of physics. A shorter build squeezes the base. A longer one usually adds base, not peak.

Inside base and build, most plans step back every third or fourth week: less volume, same routine. That keeps the blocks from turning into a four-month grind.

Block 1: base

The job: run more, mostly easy, and get your legs used to time on feet.

Weekly volume climbs gradually and the long run gets longer. Nearly everything is conversational. Strides once or twice a week keep some leg speed. Strength training does its most useful work here, when running intensity is low and there's room for it.

The common mistake: skipping it because base is boring. The base decides how much hard work you can absorb later. Anyone who's wondered about a marathon with no training is really asking what happens when you skip this block entirely. Nothing good.

Block 2: build

The job: turn general fitness into marathon fitness.

Volume holds or keeps creeping up while intensity arrives: one threshold or tempo session a week, plus marathon-pace segments, often inside the long run. Some runners add short intervals or track workouts for marathon training here, but for the marathon they support the main work rather than replace it.

The long run is now the most important session of the week. Plan it as a hard day, and keep the days around it easy.

Block 3: peak

The job: rehearse the race.

This block holds your biggest weeks, your longest runs and your most specific sessions: long stretches at marathon pace, practicing race-day fueling, kit and breakfast. Volume is at its highest, so everything that isn't a key session stays genuinely easy.

It's also where fueling practice matters most. Long runs are where you learn what your stomach tolerates, and where healthy eating for marathon training stops being theory. For long events, up to 90 g of carbohydrate per hour may help in efforts beyond about 2.5 hours, with 30–60 g per hour a common target for shorter ones (Burke et al., 2011). Find your number in training, not on race day.

Block 4: taper

The job: arrive fresh.

Volume comes down across two to three weeks, a little marathon-pace work stays, and nothing new gets added. The research behind it: a meta-analysis found tapers of about two weeks with volume reduced by 41–60% and intensity and frequency kept were the most effective (Bosquet et al., 2007). In recreational marathoners, strict tapers of up to three weeks were associated with better finish times (Smyth & Lawlor, 2021).

The week-by-week version is in taper running marathon, and the general principles of cutting volume before race day apply to every race distance. If you're running a half as a tune-up race, how to taper for a half marathon is a shorter, lighter version of the same thing.

A sample 18-week marathon plan in blocks

For a runner training five days a week, lifting twice in the early blocks:

That's seven weeks of base, five of build (each block with a lighter week), three of peak and three of taper. Shift the numbers for your own calendar; keep the order.

Where lifting fits in marathon training blocks

If you run and lift, each block has to manage both, and running leads the whole way. Lifting supports it.

• ›Base: the best time to lift properly. Two sessions a week, moderate to heavy, while running intensity is low.
• ›Build: cut to one or two shorter sessions. Keep the main lifts, drop the volume. Never heavy legs the day before the long run or a quality session.
• ›Peak: maintenance. One short session, well away from the long run.
• ›Taper: last real lower-body session about 7–10 days before the race, then light upper body and mobility only.

Heavy lifting can go on a hard running day (run first, lift later) or on an easy day. What it can't do is sit right before the long run.

Marathon training blocks vs block periodization

Marathon blocks borrow from block periodization but are gentler. Classic block periodization concentrates heavily on one or two abilities per block and lets the others fade a little. A marathon plan keeps easy aerobic running in every block because aerobic fitness is the whole event. Our guide to block periodization covers the stricter version, which suits hybrid athletes alternating strength and running priorities across a year.

Common mistakes with marathon training blocks

• ›A short base. Jumping into marathon-pace work in week two because a plan template said so.
• ›No lighter weeks. Eighteen weeks of uninterrupted building is how marathon builds end in injury or illness.
• ›Every long run as a test. The long run builds durability. Most of it should be easy.
• ›Peaking too early. Your biggest weeks belong in the peak block, three to six weeks out, not in week nine.
• ›Cramming missed weeks. If illness takes a week, pick up where the plan is now. Don't try to make it up.

How exrsz builds marathon training blocks

exrsz builds a periodized marathon plan from your goal, race date, schedule, level and equipment, with base, build, peak and taper blocks and lighter weeks built in. It balances running and lifting in one plan, adapts each week to how you actually trained, and reshuffles missed sessions instead of cramming them into the next block.

FAQ

What are marathon training blocks?

They're the phases of a marathon plan, usually base, build, peak and taper. Each block lasts a few weeks and has one main job, from building aerobic volume to rehearsing race pace to clearing fatigue before race day.

How long should each marathon training block be?

For a 16–20 week plan, a common split is 6–8 weeks of base, 5–6 of build, 3–4 of peak and 2–3 of taper. Shorter plans squeeze the base; longer ones usually add base rather than peak.

How many weeks is a marathon taper?

Usually two to three weeks. In data from over 158,000 recreational marathoners, strict tapers of up to three weeks were associated with better finish times (Smyth & Lawlor, 2021).

Should I lift weights during marathon training?

Yes, with the dose changing by block: most in the base, maintenance through build and peak, and only light work in the taper. Keep heavy leg sessions away from the day before the long run or a quality session.

Can I skip the base block if I'm already fit?

You can shorten it if you're already running consistent volume. Skipping it entirely means starting marathon-specific work without the durability to absorb it.