Marathon Long Run Progression How to Build It Safely

Your long run is the single most important session in marathon training, and also the easiest one to get wrong by pushing too hard, too soon. Build it by 1-2 miles a week — or roughly 10% of the long run's current distance, whichever is smaller — with a step-back week every 3-4 weeks, and keep the long run at around 25-35% of your total weekly mileage. Below: the table that matches your starting mileage, when to add a second long run, how to read the warning signs of pushing too fast, and where fueling and speed work fit around it.

Most runners don't get hurt by ignoring the 10% rule outright — they get hurt by applying the wrong table to their own starting point, or by holding a fixed schedule after their body already sent the signal to back off. That's the gap this page is built to close: not just the rule, but which version of it is actually yours.

Find Your Starting-Point Progression

The single biggest gap in most long run advice is that it assumes everyone starts from the same place. Someone running 15 miles a week needs a completely different build than someone already running 35. Here's the rough breakdown:

For the full week-by-week breakdown that matches your starting point, go to find your progression by starting weekly mileage. That page carries the actual detail — this one is here to route you to it.

One number I hold firm regardless of what the mileage table says: I never push an athlete's longest run past roughly 3 hours time-on-feet, whatever pace they're running. A pure mileage calculation doesn't know how long you'll actually be out there, and that's the number that matters for recovery.

Building Volume Without Breaking Down

Once your base progression is running smoothly, two structural questions tend to come up. First: should you add a second, mid-week long run? Done at the right point in a build, it extends your time-on-feet without piling everything into one punishing weekend session — see adding a second long run without overload. I've seen runners add this too early, before they'd held a stable 4-week base at their current peak, and their resting heart rate crept up before any soreness even showed. That's exactly the kind of signal the next link covers.

Second: how do you know if you're progressing too fast in the first place? Persistent soreness that doesn't clear, an elevated resting heart rate, or disrupted sleep are the three real red flags — full detail at warning signs you're progressing too fast.

Long Runs Aren't Just Mileage

Two things get treated as separate topics that really shouldn't be. The first is fueling. Rehearsing your race-day nutrition should be tied to specific long-run mileage milestones as your distance builds, not left until the final few weeks — see practicing race fueling at your long run milestones.

The second is pacing style. If you're running continuously, the tables above apply directly. If you're using run-walk intervals or training by time rather than distance — a valid and often smarter approach for first-timers, older runners, or anyone managing an injury history — you need a different governing structure. See progression for run-walk and time-based long runs.

The Speed-vs-Distance Question

As your long run grows, you'll eventually have to decide how much room is left for speed work in the same week. That balance is covered separately — see balancing long run growth with speed work for how to weigh the two against each other.

Back to the marathon training plan hub for everything else in your build.

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