How often should you run during marathon training?

There’s no universal answer, of course. The number one rule of any exercise, especially the kind that turns toenails into distant memories, is that you have to adapt it to your own body. Some coaches swear by five runs a week, others say three is plenty, and there’s probably a PhD thesis somewhere proving that you can complete a marathon powered entirely by a positive attitude and isotonic drinks. Science can tell us a lot about VO₂ max and mitochondrial density, but it still can’t explain why your friend Steve can run 100k a week and never get injured while you pull a hamstring getting out of bed.

How much do I need to run during marathon training?

Most marathon plans include at least one 30k+ long run, with peak weekly mileage between 50–100k. At the lower end, you risk under-training and failing spectacularly come race day, at the higher end you risk over-training and injuring yourself and might not be able to race at all. To gauge what level you should aim for, consider how much you are training currently:

• If 50k/week feels fine: congrats, you’re among the freakish few who can handle volume without a meltdown.
• If 10–20k/week is your comfort zone: ideally you want to start increasing your weekly mileage well before you start marathon training so that running 30k every week is your baseline and feels comfortable. Stick to small increments and increase by no more than 10% per week, and don’t underestimate the beauty of a deload week.
• If you’re already strength training: you’re potentially better off starting marathon training than someone who has been running short distances for years but never lifted a barbell in their life. Yes, it will be an uphill battle with your cardiovascular system, but strong legs massively reduce your injury risk and you’ll be able to pound the pavement with much greater frequency than the average midlife crisis case who decides to run a marathon.

Marathon training is tough, you’re challenging your body physically, mentally and gastrointestinally - if you never run further than 10k then maybe don’t go for the Pfitzinger Marathon Plan. It is going to be hard enough anyway.

Why running frequency matters

Running more frequently isn’t just about endurance; it’s about adaptation. Each run trains your aerobic system (mitochondrial density, capillary growth) and musculoskeletal system (tendons, ligaments, bones). Repetition is what teaches your legs to keep moving when they, and probably you, are crying inside.

Too much running and you risk tipping into overtraining: your central nervous system starts to short-circuit. When that happens, your stride feels heavy, your coordination fades, your hormones misbehave, and you start crying at protein bar adverts.

Too little running, though, and you won’t have built the neuromuscular endurance to keep your form together over 42 kilometres. That’s when you see people staggering like newborn deer in the final miles, technically still running but powered purely by willpower and adrenaline. Yes, you can finish a marathon on adrenaline alone, but recovery will feel like you’ve been hit by a small bus for several days afterwards.

Avoiding injury when training for a marathon

Most marathon injuries don’t happen because people run too far—they happen because their muscles, tendons, and joints weren’t strong enough to handle the repetition. Every step when you run can load your body with up to three times your body weight. That force has to go somewhere, and if your muscles aren’t absorbing it, your joints and tendons take the hit. That’s how you end up with sore knees, tight hips, or the kind of Achilles pain that makes you wonder if your leg is trying to detach itself.

Strength training helps by making your connective tissue, the tendons and ligaments that hold everything together, denser and more resilient. It also improves eccentric control, which basically means your muscles get better at absorbing shock instead of letting your skeleton do it. Stronger muscles mean fewer stress injuries, faster recovery, and less chance of your form collapsing halfway through a long run.

Low-impact cross-training, like cycling, swimming, or reformer Pilates, keeps your aerobic engine running while sparing your joints from extra pounding. It lets you train your heart and lungs without adding another 20k of impact.

Cross training during marathon training

Running is the main course in marathon prep, but cross-training is the side dish that keeps you from burning out on carbs and cortisol. It means any activity that builds fitness without adding the same repetitive impact as running: cycling, swimming, pilates, yoga, rowing, or strength training.

Each type helps in a different way:

• Cycling strengthens your quads and glutes while keeping your heart rate in a similar zone to running. It trains endurance without wrecking your joints, and it’s perfect for recovery days when your legs have checked out.
• Swimming builds aerobic capacity while giving your body complete impact rest. It also improves breathing control - ideal if you’ve ever gasped through the second half of a race like a broken accordion.
• Strength training develops the muscle and tendon strength to handle the pounding of long runs. Heavy lifts like squats, lunges, and Romanian deadlifts make your legs more resilient and efficient.
• Pilates or yoga target the smaller stabilising muscles that keep your form together when fatigue hits. Reformer Pilates in particular is strength training disguised as a light stretch: it teaches control, balance, and humility (the shaking is mandatory).

Cross-training keeps your aerobic engine running while sparing your bones and connective tissue. It also helps even out muscular imbalances — the ones that lead to IT-band pain, hip drops, or that charming shuffle you develop in the final miles.

My own experience tracks perfectly with that logic. My half-marathon PB came after six months of heavy lifting and running only a few times a week — I was strong enough to maintain form and pace. But when I tried the same formula for a full marathon, my cardiovascular system couldn’t handle the accumulated fatigue. The takeaway: cross-training is brilliant support work, not a substitute for running.

Is 3 runs per week enough for marathon training?

It can be — but it depends entirely on what else you’re doing. Three runs per week can work if you’re adding 2–3 solid cross-training sessions (think cycling, swimming, or heavy lifting). The running builds your specific endurance; the other sessions keep your heart, lungs, and legs strong without the extra impact.

The problem isn’t fitness — it’s specificity. Running a marathon isn’t just about aerobic capacity; it’s about teaching your body to keep good form when everything hurts. That comes from cumulative fatigue — stringing several runs together each week so your muscles and nervous system learn to perform when tired.

When I trained for the NYC Marathon on only three runs a week, I felt amazing through training. My legs were fresh, my lungs were fine, and my ego was inflated. But come race day, I hit my longest training distance and my body decided it was done. My calves, quads, and inner thighs cramped in perfect unison — like a badly choreographed flash mob. That wasn’t dehydration or bad fuelling; it was neuromuscular fatigue — my brain literally couldn’t convince tired muscles to keep firing properly.

So yes, you can finish on three runs a week — but make sure you’re cross training enough to get that hideous cumulative fatigue.

Is 4 runs per week good for marathon training?

For most people, this is the sweet spot. Four runs a week gives you space for all the key ingredients of marathon fitness:

• A long run to build endurance.
• A tempo run to raise your lactate threshold (your ability to hold a tough pace).
• A speed or interval run to push your VO₂ max and improve efficiency.
• An easy run for active recovery and aerobic base building.

This mix teaches your body how to run long, fast, and tired — without pushing it to the point of collapse. It’s enough frequency to build strong connective tissue and efficient running mechanics, but not so much that you’re permanently wrecked.

For recreational runners with jobs, lives, and knees that occasionally hurt for no reason, this is the realistic balance between progress and preservation.

Is 5 runs per week good for marathon training?

Five runs per week is ambitious — and for some, perfect — but it comes with strings attached. You’ll make faster aerobic gains because you’re stressing your cardiovascular system more often, but you’ll also flirt with overtraining if recovery isn’t dialled in.

At this level, your body doesn’t just need sleep and carbs; it needs structure. You’ll have to rotate intensities carefully (no back-to-back hard sessions), keep strength work lighter, and actually take your easy runs easy.

Push too far, and your central nervous system starts rebelling. That’s when your legs feel heavy, you can’t hit paces you managed last week, and you start feeling inexplicably emotional at running shoe adverts. If you find yourself shivering or feverish without being ill, congratulations: you’re overcooked. Take a rest day before your body forces one on you.

Is 6 runs per week too much for marathon training?

Usually, yes. Running six days a week is a serious workload, and unless you’ve built up to it gradually over years, it’s a fast track to shin splints, burnout, and a long, meaningful stare into the void.

That level of frequency is typically reserved for runners whose bodies have already adapted to high mileage — the ones with efficient stride mechanics, bulletproof tendons, and no discernible social life. 

So… how often should you actually run?

How often you should run during marathon training depends on your experience, recovery, and tolerance for fatigue. Too few runs and your body never learns to run tired. Too many and you’re too tired to run at all. How often you run is a balancing act between progress and self-destruction — aim to suffer just enough to feel proud, not enough to need physio or psychotherapy.