How to stay injury free during marathon training

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Marathon training has a way of exposing every weakness in your body at exactly the wrong time. You’re three weeks out from race day, finally feeling fit — and then your knee starts talking to you on the stairs. Or your Achilles gets tight after a Tuesday tempo run and doesn’t loosen up by Thursday. Or you push through something that feels minor, and it becomes a month off.

This isn’t bad luck. Most marathon training injuries are predictable, and most of them are preventable — not by doing everything perfectly, but by understanding a few patterns and making smarter decisions before things go wrong. This article is built around that: practical, specific guidance for everyday runners training for 26.2 miles, not professionals with physios on speed dial and unlimited training time.

You don’t need to run fewer miles to stay healthy. You need to run smarter ones.

The 10% rule is a starting point, not a guarantee

You’ve probably heard it: don’t increase your weekly mileage by more than 10% from one week to the next. It’s decent advice as a rough guardrail, but it’s incomplete. A runner going from 20km to 22km a week is adding 2km. A runner going from 60km to 66km is adding 6km. The percentage is the same; the physical demand is very different.

What actually matters is your cumulative load over time. If you run 50km one week, 55km the next, and then throw in a hard parkrun on top of a long run because it’s a nice morning — your body is absorbing more stress than the numbers suggest. Intensity counts, not just distance.

A more useful framework: track both mileage and your hard sessions separately. In any given week, your long run plus any threshold or interval work should feel like the main events. Everything else should be genuinely easy — we’re talking 5:30–6:30/km for most recreational runners, where you can hold a conversation without gasping. If your “easy” runs are turning into moderate efforts, you’re accumulating fatigue you’re not accounting for.

Most injuries start as warnings — learn to read them

There’s a difference between the general tiredness and muscle soreness that comes with building mileage, and the kind of localised, specific pain that’s telling you something is wrong. The first is normal. The second is a message worth reading.

Pain that presents in one specific spot — the outside of your knee, the heel cord, the ball of your foot — and either worsens during a run, or is still there 24–48 hours after a run, is not something to run through in the hope it resolves. It rarely does. What starts as a niggle after a 25km long run has a tendency to become a proper injury after the 30km one three weeks later.

A useful rule: if something hurts, score it out of 10 during the run. A 1–3 that fades as you warm up and disappears completely within a day is probably manageable. A 4+ that doesn’t improve mid-run, or that lingers into the next day, means you back off, not push through. That might mean swapping a run for a 45-minute easy cycle, or doing 8km instead of 15km. It’s not failure. It’s sensible.

Structure your training week around recovery, not just mileage

One of the most common mistakes in marathon training isn’t running too much — it’s running too much on consecutive days without enough recovery between hard efforts. If you’re doing a tempo run on Wednesday and a long run on Sunday, that’s fine. If you’re doing a tempo run on Wednesday, a medium-long run on Friday, and a long run on Sunday, you’re not giving your body enough time to absorb the work.

Here’s a rough example of how a 5-day training week might be structured to balance load and recovery:

The point isn’t to follow this exact template — it’s to ensure you have at least one full rest day after your hardest session, and that your easy days are genuinely easy. If your legs are still heavy from Wednesday on Friday, the Friday run should be shorter or skipped entirely.

Strength work isn’t optional — but it doesn’t need to be complicated

Runners get injured in patterns. IT band syndrome, runner’s knee, shin splints, plantar fasciitis — the majority of these are linked to muscular imbalances, weakness in the hips and glutes, or poor load management. Running is a repetitive, single-leg sport. Every stride, your body is absorbing force through one leg at a time. If your glutes aren’t doing their job, your knees and feet have to compensate.

You don’t need to spend an hour in the gym three times a week. But two short sessions of 20–25 minutes of targeted strength work will make a real difference over a 16–20 week training block. Focus on:

• Single-leg work: Step-downs, single-leg Romanian deadlifts, split squats
• Hip strength: Clamshells, banded lateral walks, hip thrusts
• Calf strength: Single-leg calf raises, especially with a bent knee (works the soleus, which matters for Achilles health)
• Core: Not crunches — think dead bugs, planks, and single-leg bridges

Research from the British Journal of Sports Medicine consistently supports strength training as one of the most effective injury prevention tools for distance runners — more effective, in most cases, than stretching alone.

Shoes, surfaces and the stuff people overlook

Your shoes matter, but not in the way running stores sometimes imply. You don’t necessarily need the most cushioned shoe or the most “supportive” one — you need shoes that suit your foot shape and your running gait, and that aren’t worn out. A good rule: replace shoes every 600–800km. If you’re in a 16-week marathon training plan and running 50km/week, you’re putting around 800km on your shoes during that block alone.

Surface variation also helps. If all your running is on hard pavement, your legs are absorbing the same impact force thousands of times with no variation. Mixing in some trail or grass running — even 20–30% of your mileage — reduces repetitive stress. It also engages stabilising muscles you don’t use on flat roads.

And on the topic of easy-to-overlook factors: if you’re sleeping five or six hours a night, your recovery is compromised regardless of how well-structured your training is. According to NHS guidance, most adults need 7–9 hours for proper physical and cognitive recovery. You’re asking your body to absorb significant training stress on top of a regular working life. Sleep isn’t glamorous advice, but poor sleep is a genuine injury risk factor, particularly for stress fractures and soft tissue problems.

What to do when something goes wrong mid-training

Almost every marathon training block hits a bump. A week of illness, a flare-up of an old injury, a bad run that turns into three bad runs. The worst response is to panic and try to cram in missed sessions. The second worst response is to ignore it and push through.

If you miss a week of training — even two weeks — due to illness or minor injury in the first half of your training block, you can usually pick up close to where you left off and still have a successful race. In the final four weeks before marathon day, you’d be wise not to try to make up significant lost mileage; just get yourself to the start line healthy.

Some specific scenarios:

• Knee pain (runner’s knee or IT band): Reduce mileage by 30–40%, drop all downhill running temporarily, and add hip strengthening work. Don’t completely stop running unless advised by a physio — maintaining some load helps healing.
• Shin splints: Back off intensity immediately. Avoid back-to-back running days. Ice after runs. If it’s not improving within 7–10 days of reduced load, see a physio — stress fractures can present similarly.
• Tight Achilles: Never stretch an irritated Achilles aggressively. Reduce heel drop (avoid hills). Eccentric heel drops on a step are the best-evidence treatment once acute inflammation settles.

When to see a physio — and not to wait too long

There’s a version of this where you self-diagnose, try to manage an injury for six weeks, and end up with a worse problem. A good sports physio can usually tell you in one appointment whether something is serious, what you can and can’t keep doing, and what will actually help.

The barrier is usually time or cost. If it’s cost, consider this: one £50–70 physio appointment early in an injury is almost always cheaper than the entry fee you’ll lose if you have to DNS your marathon. If it’s time — most physios have evening or weekend appointments. It’s worth prioritising.

See someone promptly if: the pain is getting worse over several days of reduced training, there’s noticeable swelling or bruising, the pain woke you up at night, or you felt a distinct “pop” or “snap” during a run.

The honest takeaway

• Don’t just track mileage — track intensity. Two high-effort sessions a week is probably enough during marathon training. Everything else should genuinely be easy, not moderately hard.
• Pain that localises to one specific spot and doesn’t fade within 24–48 hours is a warning. Act on it early, not three weeks later when it’s become a real problem.
• Strength work twice a week for 20 minutes will do more for your injury resilience over a 16-week block than stretching ever will. Focus on glutes, hips, and single-leg calf strength.
• Shoes wear out. If you’re deep into a training block, check your mileage on your current pair. A worn-out shoe is a silent injury risk.
• Missing a week isn’t a disaster. Trying to cram it back in often is. Get to the start line healthy. A slightly undertrained runner who starts well will beat an injured one every time.